Stimulated emission and lasing of GaN-based laser diodes(LDs)were reported at 1995[1]and 1996[2],right after the breakthrough of p-type doping[3−5],material quality[6]and the invention of high-brightness GaN-based LED...Stimulated emission and lasing of GaN-based laser diodes(LDs)were reported at 1995[1]and 1996[2],right after the breakthrough of p-type doping[3−5],material quality[6]and the invention of high-brightness GaN-based LEDs[7,8].However,it took much longer time for GaN-based LDs to achieve high power,high wall plug efficiency,and long lifetime.Until 2019,Nichia reported blue LDs with these performances[9],which open wide applications with GaN-based blue LDs.展开更多
In this work,we reported the room-temperature continuous-wave operation of 6.0 W GaN-based blue laser diode(LD),and its stimulated emission wavelength is around 442 nm.The GaN-based high power blue LD is grown on a c-...In this work,we reported the room-temperature continuous-wave operation of 6.0 W GaN-based blue laser diode(LD),and its stimulated emission wavelength is around 442 nm.The GaN-based high power blue LD is grown on a c-plane GaN substrate by metal organic chemical vapor deposition(MOCVD),and the width and length of the ridge waveguide structure are 30 and 1200μm,respectively.The threshold current is about 400 mA,and corresponding threshold current density is 1.1 kA/cm2.展开更多
Electroluminescence （EL） and temperature-dependent photolumineseenee measurements are performed to study the internal quantum efficiency droop phenomenon of blue laser diodes （LDs） before lasing. Based on the ABC ...Electroluminescence （EL） and temperature-dependent photolumineseenee measurements are performed to study the internal quantum efficiency droop phenomenon of blue laser diodes （LDs） before lasing. Based on the ABC mode, the EL result demonstrates that non-radiative recombination rates of LDs with threshold current densities of 4 and 6kA/cm2 are similar, while LD with threshold current density of 4kA/cm2 exhibits a smaller auger- like recombination rate compared with the one of 6kA/cm2. The internal quantum efficiency droop is more serious for LD with higher threshold current density. temperature-dependent photoluminescence is consistent The internal quantum efficiency value estimated from with EL measurements.展开更多
BACKGROUND No studies have yet been conducted on changes in microcirculatory hemody-namics of colorectal adenomas in vivo under endoscopy.The microcirculation of the colorectal adenoma could be observed in vivo by a n...BACKGROUND No studies have yet been conducted on changes in microcirculatory hemody-namics of colorectal adenomas in vivo under endoscopy.The microcirculation of the colorectal adenoma could be observed in vivo by a novel high-resolution magnification endoscopy with blue laser imaging(BLI),thus providing a new insight into the microcirculation of early colon tumors.AIM To observe the superficial microcirculation of colorectal adenomas using the novel magnifying colonoscope with BLI and quantitatively analyzed the changes in hemodynamic parameters.METHODS From October 2019 to January 2020,11 patients were screened for colon adenomas with the novel high-resolution magnification endoscope with BLI.Video images were recorded and processed with Adobe Premiere,Adobe Photoshop and Image-pro Plus software.Four microcirculation parameters:Microcirculation vessel density(MVD),mean vessel width(MVW)with width standard deviation(WSD),and blood flow velocity(BFV),were calculated for adenomas and the surrounding normal mucosa.RESULTS A total of 16 adenomas were identified.Compared with the normal surrounding mucosa,the superficial vessel density in the adenomas was decreased(MVD:0.95±0.18 vs 1.17±0.28μm/μm2,P<0.05).MVW(5.11±1.19 vs 4.16±0.76μm,P<0.05)and WSD(11.94±3.44 vs 9.04±3.74,P<0.05)were both increased.BFV slowed in the adenomas(709.74±213.28 vs 1256.51±383.31μm/s,P<0.05).CONCLUSION The novel high-resolution magnification endoscope with BLI can be used for in vivo study of adenoma superficial microcirculation.Superficial vessel density was decreased,more irregular,with slower blood flow.展开更多
<div style="text-align:justify;"> An intracavity frequency doubling acousto-optically Q-switched Neodymium-doped Yttrium Orthvanadate (Nd:YVO<sub>4</sub>) 457 nm blue laser by employing a t...<div style="text-align:justify;"> An intracavity frequency doubling acousto-optically Q-switched Neodymium-doped Yttrium Orthvanadate (Nd:YVO<sub>4</sub>) 457 nm blue laser by employing a three-mirror folded cavity was demonstrated. With the incident pump power of 40.4 W, the maximum average output power of 439 mW 457 nm laser, and the minimum pulse duration of 86.14 ns and the maximum peak power of 510 W were achieved at 10 kHz. The M<sup>2</sup> factors are 1.23 and 1.61 in X and Y directions, respectively. The power stability in two hours is better than 2%. </div>展开更多
The possible ways and progress of infrared or red laser pumped green and blue laser emissions from a single solid state material doped by rare earth ions are outlined. The green and blue lasers realized from infrared ...The possible ways and progress of infrared or red laser pumped green and blue laser emissions from a single solid state material doped by rare earth ions are outlined. The green and blue lasers realized from infrared laser pumped rare earth doped nonlinear laser crystals by means of self frequency conversion and from infrared laser pumped rare earth doped bulk, fiber and microsphere materials by means of frequency upconversion are introduced in detail. Other kinds of devices and methods are also compared. The typical nonlinear laser crystals such as YAl 3(BO 3) 4, GdAl 3(BO 3) 4, YCa 4O(BO 3) 3 , GdCa 4O(BO 3) 3, and the typical upconversion fluoride fibers are compared and analyzed. The major problems remaining to be solved and the developing trends in the area are also discussed.展开更多
We propose and experimentally demonstrate a recorded 1-m bidirectional 20.231-Gbit/s tricolor R/G/B laser diode(LD) based visible-light communication(VLC) system supporting signal remodulation. In the signal remodulat...We propose and experimentally demonstrate a recorded 1-m bidirectional 20.231-Gbit/s tricolor R/G/B laser diode(LD) based visible-light communication(VLC) system supporting signal remodulation. In the signal remodulation system, an LD source is not needed at the client side. The client reuses the downstream signal sent from the central office(CO) and remodulates it to produce the upstream signal. As the LD sources are located at the CO, the laser wavelength and temperature managements at the cost-sensitive client side are not needed.This is the first demonstration, to our knowledge, of a >20 Gbit∕s data rate tricolor R/G/B VLC signal transmission supporting upstream remodulation.展开更多
Generation of a cavity-enhanced nondegenerate narrow-band photon pair source is a potential way to realize a perfect photonic quantum interface for a hybrid quantum network. However, to ensure the high quality of the ...Generation of a cavity-enhanced nondegenerate narrow-band photon pair source is a potential way to realize a perfect photonic quantum interface for a hybrid quantum network. However, to ensure the high quality of the photon source, the pump laser for the narrow-band photon source should be generated in a special way. Here, we experimentally generate the blue 453 nm laser with a sum frequency generation process in a periodically poled lithium niobate waveguide. A 13 mW laser at 453 nm can be achieved with a low-power 880 nm laser and 935 nm laser input, and the internal conversion efficiency is 21.6% after calculation. The frequency of a 453 nm laser is stabilized by locking two pump lasers on one ultrastable optical cavity. The single pass process without employ- ing cavity enhancement can ensure a good robustness of the whole system.展开更多
GaN-based continuous-wave operated blue-violet laser diodes(LDs) with long lifetime are demonstrated, which are grown on a c-plane GaN substrate by metal organic chemical vapor deposition with a 10 × 600 μm^2 ri...GaN-based continuous-wave operated blue-violet laser diodes(LDs) with long lifetime are demonstrated, which are grown on a c-plane GaN substrate by metal organic chemical vapor deposition with a 10 × 600 μm^2 ridge waveguide structure.The electrical and optical characteristics of a blue-violet LD are investigated under direct-current injection at room temperature(25 °C). The stimulated emission wavelength and peak optical power of the LD are around 413 nm and over 600 mW, respectively.In addition, the threshold current density and voltage are as small as 1.46 kA/cm^2 and 4.1 V, respectively. Moreover, the lifetime is longer than 1000 hours under room-temperature continuous-wave operation.展开更多
An NO2 photoacoustic sensor system with a high reflective mirror based on a low power blue diode laser is developed in this work. The excitation power is enhanced by increasing the number of reflections. Comparing wit...An NO2 photoacoustic sensor system with a high reflective mirror based on a low power blue diode laser is developed in this work. The excitation power is enhanced by increasing the number of reflections. Comparing with a traditional photoacoustic system, the pool constant is improved from 300.24(Pa·cm)/W to 1450.64(Pa·cm)/W, and the signal sensitivity of the photoacoustic sensor is increased from 0.016 μV/ppb to 0.2562 μV/ppb. The characteristics of temperature and humidity of the new photoacoustic sensor are also obtained, and the algorithm is adjusted to provide a quantitative response and drift of the resonance frequency. The results of this research provide a new method and concept for further developing the NO2 photoacoustic sensors.展开更多
We report a 42Ohm external cavity diode laser with an interference filter （IF） of 0.5am narrow-bandwidth and 79% high transmission, which is first used for Rb optical frequency standard. The IF and the cat-eye refle...We report a 42Ohm external cavity diode laser with an interference filter （IF） of 0.5am narrow-bandwidth and 79% high transmission, which is first used for Rb optical frequency standard. The IF and the cat-eye reflector are used for selecting wavelength and light feedback, respectively. The measured laser linewidth is 24 kHz when the diode laser is free running. Using this narrow-linewidth IF blue diode laser, we realize a compact Rb optical frequency standard without a complicated PDH system. The preliminary stability of the Rb optical frequency standard is 2 × 10^-13 at I s and decreases to 1.9 ×10^-14 at 1000s. The narrow-linewidth characteristic makes the IF blue diode laser a well suited candidate for the compact Rb optical frequency standard.展开更多
Toluidine blue(TB) is a good sensitizer for the polymerization of acrylnmide(AM) induced by He-Ne laser. With TB as a sensitizer and various alcoholamine as donors, the photoredox of TB and the polymerization kinetics...Toluidine blue(TB) is a good sensitizer for the polymerization of acrylnmide(AM) induced by He-Ne laser. With TB as a sensitizer and various alcoholamine as donors, the photoredox of TB and the polymerization kinetics of AM induced by He-Ne laser were investigated. It was found that either for the photoredox of TB or for the polymerization of AM, the activity of alcoholamine increases in the order of EOA<DEOA <TEOA in TB-alcoholamine sensitized system. The overall apparent kinetic equations of AM polymerization at 30℃ have been determined. In addition, the molecular weights under various conditions was measured.展开更多
AIM To describe the performance of 450 nm diode laser in oral surgery procedures.METHODS The case described consisted of the removal of a lower lip fibroma through a blue diode laser(λ = 450 nm). RESULTS The efficacy...AIM To describe the performance of 450 nm diode laser in oral surgery procedures.METHODS The case described consisted of the removal of a lower lip fibroma through a blue diode laser(λ = 450 nm). RESULTS The efficacy of this device, even at very low power(1W, CW), allows us to obtain very high intra and postoperative comfort for the patient, even with just topical anaesthesia and without needing suture. The healing process was completed in one week and, during the follow-up, the patient did not report any problems, pain or discomfort even without the consumption of any kind of drugs, such as painkillers and antibiotics. The histological examination performed by the pathologist showed a large area of fibrous connective tissue with some portions of epithelium-connective detachments and a regular incision with very scanty areas of carbonization.CONCLUSION The 450 nm diode laser proved of being very efficient in the oral soft tissue surgical procedures, with no side effects for the patients.展开更多
基金supported by the Natural Science Foundation of Jiangsu Province(Grant.BK20232042).
文摘Stimulated emission and lasing of GaN-based laser diodes(LDs)were reported at 1995[1]and 1996[2],right after the breakthrough of p-type doping[3−5],material quality[6]and the invention of high-brightness GaN-based LEDs[7,8].However,it took much longer time for GaN-based LDs to achieve high power,high wall plug efficiency,and long lifetime.Until 2019,Nichia reported blue LDs with these performances[9],which open wide applications with GaN-based blue LDs.
基金This work was supported by the National Key R&D Program of China(Grant Nos.2018YFB0406903,2017YFB0405001,2016YFB0400803 and 2016YFB0401801)the Science Challenge Project(Grant No.TZ2016003)+5 种基金the National Natural Science Foundation of China(Grant Nos.62034008,62074142,62074140,61974162,61904172,and 61874175)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2019115)Beijing Nova Program(Grant No.202093)Beijing Municipal Science and Technology Project(Grant No.Z161100002116037)Jiangsu Institute of Advanced Semiconductors(IASEMI 2020-CRP-02)Young Elite Scientists Sponsorship Program by CAST.
文摘In this work,we reported the room-temperature continuous-wave operation of 6.0 W GaN-based blue laser diode(LD),and its stimulated emission wavelength is around 442 nm.The GaN-based high power blue LD is grown on a c-plane GaN substrate by metal organic chemical vapor deposition(MOCVD),and the width and length of the ridge waveguide structure are 30 and 1200μm,respectively.The threshold current is about 400 mA,and corresponding threshold current density is 1.1 kA/cm2.
基金Supported by the National Key Research and Development Program of China under Grant Nos 2016YFB0401803 and 2016YFB0402002the National Natural Science Foundation of China under Grant Nos 61574160 and 61334005+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No XDA09020401the Visiting Professorship for Senior International Scientists of the Chinese Academy of Sciences under Grant No 2013T2J0048
文摘Electroluminescence （EL） and temperature-dependent photolumineseenee measurements are performed to study the internal quantum efficiency droop phenomenon of blue laser diodes （LDs） before lasing. Based on the ABC mode, the EL result demonstrates that non-radiative recombination rates of LDs with threshold current densities of 4 and 6kA/cm2 are similar, while LD with threshold current density of 4kA/cm2 exhibits a smaller auger- like recombination rate compared with the one of 6kA/cm2. The internal quantum efficiency droop is more serious for LD with higher threshold current density. temperature-dependent photoluminescence is consistent The internal quantum efficiency value estimated from with EL measurements.
基金This study was approved by the Medical Ethics Committee of Beijing Tsinghua Changgung Hospital(20002-0-02).
文摘BACKGROUND No studies have yet been conducted on changes in microcirculatory hemody-namics of colorectal adenomas in vivo under endoscopy.The microcirculation of the colorectal adenoma could be observed in vivo by a novel high-resolution magnification endoscopy with blue laser imaging(BLI),thus providing a new insight into the microcirculation of early colon tumors.AIM To observe the superficial microcirculation of colorectal adenomas using the novel magnifying colonoscope with BLI and quantitatively analyzed the changes in hemodynamic parameters.METHODS From October 2019 to January 2020,11 patients were screened for colon adenomas with the novel high-resolution magnification endoscope with BLI.Video images were recorded and processed with Adobe Premiere,Adobe Photoshop and Image-pro Plus software.Four microcirculation parameters:Microcirculation vessel density(MVD),mean vessel width(MVW)with width standard deviation(WSD),and blood flow velocity(BFV),were calculated for adenomas and the surrounding normal mucosa.RESULTS A total of 16 adenomas were identified.Compared with the normal surrounding mucosa,the superficial vessel density in the adenomas was decreased(MVD:0.95±0.18 vs 1.17±0.28μm/μm2,P<0.05).MVW(5.11±1.19 vs 4.16±0.76μm,P<0.05)and WSD(11.94±3.44 vs 9.04±3.74,P<0.05)were both increased.BFV slowed in the adenomas(709.74±213.28 vs 1256.51±383.31μm/s,P<0.05).CONCLUSION The novel high-resolution magnification endoscope with BLI can be used for in vivo study of adenoma superficial microcirculation.Superficial vessel density was decreased,more irregular,with slower blood flow.
文摘<div style="text-align:justify;"> An intracavity frequency doubling acousto-optically Q-switched Neodymium-doped Yttrium Orthvanadate (Nd:YVO<sub>4</sub>) 457 nm blue laser by employing a three-mirror folded cavity was demonstrated. With the incident pump power of 40.4 W, the maximum average output power of 439 mW 457 nm laser, and the minimum pulse duration of 86.14 ns and the maximum peak power of 510 W were achieved at 10 kHz. The M<sup>2</sup> factors are 1.23 and 1.61 in X and Y directions, respectively. The power stability in two hours is better than 2%. </div>
文摘The possible ways and progress of infrared or red laser pumped green and blue laser emissions from a single solid state material doped by rare earth ions are outlined. The green and blue lasers realized from infrared laser pumped rare earth doped nonlinear laser crystals by means of self frequency conversion and from infrared laser pumped rare earth doped bulk, fiber and microsphere materials by means of frequency upconversion are introduced in detail. Other kinds of devices and methods are also compared. The typical nonlinear laser crystals such as YAl 3(BO 3) 4, GdAl 3(BO 3) 4, YCa 4O(BO 3) 3 , GdCa 4O(BO 3) 3, and the typical upconversion fluoride fibers are compared and analyzed. The major problems remaining to be solved and the developing trends in the area are also discussed.
基金Ministry of Science and Technology,Taiwan(MOST)(MOST-106-2221-E-009-105-MY3)Aim for the Top University PlanMinistry of Education(MOE),Taiwan,China
文摘We propose and experimentally demonstrate a recorded 1-m bidirectional 20.231-Gbit/s tricolor R/G/B laser diode(LD) based visible-light communication(VLC) system supporting signal remodulation. In the signal remodulation system, an LD source is not needed at the client side. The client reuses the downstream signal sent from the central office(CO) and remodulates it to produce the upstream signal. As the LD sources are located at the CO, the laser wavelength and temperature managements at the cost-sensitive client side are not needed.This is the first demonstration, to our knowledge, of a >20 Gbit∕s data rate tricolor R/G/B VLC signal transmission supporting upstream remodulation.
基金supported by the National Key Research and Development Program of China(No.2017YFA0304100)the National Natural Science Foundation of China(Nos.61327901,11325419,and11474268)+2 种基金the Key Research Program of Frontier Sciences,CAS(No.QYZDY-SSW-SLH003)the National Program for Support of Topnotch Young Professionals(No.BB2470000005)the Fundamental Research Funds for the Central Universities(Nos.WK2470000026and WK2470000018)
文摘Generation of a cavity-enhanced nondegenerate narrow-band photon pair source is a potential way to realize a perfect photonic quantum interface for a hybrid quantum network. However, to ensure the high quality of the photon source, the pump laser for the narrow-band photon source should be generated in a special way. Here, we experimentally generate the blue 453 nm laser with a sum frequency generation process in a periodically poled lithium niobate waveguide. A 13 mW laser at 453 nm can be achieved with a low-power 880 nm laser and 935 nm laser input, and the internal conversion efficiency is 21.6% after calculation. The frequency of a 453 nm laser is stabilized by locking two pump lasers on one ultrastable optical cavity. The single pass process without employ- ing cavity enhancement can ensure a good robustness of the whole system.
基金supported by the National Key R&D Program of China (Nos. 2016YFB0401801, 2016YFB0400803)the Science Challenge Project (No. TZ2016003)+1 种基金the National Natural Science Foundation of China (Nos. 61674138, 61674139, 61604145, 61574135, 61574134, 61474142, 61474110)the Beijing Municipal Science and Technology Project (No. Z161100002116037)
文摘GaN-based continuous-wave operated blue-violet laser diodes(LDs) with long lifetime are demonstrated, which are grown on a c-plane GaN substrate by metal organic chemical vapor deposition with a 10 × 600 μm^2 ridge waveguide structure.The electrical and optical characteristics of a blue-violet LD are investigated under direct-current injection at room temperature(25 °C). The stimulated emission wavelength and peak optical power of the LD are around 413 nm and over 600 mW, respectively.In addition, the threshold current density and voltage are as small as 1.46 kA/cm^2 and 4.1 V, respectively. Moreover, the lifetime is longer than 1000 hours under room-temperature continuous-wave operation.
基金National Natural Science Foundation of China(Grant Nos.91644107,61575206,51904009,and 41905130)National Key Research and Development Program of China(Grant Nos.2017YFC0209401,2017YFC0209403,and 2017YFC0209902)the Outstanding Young Talents Program of Anhui University,China(Grant No.gxyq2019022).
文摘An NO2 photoacoustic sensor system with a high reflective mirror based on a low power blue diode laser is developed in this work. The excitation power is enhanced by increasing the number of reflections. Comparing with a traditional photoacoustic system, the pool constant is improved from 300.24(Pa·cm)/W to 1450.64(Pa·cm)/W, and the signal sensitivity of the photoacoustic sensor is increased from 0.016 μV/ppb to 0.2562 μV/ppb. The characteristics of temperature and humidity of the new photoacoustic sensor are also obtained, and the algorithm is adjusted to provide a quantitative response and drift of the resonance frequency. The results of this research provide a new method and concept for further developing the NO2 photoacoustic sensors.
基金Supported by the China Academy of Space Technology Foundation under Grant No CAST-2015-5-10the National Hi-Tech Research and Development Programthe National Natural Science Foundation of China under Grant No 91436210
文摘We report a 42Ohm external cavity diode laser with an interference filter （IF） of 0.5am narrow-bandwidth and 79% high transmission, which is first used for Rb optical frequency standard. The IF and the cat-eye reflector are used for selecting wavelength and light feedback, respectively. The measured laser linewidth is 24 kHz when the diode laser is free running. Using this narrow-linewidth IF blue diode laser, we realize a compact Rb optical frequency standard without a complicated PDH system. The preliminary stability of the Rb optical frequency standard is 2 × 10^-13 at I s and decreases to 1.9 ×10^-14 at 1000s. The narrow-linewidth characteristic makes the IF blue diode laser a well suited candidate for the compact Rb optical frequency standard.
基金Supported by the National Natural Science Foundation of China
文摘Toluidine blue(TB) is a good sensitizer for the polymerization of acrylnmide(AM) induced by He-Ne laser. With TB as a sensitizer and various alcoholamine as donors, the photoredox of TB and the polymerization kinetics of AM induced by He-Ne laser were investigated. It was found that either for the photoredox of TB or for the polymerization of AM, the activity of alcoholamine increases in the order of EOA<DEOA <TEOA in TB-alcoholamine sensitized system. The overall apparent kinetic equations of AM polymerization at 30℃ have been determined. In addition, the molecular weights under various conditions was measured.
文摘AIM To describe the performance of 450 nm diode laser in oral surgery procedures.METHODS The case described consisted of the removal of a lower lip fibroma through a blue diode laser(λ = 450 nm). RESULTS The efficacy of this device, even at very low power(1W, CW), allows us to obtain very high intra and postoperative comfort for the patient, even with just topical anaesthesia and without needing suture. The healing process was completed in one week and, during the follow-up, the patient did not report any problems, pain or discomfort even without the consumption of any kind of drugs, such as painkillers and antibiotics. The histological examination performed by the pathologist showed a large area of fibrous connective tissue with some portions of epithelium-connective detachments and a regular incision with very scanty areas of carbonization.CONCLUSION The 450 nm diode laser proved of being very efficient in the oral soft tissue surgical procedures, with no side effects for the patients.
