Multiple-resonance thermally activated delayed fluorescent (MR-TADF) emitters have emerged as promising candidates for organic laser applications due to the potential for simultaneously achieving large oscillator strength and triplet utilization. In this study, we investigate the impact of peripheral tert-butyl (t-Bu)- and phenyl (Ph)-substituents on the typical 9-(phenylcarbazol-3-yl)-9H-carbazole-3-carbonitrile (CzBN) MR framework. Although these modifications preserve the frontier molecular orbital distribution with large oscillator strengths, they significantly influence excited-state dynamics and molecular aggregation even at low doping concentrations. Introducing Ph substituents extends the π-conjugation extension of CzBN, promoting closer molecular packing, detrimental molecular aggregation, and significantly broadening the excited-state absorption (ESA) band, which negatively impacts lasing performance. In contrast, CzBN-tBu, incorporating t-Bu groups as nonconjugated substituents, demonstrated reduced molecular aggregation and a distinct separation between the ESA band and stimulated emission region. Consequently, the optimal distributed feedback lasing performance is achieved by CzBN-tBu across various doping concentrations, resulting in the lowest lasing threshold of 3.4 µJ cm-2. These findings underscore the impact of inherent aggregation at low doping ratios on lasing activities, highlighting the crucial role of rational peripheral engineering in modulating molecular interactions and excited-state dynamics, offering design strategies for developing MR lasing molecules.

The performance of B3LYP, PBE0, and CAM-B3LYP functionals in the prediction of the two-photon transition strengths (for low-energy transitions) of 18 dipolar donor-acceptor systems containing a difluoroborate moiety was evaluated against results obtained using the resolution-of-identity implementation of the coupled-cluster CC2 model. The generalized few-state model approach, in which the two-photon transition strength is expressed in terms of electronic structure parameters, i.e., excitation energies, dipole moments, and transition dipole moments, was applied to gain deeper insight into the behavior of selected exchange-correlation functionals. The obtained results show that all three functionals provide two-photon transition strengths that differ significantly from the reference strengths, especially in the case of molecules exhibiting the highest 2PA strength.

This literature review aims to explore the application of ablative fractional laser in chronic wound healing, focusing on its clinical efficacy and mechanisms of action. Additionally, it summarizes the various lasers and parameters utilized by the authors in their studies. A comprehensive literature search was conducted for studies published between 2008 and 2025 in the Google Scholar, Web of Science, Medline, and PubMed databases, using the keywords: Fractional, Laser, Chronic Wounds, Ulcers, Healing. A substantial body of evidence suggests that carbon dioxide (CO₂) and erbium: yttrium aluminum garnet (Er: YAG) lasers can significantly accelerate the healing of chronic wounds. However, treatment protocols vary considerably across studies, particularly in terms of treatment frequency, power output, and energy density. This lack of standardization makes it challenging to compare outcomes directly and to determine optimal treatment parameters. The majority of studies conclude that CO₂ and Er: YAG laser therapies effectively promote the repair of chronic wounds. Proposed mechanisms include precise debridement, reduction of bacterial burden, improved local perfusion, enhanced transdermal drug delivery, and activation of key signaling pathways, such as Transforming growth factor-β/smad(TGF-β/Smad). Further research is needed to establish standardized treatment protocols and identify the most effective laser parameters for clinical use.

The use of atoms, molecules, and free electrons in quantum amplifiers has greatly advanced precision measurements, paving the way for the development of extremely-low-noise quantum devices such as masers and lasers. Here, we investigate the signal amplification of interacting spins and observe the amplification of magnetic fields using mixtures of interacting alkali-metal and noble gases. In contrast to noninteracting systems used as amplifiers, we demonstrate that interactions resulting from random atomic collisions give rise to two distinct amplification phenomena. These phenomena provide essential resources for enhancing quantum sensing capabilities. Our results show that magnetic fields can be amplified by at least two orders of magnitude, enhancing magnetic sensitivity to the femtotesla per root hertz level. Additionally, we report a counterpart phenomenon, deamplification, where the magnetic noise response is suppressed by at least one order of magnitude within certain frequency regimes. In this work alkali-metal and noble-gas spins are weakly coupled. We further explore how the performance of amplification changes with the interaction strength as the two spin gases gradually enter the strong-coupling regime, unveiling hitherto unexplored amplification effects that hold promise for enhancing precision measurements.

The near-infrared (NIR) sensitized generation of lophyl radicals (L·) by heptamethine cyanine led to initiation of radical photopolymerization of multifunctional acrylates when different hexa-arylbisimidazoles (HABIs) and N-phenylglycine (NPG) operated as coinitiator. The latter functioned as donor. For a deeper understanding, heptamethine cyanines were used following a photoinduced electron transfer (PET). HABI derivatives with electron-donating and -withdrawing substituents demonstrated that those with electron acceptors resulted in a higher photopolymerization efficiency of multifunctional acrylates. Tri-(propylene glycol) diacrylate (TPGDA) and tri-methylolpropane triacrylate (TMPTA) served as the monomers. Sensitizers (Sens) exposed with a high intense NIR-light source at 808 nm exhibiting a positive charge in the cyanine pattern significantly operate more efficiently for radical photopolymerization than a Sens without a positive charge. Differences in efficiency of PET can give an explanation for these differences. The heat generated by the cyanine's internal conversion from S1 to S0 additionally influenced the endothermic reaction between L· and NPG. These systems worked in practical applications for dry film photoresists (DFRs), reported here for the first time.

Laser cleaning is widely used industrially to remove surface contaminants with high precision. Conventional methods, however, lack real-time monitoring and feedback loops, often necessitating over-machining to ensure complete contaminant removal, which leads to inefficient energy use and potential substrate damage. In this work, we demonstrate a concept of selective laser cleaning via the application of femtosecond laser pulses and polystyrene microbeads with a diameter of 15 μm. These microbeads model challenging scenarios in high-precision optical work and delicate surface treatments across laboratory and production settings. To enable adaptive, real-time cleaning, we integrated a neural network that predicts the sample's appearance after each laser pulse into a feedback loop, tailoring the cleaning process to a bespoke target pattern. This method ensures precise contaminant removal with minimal energy use, making it highly promising for applications demanding strict material control, such as wafer cleaning, sensitive surface treatments, and heritage restoration. By combining machine learning with ultrafast laser technology, our approach significantly enhances the efficiency and precision of cleaning processes.

Background/Objectives: The development of pharmacotherapy, particularly in antiangiogenic drugs, has led to the emergence of MRONJ as a significant side effect. With the increasing incidence of cancer, the management of MRONJ poses a growing challenge for clinicians. The aim of the study is to evaluate the effectiveness of photobiomodulation (PBM) in treating patients with stage I, II, and III medication-related osteonecrosis of the jaw (MRONJ). Methods: A total of 31 patients were divided into two groups: Group 1 (n = 14 patients), with Stage 1 MRONJ; and Group 2 (n = 17 patients), with Stage II and III MRONJ. In total, 10 patients had osteoporosis and 21 underwent cancer treatment. The sole variable under investigation was the stage of MRONJ, as all patients underwent the same photobiomodulation (PBM) procedure. For treatment protocol, PBM with a diode laser was used (Lasotronix Smart M Pro, Piaseczno, Poland) with the following parameters: 100 mW; continuous wave; 635 nm; 4 J/cm2 for 20 s; irradiance for one point: 0.398 W/cm2; fluency for one point: 7.96 J/cm2, and for four points, which was one appointment: 31.83 J/cm2; and tip diameter 8 mm (three points from buccal surface, perpendicular for the lesion and one point on the floor of the mouth) during each session. The protocol assumed 10 sessions at 3 days intervals. Antibiotic therapy (amoxicillin with clavulanic acid 875 mg + 125 mg or clindamycin 600 mg every 12 h) was started 3 days before PBM and continued for 14 days. Antibiotics were taken for 14 days in total. Pain was measured with VAS scale. Follow-up was after 3 and 6 months. Results: Among the 14 patients in Group 1, none exhibited any clinical signs or symptoms of MRONJ during the 3 months follow-up, and complete cure was achieved. While PBM resolved inflammation and pain in stage II MRONJ, further surgical intervention was necessary to fully address the condition. Conclusions: PBM is an effective treatment for achieving complete recovery in patients with Stage 1 MRONJ. However, in Stages II and III MRONJ, PBM significantly alleviates symptoms but requires complementary surgical intervention to achieve full resolution. A beneficial aspect is the reduction in pain symptoms and the extent of surgical intervention.

Organic semiconductors exhibit unique semiconducting behaviour due to π-electron delocalization along their molecular chains, making them attractive for various optoelectronic applications. However, their low optical damage thresholds have limited their use in nonlinear optics, particularly in stimulated Raman scattering. Here we demonstrate a general method to significantly amplify molecular vibrations in organic semiconductors by utilizing spectrally tailored gain from stimulated emission, bypassing the necessity for traditional optical cavities. This method achieves Raman thresholds as low as ~10-50 μJ cm-2 or ~2-10 kW cm-2, outperforming current Raman lasers by four orders of magnitude. The resulting nonlinear Raman response leads to cascaded Raman emission characterized by pump-dependent emission efficiency, a nonlinearity factor of 3.8, a signal-to-noise ratio of 30.9 dB and a bandwidth of 110 nm. Our study opens exciting prospects for the development of compact, efficient Raman amplifiers and lasers, leveraging the unique properties of organic semiconductors for advanced photonic applications, including high-sensitivity spectroscopy and versatile frequency conversion technologies.

The almost-two-centuries history of spectrochemical analysis has generated a body of literature so vast that it has become nearly intractable for experts, much less for those wishing to enter the field. Authoritative, focused reviews help to address this problem but become so granular that the overall directions of the field are lost. This broader perspective can be provided partially by general overviews but then the thinking, experimental details, theoretical underpinnings, and instrumental innovations of the original work must be sacrificed. In the present compilation, this dilemma is overcome by assembling the most impactful publications in the area of analytical atomic spectrometry. Each entry was proposed by at least one current expert in the field and supported by a narrative that justifies its inclusion. The entries were then assembled into a coherent sequence and returned to contributors for a round-robin review. A total of 48 scientists participated in this endeavor, contributing a combined list of 1055 individual articles spanning 17 sub-disciplines of spectrochemical analysis into what the current community views as "key" publications. Of these cited articles, 60 received nominations from four or more scientists, establishing them as the most indispensable reading materials. The outcome of this collaborative effort is intended to serve as a valuable resource not only for current practitioners in atomic spectroscopy but also for present and future students who represent coming generations of analytical atomic spectroscopists.

Biological lasers, representing innovative miniaturized laser technology, hold immense potential in the fields of biological imaging, detection, sensing, and medical treatment. However, the reported gain media for biological lasers encounter several challenges complex preparation procedures, high cost, toxicity concerns, limited biocompatibility, and stability issues along with poor processability and tunability. These drawbacks have impeded the sustainable development of biological lasers. Carbon dots (CDs), as a novel solution-processable gain materials characterized by facile preparation, low cost, low toxicity, excellent biocompatibility, high stability, easy modification, and luminescence tuning capabilities along with outstanding luminescence performance. Consequently, they find extensive applications in diverse fields such as biology, sensing, photoelectricity, and lasers. Henceforth, they are particularly suitable for constructing biological lasers. This paper provides a comprehensive review on the classification and application of existing biological lasers while emphasizing the advantages of CDs compared to other gain media. Furthermore, it presents the latest progress made by utilizing CDs as gain media and forecasts both promising prospects and potential challenges for biological lasers based on CDs. This study aims to enhance understanding of CD lasers and foster advancements in the field of biological lasers.

To investigate and describe the clinical presentation and outcomes of a case series with possible retinal laser injury following recreational laser shows and assess their attributability to laser exposure.

Multi-center case series.

All consecutive eyes with reported laser exposure from recreational laser show and confirmed retinal injury presenting between May 2022 and April 2023.

Data were collected including demographics, details of laser exposure, prior ophthalmic or significant past medical history, clinical presentation including visual acuity, fundus photography, optical coherence tomography (OCT) or fundus fluorescein angiography (FFA) if available, treatment used, and follow-up and final outcomes in terms of visual acuity and complications, if any. Fundus photographs and OCT images were analyzed.

Demographics of the cohort, presenting and final visual acuity, morphology of retinal injury on fundus photographs and OCT images, complications if any, regression analysis to test connections to known events.

The study included a total of 51 eyes of 51 patients, all of whom reported exposure to recreational laser shows. The mean LogMAR visual acuity at presentation was 1183 (SD 0.50). All the eyes had premacular hemorrhage of mean size 1.90 disc diameters (SD 1.29), while a dot of retinal whitening ("white spot") was observed within the parafoveal area in 13 eyes (32.5%). Laser hyaloidotomy was performed in 54.9% of eyes, while 45.10% were managed conservatively. The majority of eyes [22, 78.57%] showed complete drainage immediately after hyaloidotomy, while partial drainage occurred in six eyes (21.43%). Only two eyes (4.26%) exhibited small residual hemorrhage at the end of the three-month period. Final mean LogMAR visual acuity was 0.123 (SD 0.20). Complications included RPE changes and epiretinal membrane formation. The incidence of cases correlated well with significant cultural events.

The presentation in all eyes was strongly suggestive of laser injury. Even though the outcomes were favorable, complications were not uncommon. We strongly recommend the immediate introduction of regulatory measures and establishment of a monitoring framework for laser shows in India. We propose referring to these injuries as "non-occupational laser exposure retinopathy".

In recent years, the rapid advancements in laser technology have garnered considerable interest as an efficient method for synthesizing electrocatalytic nanomaterials. This review delves into the progress made in laser-induced nanomaterials for electrocatalysis, providing a comprehensive overview of the synthesis strategies and catalytic mechanisms involved in defect engineering, morphology tuning, and heterostructure formation. The review highlights the various laser-induced synthesis techniques in producing nanomaterials with enhanced electrocatalytic properties. It discusses the underlying mechanisms through which laser irradiation can induce defects, modify morphology, and create heterostructures in nanomaterials, ultimately leading to improved catalytic performance. The comprehensive summary of these synthesis strategies and catalytic mechanisms provides valuable insights for researchers interested in utilizing laser technology for the fabrication of advanced electrocatalytic materials. Furthermore, this review identifies the existing challenges and outlines future directions within this booming research field. By addressing the current limitations and discussing potential avenues for exploration, the review provides important guidance for researchers looking to design and fabricate laser-induced nanomaterials with desirable properties for advanced electrocatalysis and beyond.

Lead-free Sn-based metal halide perovskites are low-cost, high-efficiency photoelectric materials with significant potential for micro/nanolasers, addressing the biological and environmental toxicity of lead. This study explores the lasing behavior of single-crystal CsSnBr3 microsquare plates (MSPs) synthesized via two-step high-temperature vapor-phase epitaxy with steady-state and time-resolved photoluminescence (PL and TRPL) spectroscopies. The lasing behavior, dominated by excitons from 193 to 313 K, shows a lasing threshold of 122.5 μJ/cm2 at room temperature, supported by an exciton binding energy of 63.67 meV and a near-unity power-law relationship (k ≈ 1) between PL intensity and pump fluence. The characteristic temperature of the lasing threshold indicates the notable thermal stability of CsSnBr3 MSPs. Moisture is identified as a significant factor causing lasing failure in Sn-based perovskite MSPs. High crystal quality is essential for achieving lasing in micro/nanostructures based on Sn-based perovskites. These findings highlight the potential of high-temperature vapor epitaxial growth for Sn-based perovskite micro/nanolasers, paving the way for environmentally and biologically friendly optoelectronic devices.

Three homoleptic spin-flip (SF) emitters, namely [Cr(Mebipzp)2]3+ (1), [Cr(IMebipzp)2]3+ (2) and [Cr(bip*)2]3+ (3), have been successfully synthesized and characterized. The weak distortion compared to a perfect octahedron imparts favourable structural properties to the three complexes, which display spin-flip (SF) luminescence at approximately 740 nm with quantum yields in the range of 9-11% for 1 and 2 in deaerated acetonitrile solutions at 25 °C. Time-resolved luminescence and transient UV-vis absorption experiments unveiled lifetimes for the lowest-lying 2MC (metal-centered) of 1.5 ms for 1 and 350 μs for 2. The incorporation of iodine atoms onto the ligand scaffold in 2 accelerates the 2MC → 4A2 relaxation process through simultaneous enhancements in the radiative and non-radiative rate constants. In agreement, the experimentally calculated absorption oscillator strength for the 2MC ← 4A2 transition amounts to 9.8 × 10-7 and 2.5 × 10-6 for 1 and 2, respectively. The 2.5 factor enhancement observed in the iodine derivative indicates a higher spin-flip transition probability, translating into higher values of radiative rate constant (k rad). Interestingly, in compound 3, the substitution of the distal methyl-pyrazole with indazole rings causes an important bathochromic shift of the SF emission energy to 12 000 cm-1 (830 nm). Likely, the extended π-system and the more covalent bond character induced by the indazole decrease the interelectronic repulsion further stabilizing the SF excited states. The recorded excited state lifetime of 111 μs in 3 remains among the longest for a molecular ruby emitting beyond 800 nm. These discoveries signify an underexplored avenue for modifying deactivation pathways and emission energy while retaining high quantum yields and long-lived excited states in molecular rubies.

Chirality, a pervasive phenomenon in nature, is widely studied across diverse fields including the origins of life, chemical catalysis, drug discovery, and physical optoelectronics. The investigations of natural chiral materials have been constrained by their intrinsically weak chiral effects. Recently, significant progress has been made in the fabrication and assembly of low-dimensional micro and nanoscale chiral materials and their architectures, leading to the discovery of novel optoelectronic phenomena such as circularly polarized light emission, spin and charge flip, advocating great potential for applications in quantum information, quantum computing, and biosensing. Despite these advancements, the fundamental mechanisms underlying the generation, propagation, and amplification of chirality in low-dimensional chiral materials and architectures remain largely unexplored. To tackle these challenges, we focus on employing ultrafast spectroscopy to investigate the dynamics of chirality evolution, with the aim of attaining a more profound understanding of the microscopic mechanisms governing chirality generation and amplification. This review thus provides a comprehensive overview of the chiral micro-/nano-materials, including two-dimensional transition metal dichalcogenides (TMDs), chiral halide perovskites, and chiral metasurfaces, with a particular emphasis on the physical mechanism. This review further explores the advancements made by ultrafast chiral spectroscopy research, thereby paving the way for innovative devices in chiral photonics and optoelectronics.

To analyze national trends in the prevalence of office-based laryngeal ablative procedures and compare those with traditional operative excisional procedures utilizing direct laryngoscopy.

For years 2013-2022, the US Medicare Part B claims database was searched for Current Procedural Terminology (CPT) codes 31572 (flexible laryngoscopy with laser ablation of lesion), 31540 (operative direct laryngoscopy with excision of lesion), 31541 (operative direct microlaryngoscopy with excision of lesion), and 31545 (operative direct microlaryngoscopy with excision of lesion and local tissue flap reconstruction). For each CPT code, the total number of charges billed to the Medicare database in each calendar year was recorded and annual trends were analyzed. Biopsy procedures were not included.

The annual number of office-based laser procedures (CPT 31572) remained relatively constant since the CPT code was introduced in 2017 (range: 18887-25241 procedures annually, trendline slope = +16, R2:0.02). Office-based laser procedures comprised a small portion of total laryngeal excisional procedures (range: 8.4%-12.1%). The total number of operative laryngeal excisions, billed by CPT 31540 and 31541, declined over the studied time frame (Trendline slope = -132, R2:0.93; Trendline slope = -950, R2: 0.93 respectively).

Office-based laser procedures comprise a small fraction of procedures to remove laryngeal lesions. The number of office-based laser procedures has been relatively stable over the last 5 years. This finding contrasts with the prevailing health care trend toward office-based procedures. Further research is needed to understand the decrease in operative laryngeal lesion excision procedures observed over the last 10 years.

4 Laryngoscope, 135:823-828, 2025.

From the theoretical foundations of laser and energy-based applications for the skin to the development of advanced medical devices, the field of dermatologic surgery has undergone transformative changes.

To review the scientific and clinical advancement of laser and energy-based therapies within dermatologic surgery.

A literature search was conducted to identify important scientific advancements and landmark studies on light, laser, and energy-based devices within the field of dermatologic surgery.

Since the introduction of selective photothermolysis principles in the 1980s, numerous laser and energy-based devices have been developed to effectively treat vascular lesions, target pigmentation, remove tattoos, rejuvenate the skin, and remove hair. Beyond aesthetic applications, photodynamic therapy was introduced to treat various neoplastic and inflammatory conditions. Lasers have also been employed to enhance transcutaneous drug delivery, and new lasers continue to emerge for treating common inflammatory conditions, such as acne. These innovations have contributed to a paradigm shift toward safe and effective, but less invasive, procedure-based treatment in addressing medical and aesthetic concerns in dermatology.

Dermatologists have consistently led the way in the continuous development and innovative application of laser and energy-based devices to effectively address a variety of skin conditions.

This paper presents RecNet, an innovative convolutional neural network designed for reconstructing cecond harmonic generation frequency-resolved optical gating (SHG-FROG) traces. Unlike conventional approaches, RecNet incorporates noiseless sample constraints through a domain knowledge embedded loss function, enhancing the network's robustness to noise and interpretability. The encoder-decoder architecture is intentionally selected to match the dimensions of the trace diagram with intermediate representations, facilitating the effective application of these constraints. Comparative studies show that RecNet surpasses classical algorithms like PCGPA and network models that do not incorporate domain knowledge constraints in reconstruction accuracy and convergence ratio. Experimental results further confirm the superiority of RecNet.

We introduce a novel, to the best of our knowledge, method to achieve a highly efficient nonreciprocal magnon laser within a spinning cavity optomagnonic system, which integrates a magnon mode and two optical modes. The rotation of the YIG sphere triggers the Barnett effect in the magnon mode and the Sagnac effect in the optical modes. The directional input of a pump light leads to opposite Sagnac-Fizeau frequency shifts in these modes. By adjusting the angular velocity, we can simultaneously control both the Barnett and Sagnac effects. Significantly, increasing the spin angular velocity enhances the system's nonreciprocity and magnon gain, yielding an isolation rate of 38.7 dB and a low-threshold magnon laser. This method presents a promising avenue for developing a nonreciprocal magnon laser, with implications for spintronics and the advancement of nonreciprocal optical devices.

To compare microleakage beneath ceramic and metal brackets prepared with either acid etching or laser conditioning.

An in vitro study.

Department of Orthodontics, Faculty of Dentistry, Suez Canal University, Ismailia, Egypt.

A total of 40 intact human premolars were selected and divided into four equal groups. The groups received the same adhesive-application procedures with different surface treatments and type of brackets: groups 1 (AM) and 3 (AC) underwent phosphoric acid etching; groups 2 (LM) and 4 (LC) underwent laser enamel conditioning using a Er,Cr:YSGG laser. Metal brackets were then bonded to the teeth in groups 1 (AM) and 2 (LM) and ceramic brackets in groups 3 (AC) and 4 (LC). Subsequently, they were placed in fuchsin dye solution. Each premolar was sectioned longitudinally in the occluso-gingival direction at right angles to the brackets. The dye penetration depth was calculated using a stereomicroscope. Microleakage was measured along the enamel-adhesive interface at each section's gingival and occlusal levels. For group comparisons, the Tukey test was utilised as a post hoc test to determine statistical significance between groups. The independent sample t-test was utilised for comparing both subgroups.

The results demonstrated significantly more microleakage under metal and ceramic brackets bonded to enamel prepared with laser conditioning than with acid etching at both the gingival and occlusal surfaces and in total. The AC group exhibited the lowest amount of microleakage, but the LC group demonstrated the highest amount of microleakage.

The ceramic bracket group treated with acid etching exhibited the lowest level of microleakage. Microleakage values on the gingival and occlusal surfaces were higher in both bracket types for the laser etched groups.

Diabetes mellitus remains a global challenge to public health as it results in non-healing chronic ulcers of the lower limb. These wounds are challenging to heal, and despite the different treatments available to improve healing, there is still a high rate of failure and relapse, often necessitating amputation. Chronic diabetic ulcers do not follow an orderly progression through the wound healing process and are associated with a persistent inflammatory state characterised by the accumulation of pro-inflammatory macrophages, cytokines and proteases. Photobiomodulation has been successfully utilised in diabetic wound healing and involves illuminating wounds at specific wavelengths using predominantly light-emitting diodes or lasers. Photobiomodulation induces wound healing through diminishing inflammation and oxidative stress, among others. Research into the application of photobiomodulation for wound healing is current and ongoing and has drawn the attention of many researchers in the healthcare sector. This review focuses on the inflammatory pathway in diabetic wound healing and the influence photobiomodulation has on this pathway using different wavelengths.

Vibrational spectroscopy can be said to have started with the seminal work of Coblentz in the 1900s, who recorded the first recognisable infrared spectra. Today, vibrational spectroscopy is ubiquitous and there are many ways to measure a vibrational spectrum. But this is usually only the first step, almost always there is a need to assign the resulting spectra: "what property of the system results in a feature at this energy"? How this question has been answered has changed over the last century, as our understanding of the fundamental physics of matter has evolved. In this Perspective, I will present my view of how the analysis of vibrational spectra has evolved over time. The article is divided into three sections: past, present and future. The "past" section consists of a very brief history of vibrational spectroscopy. The "present" is centered around ab initio studies, particularly with density functional theory (DFT) and I will describe how this has become almost routine. For the "future", I will extrapolate current trends and also speculate as to what might come next.

This narrative review comprehensively synthesizes laser technology's clinical applications, advantages, and limitations in modern dentistry. The review of 67 articles published between 2018 and 2023 highlights the latest advancements, including photobiomodulation (PBM) for enhanced tissue healing and inflammation control, alongside innovative uses in implantology, endodontics, and teeth whitening. The findings underscore the transformative potential of lasers in improving dental treatment precision and patient outcomes while addressing the barriers to their widespread adoption, such as costs and training needs. This review emphasizes the integration of laser technology into routine clinical practice and identifies pathways for future innovations in dentistry.

The thermodynamically controlled self-assembly of bis-bidentate quaterpyridine ligand, L = 2,2':5',5″:2″,2‴-quaterpyridine, with CrII and subsequent oxidation to CrIII yields the first photoluminescent tetrahedral [CrIII4L6]12+ molecular cage. Single-crystal X-ray diffraction reveals the presence of two homochiral cages (ΛΛΛΛ and ΔΔΔΔ) in the unit cell that crystallize as a racemic mixture. Additionally, a PF6 anion is observed inside the cavity, in line with isostructural cages built with NiII or FeII. Each corner of the polyhedron is occupied by weakly antiferromagnetically coupled {Cr(bipy)3}3+ (bipy = 2,2'-bipyridine) patterns, as revealed by magnetometry. Upon light excitation in the UV-vis region, spin-flip luminescence from the 2E/2T1 excited states with a maximum at 727 nm (13755 cm-1) was detected at room temperature. The measured excited state lifetime of 183 μs is longer than the 102 μs recorded for the mononuclear [Cr(bipy)3]3+ complex under anaerobic conditions, whereas the luminescence quantum yields are in the same order of magnitude and amount to 10-2 %. The photoluminescence brightness, B, calculated using the maxima of the absorption spectra for both species, goes from 14 M-1·cm-1 for the mononuclear compound to 90 M-1·cm-1 for the tetrahedral cage. This 6-fold improvement is observed across the entire excitation wavelength range, and it is due to the incorporation of four light-harvester units in the molecular cage.

The tenet of the study is to evaluate the efficacy of low-level laser therapy (LLLT) as an adjunct to surgical periodontal therapy [open flap debridement (OFD)] on clinical parameters, gingival crevicular fluid (GCF) alkaline phosphatase (ALP) levels in GCF and wound healing.

Thirty subjects afflicted with chronic periodontitis showing evidence of horizontal bone loss on the radiograph, pocket probing depth (PPD) between 4 and 7 mm, and ≥20 natural teeth present in the oral cavity were included in the study. In every patient, OFD+LLLT was done in one quadrant and OFD in another was performed. The clinical parameters were assessed at baseline, 3 and 6 months visits while the GCF sample was collected at baseline visit and 6 months recall. Wound healing indices were recorded 1-week post-op surgery for each group.

The results showed an evident improvement in all the clinical parameters [pocket probing depth, gingival index (GI), plaque index (PI), and CAL] from baseline-6 months values; however, no statistically significant difference was seen on the intergroup comparison. Wound healing was statistically significantly superior in the OFD + LLLT group in comparison to the OFD group, indicating a positive effect of lasers on healing. Gingival crevicular fluid ALP levels in the two groups decreased after 6 months and a statistically significant reduction in the laser group indicated an anti-inflammatory effect.

The results clearly indicated the efficacy of lasers in terms of acceleration of wound healing and control of inflammation.

Lasers as an adjunct to surgical periodontal therapy evidently have an anti-inflammatory effect (decrease in GCF ALP levels) as well as accelerate the wound healing process. How to cite this article: Gupta R, Arora SA, Gupta G, et al. Effect of Open Flap Debridement with and without LLLT in Patients with Periodontitis on Wound Healing, GCF ALP Levels, and Clinical Parameters. J Contemp Dent Pract 2024;25(12):1148-1155.

A century ago it was discovered that metabolic processes in living cells emit a spectrum of very low intensity radiation. This was based on observations that radiant energy from proliferating cells can amplify the rate of cell division in other nearby cellular life. Although metabolic radiation is now thoroughly documented in research on ultraweak photon emissions (UPE), the original finding that UPE can enhance mitogenesis remains controversial. This controversy is addressed by establishing a physical basis for phenomenological observations that biological UPE can amplify mitogenesis in living cells. Enhanced mitosis is rationalized as a resonance effect based on open quantum systems theory using Fano and Feshbach's methods. This application of quantum theory to biology has important consequences for understanding health, medicine, and principles of living matter.

Optical biometry has fundamentally transformed cataract surgery, and 2024 marked 25 years since the introduction of the first optical biometer. In the early 1980 s, Fercher and colleagues pioneered the optical noncontact eye length measurement, leading to the first interferometric A-scan of the eye. This innovation, patented and later developed by Zeiss, culminated in the release of the IOLMaster in 1999, enabling more accurate and reproducible eye diagnostics. Over the years, optical biometry has evolved into advanced swept-source optical coherence tomography devices, accompanied by numerous formulas for calculating intraocular lens power. Today, this technology is crucial not only for cataract surgeries, especially in eyes previously treated with refractive surgery, but also in advancing our understanding of diseases across fields like cardiology and oncology.

This paper explores the development of elastic LiDAR technology, focusing specifically on key components relevant to solid target scanning applications. By analyzing its fundamentals and working mechanisms, the advantages of elastic LiDAR for precise measurement and environmental sensing are demonstrated. This paper emphasizes innovative advances in emitters and scanning systems, and examines the impact of optical design on performance and cost. Various ranging methods are discussed. Practical application cases of elastic LiDAR are presented, and future trends and challenges are explored. The purpose of this paper is to provide a comprehensive perspective on the technical details of elastic LiDAR, the current state of application, and future directions. All instances of "LiDAR" in this paper specifically refer to elastic LiDAR.

Relationship between excited state dynamics and nonlinear optical (NLO) parameters is very unique. Herein, three different polyoxometalates (POMs) namely WD-POM (Wells-Dawson POM) based porphyrin hybrids WDPOM3PyP, Trans-2WDPOM2PyP, and 3WDPOMPyP (having one, two, and three WD-POM respectively), and their porphyrin precursors with (Trishydroxyl amino methane) namely Tris3PyP, Trans-2Tris2PyP, and 3TrisPyP respectively have been used for the study. Fluorescence decay and Z-scan studies by using nanosecond (ns) time span conveys the corresponding lifespan for each excited state, along with the NLO analysis respectively. The calculated lifetime data were found in the range of 3WDPOMPyP (τ1 = 5.65 ns), Trans-2WDPOM2PyP (τ1 = 2.21 ns), and WDPOM3PyP (τ1 = 1.96 ns). Third order NLO measurements represented that WDPOM3PyP showed better NLO response (χ3 = 2.26 × 10-10esu and β = 1.54 × 10-5 esu) as compared to Trans-2WDPOM2PyP (χ3 = 1.73 × 10-10 esu and β = 1.53 × 10-5 esu), and 3WDPOMPyP (χ3 = 1.55 × 10-10 esu and β = 0.65 × 10-5 esu) obtained at wavelength of 532 nm. Electrochemical studies have shown that the minor energy differences between the singlet and triplet excited states are responsible for intercrossing system (ISC) that helps in the transfer of electrons from porphyrin moiety to WD-POM. By absorbing a photon, the excited species were produced causing an initial charge transfer. This charge transfer state undergoes an electron transfer decaying to the lowest triplet state, and singlet state causing an increase in NLO. The obtained results indicated potential uses in photonic and all-optical switching devices.

A series of highly emissive inert and chiral CrIII complexes displaying positive and negative circularly polarized luminescence (CPL) within the near-infrared (NIR) region at room temperature have been prepared and characterized to decipher the effect of ligand substitution on the photophysical properties, more specifically on the chiroptical properties. The helical homoleptic [Cr(dqp-R)2]3+ (dqp = 2,6-di(quinolin-8-yl)pyridine; R = Ph, ≡-Ph, DMA, ≡-DMA (DMA = N,N-dimethylaniline)) and heteroleptic [Cr(dqp)(L)]3+ (L = 4-methoxy-2,6-di(quinolin-8-yl)pyridine (dqp-OMe) or L = N 2,N 6-dimethyl-N 2,N 6-di(pyridin-2-yl)pyridine-2,6-diamine (ddpd)) molecular rubies were synthesized as racemic mixtures and then resolved and isolated into their respective pure PP and MM enantiomeric forms by chiral stationary phase HPLC. The corresponding enantiomers show two opposite polarized emission bands within the 700-780 nm range corresponding to the characteristic metal-centered Cr(2E'→4A2) and Cr(2T1 '→4A2) transitions with large g lum ranging from 0.14 to 0.20 for the former transition. In summary, this study reports the rational use of different ligands on CrIII and their effect on the chiroptical properties of the complexes.

Laser beam welding is the most modern and promising process for the automatic or robotized welding of structures of the highest Execution Class, EXC3-4, which are made of a variety of weldable structural materials, mainly steel, titanium, and nickel alloys, but also a limited range of aluminum, magnesium, and copper alloys, reactive materials, and even thermoplastics. This paper presents a systematic review and analysis of the author's research results, research articles, industrial catalogs, technical notes, etc., regarding laser beam welding (LBW) and laser hybrid welding (LHW) processes. Examples of industrial applications of the melt-in-mode and keyhole-mode laser welding techniques for low-alloy and high-alloy steel joints are analyzed. The influence of basic LBW and LHW parameters on the quality of welded joints proves that the laser beam power, welding speed, and Gas Metal Arc (GMA) welding current firmly decide the quality of welded joints. A brief review of the artificial intelligence (AI)-supported online quality-monitoring systems for LBW and LHW processes indicates the decisive influence on the quality control of welded joints.

The layered van der Waals material CrCl3 exhibits very strongly bound ligand field excitons that control optoelectronic applications and are connected with magnetic ordering by virtue of their d-orbital origin. Time-resolved photoluminescence of these exciton populations at room temperature shows that their relaxation is dominated by exciton-exciton annihilation and that the spontaneous decay lifetime is very long. These observations allow the rough quantification of the exciton annihilation rate constant and contextualization in light of a recent theory of universal scaling behavior of the annihilation process.

Background: Diabetic retinopathy (DR), as a complication of diabetes mellitus (DM), remains a significant contributor to preventable vision impairment in the working-age population. Laser photocoagulation is essential in treating DR in conjunction with anti-vascular endothelial growth factor (VEGF) injection, steroids, and vitrectomy. This review summarizes the history of laser photocoagulation and highlights its current role and long-term effectiveness in real-world conditions. Methods: The National Clinical Trial (NCT), PubMed, Google Scholar, and China National Knowledge Infrastructure (CNKI) databases were searched utilizing combined or individual keywords, and a total of 121 articles were reviewed by the authors. Results: Several novel laser photocoagulation technologies, such as patterned scanning laser, subthreshold micropulse laser, navigated laser, multimodal imaging-guided laser, and retina rejuvenation therapy, substantially decrease the adverse effects and improve the accuracy and security of laser therapy. Numerous studies have demonstrated the outstanding clinical efficacy of combination therapies with pharmacologic treatments like anti-VEGF in treating DR and diabetic macular edema (DME). A 20-year follow-up retrospective study in our center preliminarily demonstrated the long-term effectiveness of conventional laser photocoagulation. Conclusions: More clinical trials are required to confirm the clinical effectiveness of novel laser technologies. Better treatment protocols for the combination therapy may be detailed. Anti-VEGF treatment has better effects, especially for DME and in a short period. But in real-world conditions, given the long-term effectiveness and economic advantages of conventional laser treatment, it should be prioritized over anti-VEGF injection in certain situations.

Organic lasers have attracted increasing attention owing to their superior characteristics such as lightweight, low-cost manufacturing, high mechanical flexibility, and high emission-wavelength tunability. Recent breakthroughs include electrically pumped organic laser diodes and an electrically driven organic laser, integrated with an organic light-emitting diode pumping. However, the availability of efficient deep blue organic laser chromophores remains limited. In this study, we develop two novel rigid oligophenylenes, end-capped with carbazole and phenylcarbazole groups, to demonstrate exceptional optical and amplified spontaneous emission (ASE) properties. These oligophenylenes are not only solution processable but also exhibit remarkably high solution photoluminescence quantum yields (PLQYs) of 90% and high radiative rates of 1.35 × 109 s-1 in the deep blue range. Our theoretical calculations confirm that the carbazole and phenylcarbazole end groups play a pivotal role in enhancing the optical transitions of the oligophenylene laser chromophores, thereby elevating their emission oscillator strengths. Remarkably, these materials demonstrate low solid-state ASE threshold values of 1.0 and 1.5 μJ/cm2 (at 431 and 418 nm, respectively). To the best of our knowledge, these ASE thresholds represent the lowest reported at these specific ASE wavelengths in the literature, regardless of whether they are solution-processed or thermally evaporated films. Furthermore, they exhibit excellent thermal and photostability, low triplet quantum yields, as well as negligible overlap of excited-state absorption within the ASE emission region, making them excellent candidates for a new class of deep blue materials for organic lasers. By integrating insights from theoretical calculations and experimental validation, our study provides a comprehensive understanding of the design principles behind these high-performing organic laser chromophores, paving the way for the development of advanced organic lasers with enhanced performance characteristics.

Defect centers in insulators play a critical role in creating important functionalities in materials: prototype qubits, single-photon sources, magnetic field probes, and pressure sensors. These functionalities are highly dependent on their midgap electronic structure and orbital/spin wave function contributions. However, in most cases, these fundamental properties remain unknown or speculative due to the defects being deeply embedded beneath the surface of highly resistive host crystals, thus impeding access through surface probes. Here, we directly inspected the atomic and electronic structures of defects in thin carbon-doped hexagonal boron nitride (hBN:C) by using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Such investigation adds direct information about the electronic midgap states to the well-established photoluminescence response (including single-photon emission) of intentionally created carbon defects in the most commonly investigated van der Waals insulator. Our joint atomic-scale experimental and theoretical investigations reveal two main categories of defects: (1) single-site defects manifesting as donor-like states with atomically resolved structures observable via STM and (2) multisite defect complexes exhibiting a ladder of empty and occupied midgap states characterized by distinct spatial geometries. Combining direct probing of midgap states through tunneling spectroscopy with the inspection of the optical response of insulators hosting specific defect structures holds promise for creating and enhancing functionalities realized with individual defects in the quantum limit. These findings underscore not only the versatility of hBN:C as a platform for quantum defect engineering but also its potential to drive advancements in atomic-scale optoelectronics.

Polycrystalline yttrium aluminum garnet (YAG) ceramic doped with neodymium (Nd), referred to as Nd:YAG, is widely used in solid-state lasers. However, conventional powder metallurgy methods suffer from expenses, time consumption, and limitations in customizing structures. This study introduces a novel approach for creating Nd:YAG ceramics with 3D free-form structures from micron (∼70 µm) to centimeter scales. Firstly, sol-gel synthesis is employed to form photocurable colloidal solutions. Subsequently, by utilizing a home-built micro-continuous liquid interface printing process, precursors are printed into 3D poly(acrylic acid) hydrogels containing yttrium, aluminum, and neodymium hydroxides, with a resolution of 5.8 µm pixel-1 at a speed of 10 µm s-1. After the hydrogels undergo thermal dehydration, debinding, and sintering, polycrystalline Nd:YAG ceramics featuring distinguishable grains are successfully produced. By optimizing the concentrations of the sintering aids (tetraethyl orthosilicate) and neodymium trichloride (NdCl3), the resultant samples exhibit satisfactory photoluminescence, emitting light concentrated at 1064 nm when stimulated by a 532 nm laser. Additionally, Nd:YAG ceramics with various 3D geometries (e.g., cone, spiral, and angled pillar) are printed and characterized, which demonstrates the potential for applications, such as laser and amplifier fibers, couplers, and splitters in optical circuits, as well as gain metamaterials or metasurfaces.

We celebrate 80 years of EPR with a special issue of Applied Magnetic Resonance featuring both reviews and regular research articles. The focus is new opportunities for application of EPR and new directions for development of EPR. This introduction concisely surveys the scope of EPR and hints at future developments.

The field of molecular scattering is reviewed as it pertains to gas-gas as well as gas-surface chemical reaction dynamics. We emphasize the importance of collaboration of experiment and theory, from which new directions of research are being pursued on increasingly complex problems. We review both experimental and theoretical advances that provide the modern toolbox available to molecular-scattering studies. We distinguish between two classes of work. The first involves simple systems and uses experiment to validate theory so that from the validated theory, one may learn far more than could ever be measured in the laboratory. The second class involves problems of great complexity that would be difficult or impossible to understand without a partnership of experiment and theory. Key topics covered in this review include crossed-beams reactive scattering and scattering at extremely low energies, where quantum effects dominate. They also include scattering from surfaces, reactive scattering and kinetics at surfaces, and scattering work done at liquid surfaces. The review closes with thoughts on future promising directions of research.

Compressing the optical field to the atomic scale opens up possibilities for directly observing individual molecules, offering innovative imaging and research tools for both physical and life sciences. However, the diffraction limit imposes a fundamental constraint on how much the optical field can be compressed, based on the achievable photon momentum1,2. In contrast to dielectric structures, plasmonics offer superior field confinement by coupling the light field with the oscillations of free electrons in metals3-6. Nevertheless, plasmonics suffer from inherent ohmic loss, leading to heat generation, increased power consumption and limitations on the coherence time of plasmonic devices7,8. Here we propose and demonstrate singular dielectric nanolasers showing a mode volume that breaks the optical diffraction limit. Derived from Maxwell's equations, we discover that the electric-field singularity sustained in a dielectric bowtie nanoantenna originates from divergence of momentum. The singular dielectric nanolaser is constructed by integrating a dielectric bowtie nanoantenna into the centre of a twisted lattice nanocavity. The synergistic integration surpasses the diffraction limit, enabling the singular dielectric nanolaser to achieve an ultrasmall mode volume of about 0.0005 λ3 (λ, free-space wavelength), along with an exceptionally small feature size at the 1-nanometre scale. To fabricate the required dielectric bowtie nanoantenna with a single-nanometre gap, we develop a two-step process involving etching and atomic deposition. Our research showcases the ability to achieve atomic-scale field localization in laser devices, paving the way for ultra-precise measurements, super-resolution imaging, ultra-efficient computing and communication, and the exploration of light-matter interactions within the realm of extreme optical field localization.

Advancements in optical coherence control1-5 have unlocked many cutting-edge applications, including long-haul communication, light detection and ranging (LiDAR) and optical coherence tomography6-8. Prevailing wisdom suggests that using more coherent light sources leads to enhanced system performance and device functionalities9-11. Our study introduces a photonic convolutional processing system that takes advantage of partially coherent light to boost computing parallelism without substantially sacrificing accuracy, potentially enabling larger-size photonic tensor cores. The reduction of the degree of coherence optimizes bandwidth use in the photonic convolutional processing system. This breakthrough challenges the traditional belief that coherence is essential or even advantageous in integrated photonic accelerators, thereby enabling the use of light sources with less rigorous feedback control and thermal-management requirements for high-throughput photonic computing. Here we demonstrate such a system in two photonic platforms for computing applications: a photonic tensor core using phase-change-material photonic memories that delivers parallel convolution operations to classify the gaits of ten patients with Parkinson's disease with 92.2% accuracy (92.7% theoretically) and a silicon photonic tensor core with embedded electro-absorption modulators (EAMs) to facilitate 0.108 tera operations per second (TOPS) convolutional processing for classifying the Modified National Institute of Standards and Technology (MNIST) handwritten digits dataset with 92.4% accuracy (95.0% theoretically).

Spatial self-phase modulation based on the optical Kerr effect has gained momentum in recent years to analyse the nonlinear optical properties of 2D inorganic nanomaterials. In the present work, we investigate the strong light-matter interaction of organic semiconducting materials based on SSPM, by developing Cu-phthalocyanine (CuPc) nanotubes via a solvothermal technique. The low bandgap of CuPc facilitates the study of its nonlinear optical properties for a broad spectrum range from 671 nm to 405 nm. Intense laser light passing through the CuPc dispersion produces concentric diffraction ring patterns at the far field from which high n2 and χ(3) values, 3.667 × 10-5 cm2 W-1 and 2 × 10-3 esu, respectively, are obtained for the 405 nm laser. This strong nonlinear optical response of CuPc has been utilized to realize non-reciprocal light propagation by constructing a CuPc/SnS2 hybrid structure, which makes an effective all-optical photonic diode. In addition, the all-optical switching is presented using CuPc nanotubes based on the spatial cross-phase modulation technique. In this technique a phase change is induced in the weak signal beam modulated by the strong controlling light beam, which helps to produce all-optical logic gates and all-optical switching devices. The experimental findings of this work unravel the potentially powerful applications of CuPc nanotubes in all-optical information transmission and all-optical photonic devices.

Coherence measures the similarity of progression of phases between oscillations or waves. When applied to multi-scale, nonstationary dynamics with time-varying amplitudes and frequencies, high values of coherence provide a useful indication of interactions, which might otherwise go unnoticed. However, the choice of analyzing coherence based on phases and amplitudes (amplitude-weighted phase coherence) vs only phases (phase coherence) has long been seen as arbitrary. Here, we review the concept of coherence and focus on time-localized methods of analysis, considering both phase coherence and amplitude-weighted phase coherence. We discuss the importance of using time-localized analysis and illustrate the methods and their practicalities on both numerically modeled and real time-series. The results show that phase coherence is more robust than amplitude-weighted phase coherence to both noise perturbations and movement artifacts. The results also have wider implications for the analysis of real data and the interpretation of physical systems.

Stable laser resonators support three fundamental families of transverse modes: the Hermite, Laguerre, and Ince Gaussian modes. These modes are crucial for understanding complex resonators, beam propagation, and structured light. We experimentally observe a new family of fundamental laser modes in stable resonators: Boyer-Wolf Gaussian modes. By studying the isomorphism between laser cavities and quadratic Hamiltonians, we design a laser resonator equivalent to a quantum two-dimensional anisotropic harmonic oscillator with a 2:1 frequency ratio. The generated Boyer-Wolf Gaussian modes exhibit a parabolic structure and show remarkable agreement with our theoretical predictions. These modes are also eigenmodes of a 2:1 anisotropic gradient refractive index medium, suggesting their presence in any physical system with a 2:1 anisotropic quadratic potential. We identify a transition connecting Boyer-Wolf Gaussian modes to Weber nondiffractive parabolic beams. These new modes are foundational for structured light, and open exciting possibilities for applications in laser micromachining, particle micromanipulation, and optical communications.

Photobiomodulation (PBM) therapy on the brain employs red to near-infrared (NIR) light to treat various neurological and psychological disorders. The mechanism involves the activation of cytochrome c oxidase in the mitochondrial respiratory chain, thereby enhancing ATP synthesis. Additionally, light absorption by ion channels triggers the release of calcium ions, instigating the activation of transcription factors and subsequent gene expression. This cascade of events not only augments neuronal metabolic capacity but also orchestrates anti-oxidant, anti-inflammatory, and anti-apoptotic responses, fostering neurogenesis and synaptogenesis. It shows promise for treating conditions like dementia, stroke, brain trauma, Parkinson's disease, and depression, even enhancing cognitive functions in healthy individuals and eliciting growing interest within the medical community. However, delivering sufficient light to the brain through transcranial approaches poses a significant challenge due to its limited penetration into tissue, prompting an exploration of alternative delivery methods such as intracranial and intranasal approaches. This comprehensive review aims to explore the mechanisms through which PBM exerts its effects on the brain and provide a summary of notable preclinical investigations and clinical trials conducted on various brain disorders, highlighting PBM's potential as a therapeutic modality capable of effectively impeding disease progression within the organism-a task often elusive with conventional pharmacological interventions.

This article deals with lasers from their initial description to the most advanced applications in the treatment of benign prostate enlargement.

Coherent light sources emitting in the terahertz range are highly sought after for fundamental research and applications. Terahertz lasers rely on achieving population inversion. We demonstrate the generation of terahertz radiation using nitrogen-vacancy centers in a diamond single crystal. Population inversion is achieved through the Zeeman splitting of the S = 1 state in 15 tesla, resulting in a splitting of 0.42 terahertz, where the middle Sz = 0 sublevel is selectively pumped by visible light. To detect the terahertz radiation, we use a phase-sensitive terahertz setup, optimized for electron spin resonance (ESR) measurements. We determine the spin-lattice relaxation time up to 15 tesla using the light-induced ESR measurement, which shows the dominance of phonon-mediated relaxation and the high efficacy of the population inversion. The terahertz radiation is tunable by the magnetic field, thus these findings may lead to the next generation of tunable coherent terahertz sources.