We demonstrate the temperature-dependent fluorescence properties of Pr：LiGdF4 crystal tor the first time, to the best of our knowledge, and its blue diode pumped cw red laser at 720 nm at room temperature. The fluore...We demonstrate the temperature-dependent fluorescence properties of Pr：LiGdF4 crystal tor the first time, to the best of our knowledge, and its blue diode pumped cw red laser at 720 nm at room temperature. The fluorescence lifetime and polarized emission cross sections in the visible range are measured and calculated in a temperature range from 77K to 300 K, and the variations of the fluorescence lifetime and spectra are discovered. The reasons for these changes are explained accordingly. The output wavelength of the 720nm laser is first reported on the laser performance by using a fiber-coupled laser diode at the wavelength of 442nm as the pump source, and the maximum cw output power is about 303roW.展开更多
The Kingdom of Saudi Arabia is one of the leading date producing countries. Unfortunately, this important fruit crop is under great threat from the red palm weevil （RPW） （Rhynchophorus ferrugineus）, which is a hig...The Kingdom of Saudi Arabia is one of the leading date producing countries. Unfortunately, this important fruit crop is under great threat from the red palm weevil （RPW） （Rhynchophorus ferrugineus）, which is a highly invasive pest. Several techniques, including visual inspection, acoustic sensors, sniffer dogs, and pheromone traps have been tried to detect the early stages of a RPW infestation; however, each method has suffered certain logistical and implementation issues. We have applied laser induced breakdown spectroscopy （LIBS） for the early detection of RPW infestation. Through the analysis of the observed LIBS spectra of different infested and healthy samples, we have found presence of Ca, Mg, Na, C, K elements and OH, CN molecules. The spectra also reveal that with the population growth of the pest, the intensity of Mg and Ca atomic lines in LIBS spectra increases rapidly. Similar behavior is observed in the molecular lines of LIBS spectra. The obtained results indicate that the LIBS technique can be used for the early detection of RPW infestation without damaging the date palms.展开更多
The characteristics of backward harmonic radiation due to electron oscillations driven by a linearly polarized fs laser pulse are analysed considering a single electron model. The spectral distributions of the electro...The characteristics of backward harmonic radiation due to electron oscillations driven by a linearly polarized fs laser pulse are analysed considering a single electron model. The spectral distributions of the electron＇s backward harmonic radiation are investigated in detail for different parameters of the driver laser pulse. Higher order harmonic radiations are possible for a sufficiently intense driving laser pulse. We have shown that for a realistic pulsed photon beam, the spectrum of the radiation is red shifted as well as broadened because of changes in the longitudinal velocity of the electrons during the laser pulse. These effects are more pronounced at higher laser intensities giving rise to higher order harmonics that eventually leads to a continuous spectrum. Numerical simulations have further shown that by increasing the laser pulse width the broadening of the high harmonic radiations can be controlled.展开更多
A theoretical study on the red-shift of laser-induced electro-absorption is presented. It is found that laser-induced red-shift scales with the cube root of the pump laser intensity in the optical tunneling regime and...A theoretical study on the red-shift of laser-induced electro-absorption is presented. It is found that laser-induced red-shift scales with the cube root of the pump laser intensity in the optical tunneling regime and has an obvious deviation from this scale in the multi-photon regime. Our results show that in the optical tunneling regime, the laser-induced red shift has the same law as that in the direct current （DC） approximation. Though the scales are the same in the optical tunneling regime, the physical pictures in the two cases are quite different. The electro-absorption in the DC case is a tunneling-assisted transition process, while the laser-induced electro-absorption is a mixed multi-photon process.展开更多
We report a high-power high-efficient continuous-wave （cw） diode-end-pumped Nd：YVO4 1342-nm laser with a short plane-parallel cavity and an efficient cw intracavity frequency-doubled red laser at 671 nm with a comp...We report a high-power high-efficient continuous-wave （cw） diode-end-pumped Nd：YVO4 1342-nm laser with a short plane-parallel cavity and an efficient cw intracavity frequency-doubled red laser at 671 nm with a compact three-element cavity. At incident pump power of 20.6 W, a maximum output power of 7 W at 1342 nm is obtained with a slope effciency of 37.3%. By inserting a type-Ⅰ critical phase-matched LBO crystal as intracavity frequencydoubler, a cw red output as much as 2.85-W is achieved with an incident pump power of 16.9 W, inducing an optical-to-optical conversion efficiency of 16.9%. To the best of our knowledge, this is the highest output of diodepumped solid-state Nd：YVO4 red laser. During half an hour, the red output is very stable, and the instability of output power is less than 1%.展开更多
AIM:To document the prognosis of laser treatment in patients with exudative age-related macular degeneration(AMD).· METHODS:Efficacy of the intervention was evaluated using a before-after method.· RESULTS:A ...AIM:To document the prognosis of laser treatment in patients with exudative age-related macular degeneration(AMD).· METHODS:Efficacy of the intervention was evaluated using a before-after method.· RESULTS:A total of 392 eyes of 341 patients with exudative AMD were examined.77.6% had choroideal neovascularisation(CNV).Before the use of indocyanine green(ICG) angiography,occult CNV was detected in only 1.8% of the eyes,but after the use of ICG angiography,this increased to 19.5%(P<0.001).Of the 349 eyes which were followed up,visual acuity had remained stable in 68.2% of the eyes.There was a statistically significant relationship between localisation of lesion and visual acuity changes on pre-and post-laser treatment(P<0.001).Also there was a statistically significant relationship between localisation of lesion and recurrence(P<0.05).The recurrence was less in subfoveal lesions than that in juxtafoveal and extrafoveal lesions.· CONCLUSION:ICG angiography is highly important in the treatment of occult CNV.展开更多
Laser-based displays have attracted much attention owing to large-size screen and full-color gamut compared with other displays such as liquid crystal display and light emitting diode. However, there exists a phenomen...Laser-based displays have attracted much attention owing to large-size screen and full-color gamut compared with other displays such as liquid crystal display and light emitting diode. However, there exists a phenomenon, speckle, limits the applications of laser display because of the high coherence of laser. In this work, we developed an electrically injected 6xx nm dual-emitter laser which combines the low-spatial coherence with the high-power. The output power of the dual-emitter laser exceeds 500 mW under 20?C pulse operation. The single emitter consists of D-shaped section used to obtain more independent spatial modes thus reduces coherence and a stripe area to obtain the high power. The radius of the D-shaped cavity is 500 μm and the length of stripe is 1000 μm. We used the standard photolithography and inductively coupled plasma (ICP) process to fabricate the device. The speckle contrast was measured to be 5%. It exhibits a great potential of reducing speckle from the source directly for laser display.展开更多
Burn injuries are common in Pakistan. However, most people are reluctant to have infrared treatment for their wounds. This study investigated the efficacy of infrared treatment on burn wounds. The procedure involved a...Burn injuries are common in Pakistan. However, most people are reluctant to have infrared treatment for their wounds. This study investigated the efficacy of infrared treatment on burn wounds. The procedure involved a burn victim who had sustained acid burns to the neck and face. Nectrotomy was done to remove dead tissue from the burn wound, and after treatment, Low-Level Light was used to reduce pain and enhance healing in the patient. Initial results showed mild hypertrophic scars, no stiffness. Post-operation therapy included physical training regimens and massage. The patient showed satisfactory results and felt less tightness in neck movements by the following treatment. The article concludes by showing that infrared light promoted repair and regrowth at a cellular level.展开更多
We present a study on a watt-level acousto-optically Q-switched Pr:YLF laser at three different repetition rates(10 kHz,20 kHz,and 50 kHz)for the first time,to the best of our knowledge.The corresponding average outpu...We present a study on a watt-level acousto-optically Q-switched Pr:YLF laser at three different repetition rates(10 kHz,20 kHz,and 50 kHz)for the first time,to the best of our knowledge.The corresponding average output powers and pulse widths were measured to be 1.14 W,1.2 W,and 1.32 W,and 40 ns,52 ns,and 80 ns,respectively.A maximum pulse energy of0.11 mJ was obtained,corresponding to a peak power of up to 2.8 kW at a repetition rate of 10 kHz.The simulated dynamics of a fast Q-switched Pr:YLF laser is in agreement with the experiment.The laser's ability to generate stable pulses with high peak power and short pulse width makes it highly desirable for various practical applications,such as laser machining and material processing.展开更多
目的:探讨点阵CO_(2)激光联合强脉冲光对痤疮后瘢痕患者的瘢痕面积、红肿面积及愈合时间的影响。方法:选取2020年1月-2020年12月于笔者医院就诊的90例痤疮后瘢痕患者为研究对象,按照随机数字表法分为两组。对照组(45例)行点阵CO_(2)激...目的:探讨点阵CO_(2)激光联合强脉冲光对痤疮后瘢痕患者的瘢痕面积、红肿面积及愈合时间的影响。方法:选取2020年1月-2020年12月于笔者医院就诊的90例痤疮后瘢痕患者为研究对象,按照随机数字表法分为两组。对照组(45例)行点阵CO_(2)激光治疗,研究组(46例)在对照组治疗基础上联合强脉冲光治疗。比较两组疗效、生活质量、痤疮瘢痕权重评分(Echelle d’evaluation clinique des cicatrices d’acne, ECCA)、瘢痕面积、红肿面积及愈合时间。结果:研究组总有效率93.48%,高于对照组73.33%,两组比较差异有统计学意义(P<0.05)。治疗后两组痤疮患者特异性生活质量问卷(Acne-specific quality of life questionnaire, Acne-QoL)各维度评分均高于治疗前,且研究组Acne-QoL各维度评分均高于对照组,差异有统计学意义(P<0.05)。治疗后两组ECCA评分均低于治疗前,且研究组ECCA评分低于对照组,差异均有统计学意义(P<0.05);治疗后两组瘢痕面积、红肿面积均小于治疗前(P<0.05),且研究组瘢痕面积、红肿面积小于对照组(P<0.05),研究组愈合时间短于对照组,差异均有统计学意义(P<0.05)。结论:点阵CO_(2)激光联合强脉冲光治疗痤疮后瘢痕有效率高,能改善患者生活质量与ECCA评分,缩小瘢痕面积及红肿面积,缩短愈合时间。展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 51025210,51102156 and 51272131the Young and Middle-Aged Scientists Research Awards Fund of Shandong Province under Grant No BS2011CL024
文摘We demonstrate the temperature-dependent fluorescence properties of Pr：LiGdF4 crystal tor the first time, to the best of our knowledge, and its blue diode pumped cw red laser at 720 nm at room temperature. The fluorescence lifetime and polarized emission cross sections in the visible range are measured and calculated in a temperature range from 77K to 300 K, and the variations of the fluorescence lifetime and spectra are discovered. The reasons for these changes are explained accordingly. The output wavelength of the 720nm laser is first reported on the laser performance by using a fiber-coupled laser diode at the wavelength of 442nm as the pump source, and the maximum cw output power is about 303roW.
基金supported by King Saud University, Deanship of Scientific Research, College of Science Research Center
文摘The Kingdom of Saudi Arabia is one of the leading date producing countries. Unfortunately, this important fruit crop is under great threat from the red palm weevil （RPW） （Rhynchophorus ferrugineus）, which is a highly invasive pest. Several techniques, including visual inspection, acoustic sensors, sniffer dogs, and pheromone traps have been tried to detect the early stages of a RPW infestation; however, each method has suffered certain logistical and implementation issues. We have applied laser induced breakdown spectroscopy （LIBS） for the early detection of RPW infestation. Through the analysis of the observed LIBS spectra of different infested and healthy samples, we have found presence of Ca, Mg, Na, C, K elements and OH, CN molecules. The spectra also reveal that with the population growth of the pest, the intensity of Mg and Ca atomic lines in LIBS spectra increases rapidly. Similar behavior is observed in the molecular lines of LIBS spectra. The obtained results indicate that the LIBS technique can be used for the early detection of RPW infestation without damaging the date palms.
基金supported by the National High-Tech ICF Committee of China (No.10335020/A0506)National Natural Science Foundation of China (Nos.10474081 and 10576035)Shanghai Natural Science Foundation (No.05ZR14159)
文摘The characteristics of backward harmonic radiation due to electron oscillations driven by a linearly polarized fs laser pulse are analysed considering a single electron model. The spectral distributions of the electron＇s backward harmonic radiation are investigated in detail for different parameters of the driver laser pulse. Higher order harmonic radiations are possible for a sufficiently intense driving laser pulse. We have shown that for a realistic pulsed photon beam, the spectrum of the radiation is red shifted as well as broadened because of changes in the longitudinal velocity of the electrons during the laser pulse. These effects are more pronounced at higher laser intensities giving rise to higher order harmonics that eventually leads to a continuous spectrum. Numerical simulations have further shown that by increasing the laser pulse width the broadening of the high harmonic radiations can be controlled.
基金Project supported by the Fundamental Research Funds for the Central Universities,China (Grant No.A735496)the National Natural Science Foundation of China (Grant No.61178018)the Ph.D. Funding Support Program of the Education Ministry of China (Grant No.20110185110007)
文摘A theoretical study on the red-shift of laser-induced electro-absorption is presented. It is found that laser-induced red-shift scales with the cube root of the pump laser intensity in the optical tunneling regime and has an obvious deviation from this scale in the multi-photon regime. Our results show that in the optical tunneling regime, the laser-induced red shift has the same law as that in the direct current （DC） approximation. Though the scales are the same in the optical tunneling regime, the physical pictures in the two cases are quite different. The electro-absorption in the DC case is a tunneling-assisted transition process, while the laser-induced electro-absorption is a mixed multi-photon process.
文摘We report a high-power high-efficient continuous-wave （cw） diode-end-pumped Nd：YVO4 1342-nm laser with a short plane-parallel cavity and an efficient cw intracavity frequency-doubled red laser at 671 nm with a compact three-element cavity. At incident pump power of 20.6 W, a maximum output power of 7 W at 1342 nm is obtained with a slope effciency of 37.3%. By inserting a type-Ⅰ critical phase-matched LBO crystal as intracavity frequencydoubler, a cw red output as much as 2.85-W is achieved with an incident pump power of 16.9 W, inducing an optical-to-optical conversion efficiency of 16.9%. To the best of our knowledge, this is the highest output of diodepumped solid-state Nd：YVO4 red laser. During half an hour, the red output is very stable, and the instability of output power is less than 1%.
文摘AIM:To document the prognosis of laser treatment in patients with exudative age-related macular degeneration(AMD).· METHODS:Efficacy of the intervention was evaluated using a before-after method.· RESULTS:A total of 392 eyes of 341 patients with exudative AMD were examined.77.6% had choroideal neovascularisation(CNV).Before the use of indocyanine green(ICG) angiography,occult CNV was detected in only 1.8% of the eyes,but after the use of ICG angiography,this increased to 19.5%(P<0.001).Of the 349 eyes which were followed up,visual acuity had remained stable in 68.2% of the eyes.There was a statistically significant relationship between localisation of lesion and visual acuity changes on pre-and post-laser treatment(P<0.001).Also there was a statistically significant relationship between localisation of lesion and recurrence(P<0.05).The recurrence was less in subfoveal lesions than that in juxtafoveal and extrafoveal lesions.· CONCLUSION:ICG angiography is highly important in the treatment of occult CNV.
文摘Laser-based displays have attracted much attention owing to large-size screen and full-color gamut compared with other displays such as liquid crystal display and light emitting diode. However, there exists a phenomenon, speckle, limits the applications of laser display because of the high coherence of laser. In this work, we developed an electrically injected 6xx nm dual-emitter laser which combines the low-spatial coherence with the high-power. The output power of the dual-emitter laser exceeds 500 mW under 20?C pulse operation. The single emitter consists of D-shaped section used to obtain more independent spatial modes thus reduces coherence and a stripe area to obtain the high power. The radius of the D-shaped cavity is 500 μm and the length of stripe is 1000 μm. We used the standard photolithography and inductively coupled plasma (ICP) process to fabricate the device. The speckle contrast was measured to be 5%. It exhibits a great potential of reducing speckle from the source directly for laser display.
文摘Burn injuries are common in Pakistan. However, most people are reluctant to have infrared treatment for their wounds. This study investigated the efficacy of infrared treatment on burn wounds. The procedure involved a burn victim who had sustained acid burns to the neck and face. Nectrotomy was done to remove dead tissue from the burn wound, and after treatment, Low-Level Light was used to reduce pain and enhance healing in the patient. Initial results showed mild hypertrophic scars, no stiffness. Post-operation therapy included physical training regimens and massage. The patient showed satisfactory results and felt less tightness in neck movements by the following treatment. The article concludes by showing that infrared light promoted repair and regrowth at a cellular level.
基金supported by the National Natural Science Foundation of China(No.61975168)。
文摘We present a study on a watt-level acousto-optically Q-switched Pr:YLF laser at three different repetition rates(10 kHz,20 kHz,and 50 kHz)for the first time,to the best of our knowledge.The corresponding average output powers and pulse widths were measured to be 1.14 W,1.2 W,and 1.32 W,and 40 ns,52 ns,and 80 ns,respectively.A maximum pulse energy of0.11 mJ was obtained,corresponding to a peak power of up to 2.8 kW at a repetition rate of 10 kHz.The simulated dynamics of a fast Q-switched Pr:YLF laser is in agreement with the experiment.The laser's ability to generate stable pulses with high peak power and short pulse width makes it highly desirable for various practical applications,such as laser machining and material processing.
文摘目的:探讨点阵CO_(2)激光联合强脉冲光对痤疮后瘢痕患者的瘢痕面积、红肿面积及愈合时间的影响。方法:选取2020年1月-2020年12月于笔者医院就诊的90例痤疮后瘢痕患者为研究对象,按照随机数字表法分为两组。对照组(45例)行点阵CO_(2)激光治疗,研究组(46例)在对照组治疗基础上联合强脉冲光治疗。比较两组疗效、生活质量、痤疮瘢痕权重评分(Echelle d’evaluation clinique des cicatrices d’acne, ECCA)、瘢痕面积、红肿面积及愈合时间。结果:研究组总有效率93.48%,高于对照组73.33%,两组比较差异有统计学意义(P<0.05)。治疗后两组痤疮患者特异性生活质量问卷(Acne-specific quality of life questionnaire, Acne-QoL)各维度评分均高于治疗前,且研究组Acne-QoL各维度评分均高于对照组,差异有统计学意义(P<0.05)。治疗后两组ECCA评分均低于治疗前,且研究组ECCA评分低于对照组,差异均有统计学意义(P<0.05);治疗后两组瘢痕面积、红肿面积均小于治疗前(P<0.05),且研究组瘢痕面积、红肿面积小于对照组(P<0.05),研究组愈合时间短于对照组,差异均有统计学意义(P<0.05)。结论:点阵CO_(2)激光联合强脉冲光治疗痤疮后瘢痕有效率高,能改善患者生活质量与ECCA评分,缩小瘢痕面积及红肿面积,缩短愈合时间。
