Yellow Laser Research Articles

Growth and spectroscopic properties of Dy3+:GdCa4O(BO3)3 crystals

8 at.%, 10 at.%, and 12 at.% Dy3+ ions doped GdCa4O(BO3)3 crystals were successfully grown by the Czochralski method. The Raman spectrum showed that the maximum phonon energy was 937 cm−1. Detailed investigation of polarized absorption spectra, polarized fluorescence spectra, and fluorescence decay curve of the Dy3+:GCOB crystals showed that all the three crystals had good spectral properties. The strong and wide absorption peaks at 454 nm indicated that the crystals were fit for commercially available blue InGaN LD pumping. The intense and broad emission bands at around 585 nm, and long fluorescence lifetimes, revealed that the Dy3+:GCOB crystals were potential solid-state laser materials for yellow laser.

Ranibizumab Monotherapy versus Ranibizumab Combined with Adjuvant Subthreshold Micropulse Yellow Laser in Treatment of Diabetic Macular Edema

Ranibizumab Monotherapy versus Ranibizumab Combined with Adjuvant Subthreshold Micropulse Yellow Laser in Treatment of Diabetic Macular Edema

Evaluation of the effect of yellow laser (DPSS) light on human lymphocytes viability in vitro.

To evaluate the lymphocyte apoptotic impact of yellow laser light in vitro. The experimental study was conducted from November 2021 to April 2022 at the Postgraduate Medical Physics Laboratory, Mustansiriyah University, Baghdad, Iraq, and comprised blood samples from healthy volunteers. The samples were subjected to 1:1 dilution in isotonic phosphate buffered saline, and each sample was divided into two equal aliquots; one for irradiation, and other as control.The percentage of apoptotic lymphocyte was estimated before and after radiation exposure with low-level laser 589nm at 30J/cm², 50J/cm² and 70J/cm² energy intensities. Post-exposure evaluation was done immediately, and 1 and 2 hours after radiation on the viability of normal human cells. The vitality of the cells was determined using the trypan blue exclusion test. Data was analysed using SPSS 24. There were 26 healthy volunteers (16 male, 10 females) with an age range of (20-40) years. After the exposure, the percentage of lymphocytes that apoptose increased significantly when cells were irradiated at 70J/cm2 immediately compared to the controls (p≤ 0.05), but there was no significant differences with the 30J/cm² dose. After 1 and 2 hours, a significant reduction in the proportion of apoptotic lymphocytes was observed (p<0.05). Yellow low-level laser showed a noticeable protective effect on lymphocytes by decreasing the percentage of dead cells.

Effect of diode pumping solid state laser with wavelength 589 nm on gene expression of interlukine-2 and interferon-γ in human T-lymphocytes.

To evaluate the impact of laser irradiation of human T-cell lymphocyte in culture to determine the photobiomodulatory effects of such irradiation on gene expression, and the release of growth factors and cytokines. The experimental study was conducted from November 2021 to April 2022 at the Postgraduate Anatomy Laboratory, Mustansiriyah University, Baghdad, Iraq, and comprised human blood samples T-cell lymphocytes were extracted and irradiated, followed by the extraction of ribonucleic acid to assess the effect of laser on gene expression of cytokines, interlukine-2 and interferon-gamma. A 589nm yellow light low-level laser beam from a diode pumping solid state laser was used at doses 30J/cm2, 50J/cm2 and 70J/cm2 for an exposure time of 15 minutes. Reverse transcriptase-polymerase chain reaction was used to measure gene expression. Data was analysed using GraphPad Prism 9. Cellular gene expression of the mediators changed significantly in response to laser irradiation at a variety of dosage parameters, and these effects depended on the wavelength and radiation exposure (p<0.05). The laser light may photobiomodulate the production of cytokines by human cells in vitro.

Effect of 532nm and 589nm Diode-Pumped Solid-State (DPSS) Lasers with Different Doses on Concentration of Total Protein and Albumin in Vitro.

To test the effects of Low-level laser irradiation at 532nm and 589nm with different doses and exposure times on total protein and albumin in blood plasma. This experimental study was conducted from November 2021 to April 2022 at Mustansiriyah University, Baghdad, Iraq, and comprised blood samples from healthy adults. The samples were stored in tubes containing anticoagulant ethylenediaminetetraacetic acid. Photoradiation was managed using green laser 532nm and yellow laser 589nm diode-pumped solid-state lasers with different doses. For total protein test and albumin test, each sample was divided into 3 equal aliquots. The first was control without radiation, the second was irradiated by a laser at 532nm, and the third was irradiated at 589nm with 30J/cm², 50J/cm², 70J/cm² and 90 J/cm² doses of irradiation. All samples were examined by using a spectrophotometer device. Data was analysed using SPSS 25. There were 24 samples from healthy adults in all.The most significant difference in total protein concentration occurred at dose 70J/cm² for both wavelengths compared to the controls (p<0.05). When this optimal dose was applied to the albumin test, a clear decrease in the albumin concentration was found for both 532nm and 589nm lasers (p<0.05). At wavelengths of 532nm and 589nm, the laser light induced processes that caused a reduction in total protein and albumin.

The effect of a low-level yellow laser on improving the stability of stored whole blood.

To explore if low-level laser 589nm may stabilise stored whole blood and red blood cell suspension in vitro. The interventional study was conducted from November 2021 to April 2022 at the Postgraduate Medical Physics Laboratory, Mustansiriyah University, Baghdad, Iraq, and comprised blood samples from healthy adults. The samples were obtained put in tubes containing anticoagulant citrate-phosphate dextrose-adenine. Each sample was divided into eight equal aliquots and stored for 21 days at 4ºC. Of the 8 aliquots, 4 were takebn as controls, while the other 4 were irradiated by 589nm laser beam with a radiation dose of 50J/cm² for 15min. Stability test measured by the percentage of haemolysis of an overnight stored red blood cell in saline solution was done on days 0, 7, 14 and 21 for non-irradiated and radiated aliquots. Data was analysed using SPSS 24. Eight subjects (4 males and 4 females) were included, with mean age 21±3 years (range: 19-24 years). Whole blood samples showed a significant reduction in haemolysis by 40%, 20% and 42% compared to the control samples at days 0, 7 and 14, respectively (p<0.05). Red blood cell suspension showed a significant reduction in haemolysis by 9% compared to the control samples only at day 21 (p<0.05). Low-level laser 589nm beam at 50J/cm² radiation dose was more effective on the stability of stored whole blood than the red blood cell suspension.

First Achievement of Yellow Laser Operation in Dy3+-Doped Borate Crystals.

Continuous-wave (CW) yellow lasers have been demonstrated successfully by using a GaN laser-diode (LD) pumping in borate crystals for the first time. The Dy3+:GdMgB5O10 (Dy:GMB) crystal with dimensions up to 33 × 19 × 15 mm3 is grown by the top-seeded solution growth method, and the polarized spectroscopic properties are investigated systematically at room temperature. The line strengths, Judd-Ofelt (J-O) intensity, spontaneous transition rates, fluorescence branching ratios, and radiative lifetimes are calculated in detail by the Judd-Ofelt theory. Under direct pumping of 452 nm LD, a compact continuous-wave yellow laser with a maximum output power of 628 mW and laser wavelength of 581 nm is generated based on a Y-cut Dy:GMB crystal. To our knowledge, it is not only the highest output power for yellow laser obtained in Dy3+-doped crystals but also the first yellow laser operation achieved by borate crystals under direct LD pumping. The results reveal that the Dy:GMB crystal is an optical material with important application prospects in yellow laser.

Safety and efficacy of subthreshold micropulse yellow laser for persistent subretinal fluid after scleral bucking a randomized clinical trial

Persistent subretinal fluid (PSF) after scleral bucking of rhegmatogenous retinal detachment may delay recovery and affect the final visual quality, but with no effective treatment. This study firstly investigated the safety and efficacy of 577 nm yellow subthreshold micropulse laser (SML) on PSF after scleral bucking surgery. This double-masked randomized clinical trial was conducted from December 2020 to October 2022 at Chongqing Aier Eye Hospital. Participants with PSF last for 1 month after scleral bucking surgery with break closed and retina reattachment were recruitment. These participants were treated by 577 nm yellow SML or sham treatment. Funduscopy, optical coherence tomography (OCT) volume change, best corrected vision acuity (BCVA) and visual field test were evaluated for six mouths follow-up. A total of 24 participants were randomized into SML group or Sham group equally. Compared with Sham group, the OCT volume within 6 mm of macular fovea was significantly less in SML group 6 months after therapy (P = 0.048). There were no statistically significant differences of OCT volume at 1, 2 and 3 months from baseline between groups. BCVA of ETDRS letters had no statistically significant difference. Pattern Standard Deviation amelioration (P = 0.039) had statistically significance in SML group compared with Sham group. There were no complications in the 2 groups. These preliminary findings suggest that 577 nm yellow SML therapy could accelerate PSF absorption after scleral bucking surgery.Trial registration: Chinese Clinical Trial Registry No. ChiCTR2000037838, 02/09/2020, https://www.chictr.org.cn/showproj.html?proj=51885.

Comparison of two laser power levels in the subthreshold micropulse yellow laser treatment of acute central serous chorioretinopathy

AimsTo compare the efficacy of two power levels in the 577 nm sub-threshold micro pulse laser (SML) treatment of acute central serous chorioretinopathy (aCSC). MethodsA retrospective comparative study was conducted. A total of 65 patients (65 eyes) with aCSC were enrolled. Of which, 32 patients received low power treatment and 33 patients received high power treatment of 577 nm SML. Best-corrected visual acuity (BCVA), central macular thickness (CMT), fundus-monitored microperimetry and height of subfoveal choroidal thickness (SFCT) as well as subretinal fluid (SRF) were evaluated at baseline and 3 months. ResultsThe height of SFCT and retinal sensitivity in the low power treatment group was significantly better than that in the high power treatment group at 4 weeks (all p < 0.001). Mean BCVA improved from baseline to 3 months after treatments but with no significant difference between the two groups after 3 months (p > 0.05). In the low power group, the CMT decreased from 379.76 ± 139.23 μm at baseline to 176.56 ± 37.78 μm at 3 months, and in the high power group, the CMT decreased from 364.97 ± 143.08 at baseline to 191.77 ± 38.26 μm at 3 months. There was no significant difference at 3 months between the two groups (p > 0.05). Similar results were also found in term of SRF. ConclusionsTimely intervention with 577 nm SML with low power treatment can improve visual acuity, and included anatomic success without adverse events.

Management of Perifoveal Exudative Vascular Anomalous Complex.

To report a case of a patient with perifoveal exudative vascular anomalous complex (PEVAC) and to analyze morphological and vascular changes by OCT and OCTA before and after treatment. In this case we reported a case which received multiple treatment for unresponsive effect to Repeated Aflibercept intravitreal injections, subthreshold micropulse laser therapy (SMPL) duty cycle 5%. At last the focal fully dose yellow laser was performed. A 57-year-old male patient presented with best corrected visual acuity (BCVA) of 20/50 in his right eye (RE) The fundoscopic evaluation, structural optical coherence tomography (OCT) and OCT angiography (OCTA) deposed for a diagnosis of PEVAC. The patient underwent three Aflibercept intravitreal injections in the RE. Since no changes were detected, we opted for multiple sessions of yellow subthreshold micropulse laser therapy (SMPL) duty cycle 5%, however no signs of regression were registered. Only after a fully dose yellow laser, signs of edema regression were observed. Stuctural OCT B-scan showed complete restitutio of retinal profile, in absence of any intraretinal or subretinal fluid and PEVAC lesion, while the OCTA showed a slight flow deficit at the previous lesion site. and Importance: The PEVAC treatment is still unknown. In our experience, we reported a case of multiple treatments for unresponsive effect to: Aflibercept intravitreal injections, subthreshold micropulse laser therapy (SMPL) duty cycle 5%. At list the focal fully dose yellow laser was the only effective in our patient. We proposed our management to share the heterogeneous response at PEVAC entity.

Optical properties of Ce: GdYAG phosphor in glass with high quality LAS glass system and its application in laser illumination

Nowdays, the demand for high-power laser lighting applications is on the rise, however, phosphor in glass (PiG) prepared using conventional glass systems often experience damage under intense laser irradiation. To tackle this issue, we introduce a novel LAS glass system for phosphor encapsulation to create PiG, and by utilizing a spray coating technique, we blend PiG with high thermal conductivity sapphire to obtain phosphor in glass film (PiF), effectively improving laser irradiation resilience and optical characteristics. In this study, a novel LAS glass system (SiO2–Li2CO3–MgO–Al2O3–CaO–P2O5–K2O–ZrO2–Na2O) was utilized to encapsulate Ce:GdYAG phosphors to prepare a series of PiG and PiF. The glass system exhibits multi-directional interlocking lithium disilicate crystals, significantly enhancing the glass's strength and fracture toughness. There is no apparent interface reaction between the glass system and the phosphors, indicating effective protection of the phosphor particles. The PiF sample demonstrates a minor decrease of 5.2 % in internal quantum efficiency compared to the original phosphor, while boasting a high thermal conductivity of 7.4 W m−1 K−1. Notably, the optimized PiF shows remarkable enhancements with a saturation threshold of 4.37 W mm−2, surpassing PiG (1.668 W mm−2), and achieving LFmax of 424.41 lm and LEmax of 147.16 lm W−1. It features a high color rendering index (CRI) of 68.7 and low color correlated temperature (CCT) of 3646 K, significantly improving laser irradiation resistance and optical quality, making it a promising warm yellow laser illumination converter for diverse lighting applications.

Efficient yellow Dy:ZBLAN fiber laser with high-brightness diode-pumping at 450 nm.

We report on a low-threshold efficient yellow Dy-fiber laser with good beam quality featuring high-brightness pumping. It employs a single-clad 0.2 mol% Dy:ZBLAN fiber pumped by two 450-nm blue GaN laser diodes. The continuous-wave Dy-fiber laser delivers a maximum output power of 109 mW at 575 nm with a laser threshold of 218 mW, a slope efficiency of 19.6%, and beam quality factors M2 x,y ∼ 1.5. The overall optical efficiency versus incident pump power is 13.9%, being record-high, to the best of our knowledge, for this type of laser. The laser performance is simulated based on the spectroscopic data, being in good agreement with the experiment.

The investigations of yellow spectral performances in potentially efficient Dy3+:BaF2 and Dy3+/RE3+ (RE = Tb, Eu):BaF2 crystals

High quality Dy3+: BaF2 and Dy3+/RE3+ (RE = Tb, Eu): BaF2 crystals were successfully grown by temperature gradient technology (TGT). The visible spectroscopic properties as well as the energy transfer mechanism of Dy3+ and Tb3+/Eu3+ co-doped BaF2 crystals were systematically discussed. The spectral performance at 575 nm (Dy3+: 4F9/2 → 6H13/2) emission was significantly improved by co-doping Tb3+/Eu3+ ions. Through the upper level lifetime changed, it can be proved that there is a quasi resonance energy transfer between Dy3+: 6H13/2 and Tb3+: 7F4 / Eu3+: 7F4 states, and the final gain effect exceeds negative influence of the upper level energy transfer. Meanwhile, the optimal concentration ratio of Dy3+/Tb3+ and Dy3+/Eu3+ in double-doped crystals was relatively different. The optimal ratio of Dy3+/Tb3+ was 10:1 in 2%Dy3+,0.2%Tb3+: BaF2 crystal. The emission cross section increases from 8.147 × 10−22 cm2 to 11.284 × 10−22 cm2 with an increase of 38.5 %, and the quality factor (σem⋅τ) increases by 22.3 %. The optimal ratio of Dy3+/Eu3+ was 20:1 in 2%Dy3+,0.1%Eu3+: BaF2 crystal, the emission cross section is increased to 10.411 × 10−22 cm2 with an increase of 27.8 %, and the quality factor increases by 26.9 %. The above results show that Dy3+: BaF2 crystals co-doped with deactivated ions (Tb3+/Eu3+) of low concentration have great potential as gain media for yellow laser output.

Efficacy and Safety of 577-nm Yellow Laser in the Treatment of Pigmented Epidermal Lesions.

Freckles and lentigines are common pigmented problems which not only cause substantial cosmetic morbidity but also create psychosocial concern. The available modalities for the treatment of pigmented lesions are often unsatisfactory for patients, require a long treatment period, and often cause skin irritation. With the advent of lasers, safe and effective treatment options for epidermal pigmentation have become more varied for different Fitzpatrick skin types. We aimed to evaluate the efficacy and safety of 577-nm yellow laser in the treatment of pigmented epidermal lesions. This study was carried out on 50 patients presented with pigmented epidermal lesions (25 presented with freckles and 25 presented with lentigines). Each patient received four treatment sessions with a 577-nm diode laser at 2-week intervals. There was significant improvement in freckles and lentigines, as 23 out of 50 patients showed marked improvement, 11 patients showed moderate improvement, 10 patients showed mild improvement, and only six patients had no changes. Moreover, 23 patients were very satisfied, 18 patients were satisfied, and nine patients were not satisfied. As regards the safety of the 577-nm yellow laser, there was no significant adverse effect among patients except pain, erythema, and hyperpigmentation, which resolved within one month after treatment. This study showed that the 577-nm yellow laser is an effective, safe, and well-tolerated device in the treatment of freckles and lentigines.

Dy-Al-Ce codoped silica: a promising yellow laser glass with enhanced resistance to X-ray-induced photodarkening

To develop Dy doped silica glass with a higher irradiation resistance, which can be adapted to high power violet or blue LD pumped yellow laser fibers, the designed Dy-Al-Ce codoped silica glasses, 0.05Dy2O3-1.5Al2O3-xCe2O3-(98.45-x)SiO2 (x = 0, 0.05, 0.1, 0.25, 0.5), were prepared by the sol-gel method. Their excitation spectra, emission spectra and emission decay curves associated with the yellow emission from 4F9/2 to 6H13/2 of Dy were determined before and after the X-ray irradiation of 1000 Gy. The relation between these spectra and Ce-codoping concentrations is discussed, including the sensitization from Ce to Dy, the reverse energy transfer from Dy to Ce, and especially the X-ray-induced photodarkening, which is detrimental to the 576 nm yellow emission of Dy. The centers that cause the photodarkening are analyzed by electron paramagnetic resonance and radiation induced absorption spectra. It is found that Ce can effectively suppress the Al-oxygen hole center induced by the X-ray across the entire concentration range of Ce-codoping, but a new photodarkening center is generated at higher concentrations of Ce-codoping. Finally, the optimized Ce-codoping concentration of ∼0.1 mol% is used to achieve a promising yellow laser glass of Dy-Al-Ce codoped silica with enhanced irradiation resistance, resulting in its X-ray-induced photodarkening that is only 6% - 14% of that in the Ce-undoped.

Multiphonon-coupling yellow laser in Yb:La2CaB10O19 crystal

Yellow lasers at 590 nm have many extensive applications in our daily life, but extremely difficult to attain by traditional solid-state laser technology, owing to the absence of highly-efficient transition channels at this spectral range. In this work, we proposed a cooperative lasing mechanism to obtain the yellow light emission, with multiphonon-assisted electronic transitions and phase-matched frequency-doubling. Based on the predictable configurational coordinate model, we can calculate the multiphonon-assisted emission step-by-step. Using Yb3+-doped La2CaB10O19 crystal as an example, it is capable of producing yellow laser at 581–590 nm, with a maximum output power of 4.83 W and a high slope efficiency of 31.6%. To the best of our knowledge, it represents the highest power of solid-state yellow laser realized in one single crystal pumped by a laser diode. This power scaling can be assigned to the amplified phonon-assisted emission beyond the fluorescence spectrum, and optimized crystal angle for phase-matching condition. Such a compact, low-cost, and high-power laser device, provides an alternative candidate for the spectral “yellow-gap” where no practical solid-state laser exists at present.

Efficient sum-frequency generation of a yellow laser in a thin-film lithium niobate waveguide.

Yellow lasers with high efficiency and tunability play an essential role in many applications. Here, we demonstrate the sum-frequency generation (SFG) of yellow light on a periodically poled thin-film lithium niobate (PP-TFLN) waveguide. Taking advantage of large χ(2) nonlinearity, a high normalized conversion efficiency of 10,097% (W·cm2) is obtained with pump wavelengths of 1317.7 and 1064 nm. An absolute conversion efficiency of 24.17% is recorded with on-chip pump powers of 10.4 dBm (O-band) and 13.5 dBm (1064 nm).

Crystal growth and spectroscopic performances of Dy3+:YPO4 and Dy3+/Tb3+:YPO4 crystal as potential yellow laser gain mediums

Exploring new Dy3+-doped laser gain medium is still a challenge for constructing efficient yellow solid-state laser at current stage. In this paper, high quality Dy3+:YPO4 and Dy3+/Tb3+:YPO4 crystals were grown by the high temperature solution method. The crystal structure, chemical composition, phonon energy, polarized absorption and emission spectra, fluorescence lifetime were investigated. The obtained large FWHMs (6 nm) and absorption cross-sections (3.87×10−21 cm2) of Dy3+:YPO4 and Dy3+/Tb3+:YPO4 crystals at 454 nm indicate that they can be efficiently pumped by the commercial blue laser diodes. J-O intensity (Ω2, Ω4, Ω6), fluorescence branching rate and radiative lifetime of Dy3+ ions were calculated by J-O theory. Benefiting from the appropriate phonon energy, the emission cross-section of Dy3+: YPO4 crystal at 575 nm can reach 5.04×10−21 cm2. Moreover, after co-doping Tb3+ as deactivating ion, the emission cross-section of Dy3+/Tb3+: YPO4 crystal at 575 nm was promoted to 5.98×10−21 cm2 by a resonance energy transfer process between the Dy3+-6H13/2 and Tb3+-7F4. Therefore, both Dy3+:YPO4 and Dy3+/Tb3+:YPO4 crystals are potential candidates for yellow laser gain mediums.

High power and high efficiency yellow laser in Dy3+-doped single-mode double-clad structured waterproof fluoro-aluminate glass fiber

We demonstrated a single-mode yellow fiber laser using a Dy3+-doped single-mode double-clad structured weatherproof fluoro-aluminate glass fiber (Dy3+:SM-DC-WPFGF) and a 450-nm GaN laser diode (LD) as the excitation light. The power of 445 mW and the slope efficiency of 51.2% were achieved for the single-mode yellow fiber laser. The power level was approximately 20 times higher than our previous result due to improved efficiency of the focusing optics and increased Dy3+ doping concentration (10,000 ppm) in the fiber core. This yellow fiber laser shows particular promise for use in the medical field, e.g., for the treatment of melasma and telangiectasia.

Yellow diode laser 577 nm versus neodymium-doped yttrium aluminum garnet laser (Nd:Yag) in treating onychomycosis: A comparative study

Background Laser treatment signifies a safe option for managing Onychomycosis precisely in the presence of contraindication for antifungal drug use. Yellow Diode laser 577 nm has proved efficacy for managing different dermatological conditions as; vascular lesions, skin innovation and hair elimination. Nonetheless, it not yet been evaluated for treating Onychomycosis. Aim We aimed to evaluate the efficacy of Yellow Diode laser 577 nm in treating Onychomycosis and to compare the result with the use of long-pulsed Neodymium-doped Yttrium Aluminum Garnet (Nd:Yag) 1064 nm laser. Patients and methods Thirty patients diagnosed clinically and mycologically as having Onychomycosis were recruited. The right side of the treated hand was subjected to treatment by Yellow Diode laser 577 nm, while the left side of the treated hand was subjected to treatment by of long-pulsed Nd:Yag 1064 nm laser. All patients received 6 sessions (1 month apart). The results were evaluated clinically using the Onychomycosis Severity Index (OSI), photographically and mycologically. Results Complete recovery in the side treated by Yellow Diode laser 577 nm was observed in 7 (23.3%) patients, while the side treated by long-pulsed Nd:Yag 1064 nm laser showed complete recovery in 4 patients (13.3%), with significant difference between both sides (p value=0.015*). Conclusion Yellow Diode laser 577 nm is an effective safe and well-tolerated treatment option for managing Onychomycosis. It has proved better effectiveness than long-pulsed Nd;Yag 1064 nm laser in treating Onychomycosis.