Development of fiber lasers, especially the latest progress in high power fiber lasers, and the problems of the commercialization of high power fiber lasers, are discussed. Research on other kinds of fiber lasers, suc...Development of fiber lasers, especially the latest progress in high power fiber lasers, and the problems of the commercialization of high power fiber lasers, are discussed. Research on other kinds of fiber lasers, such as microstructure fiber laser, ultrashort pulse fiber lasers, Raman fiber lasers are also involved.展开更多
An optical fiber bundle array coupling module with high output power is presented in this paper. The device integrated the coupling technique of the high power laser diode array (LDA) and the micro-ball lenses fiber a...An optical fiber bundle array coupling module with high output power is presented in this paper. The device integrated the coupling technique of the high power laser diode array (LDA) and the micro-ball lenses fiber array. This module can efficiently couple the output laser of the LDA into 19 fibers array with micro-ball lens end-surface. The difference of the couple efficiency between the flat-end fiber and micro-ball-end fiber is discussed. The micro-ball lenses fiber array made of 19 fibers have the same fiber core diameter of 200 m, and then the end-surfaces of 19 fibers are fused to 19 micro-ball lenses. The micro-ball lenses fiber array are fixed precisely in the neighborhood on the V-grooves, and the fiber array has the same arrange period with the semiconductor laser units of LDA. This configuration of micro-ball lens fiber array can greatly reduce the divergence of the laser beam from all directions, and a very efficient laser beam homogenizer and shaper are obtained. Finally, high output power of 30.1 W of the fiber coupled LDA is achieved, and the maximal coupling efficiency is >83% with the numeral aperture (NA) of 0.16.展开更多
During the COVID-19 epidemic in Wuhan,China,a series of measures were implemented by the government to prevent the spread of disease,including the lockdown policy and construction of emergency hospitals.To estimate th...During the COVID-19 epidemic in Wuhan,China,a series of measures were implemented by the government to prevent the spread of disease,including the lockdown policy and construction of emergency hospitals.To estimate the impact of these measures on aquatic environments,turbidity of lakes in Wuhan was dynamically monitored by integrating multi-sensor satellite observations.Calibrated against field measurements,empirical turbidity models were developed with high accuracy(R^(2)=0.77,RMSE=3.13 NTU).Time series of lake turbidity during COVID-19 were then retrieved,and possible factors for the turbidity change were discussed,including meteorological conditions and human activities.Results demonstrated that(1)the mean turbidity showed a 24.9%decline from 33.4 NTU to 25.1 NTU after the lockdown in Wuhan,which dropped 16.0%compared to that in the previous year.This decline might be related to the sharp reduction in human activities after the lockdown;(2)no obvious turbidity disturbance was observed in the lakes around emergency hospitals during their construction,and the lakes remained stable after the operation of hospitals.The method of integrating multi-sensor satellite observations used in this study shows great performance in term of temporal resolution for dynamic monitoring of inland water.展开更多
文摘Development of fiber lasers, especially the latest progress in high power fiber lasers, and the problems of the commercialization of high power fiber lasers, are discussed. Research on other kinds of fiber lasers, such as microstructure fiber laser, ultrashort pulse fiber lasers, Raman fiber lasers are also involved.
文摘An optical fiber bundle array coupling module with high output power is presented in this paper. The device integrated the coupling technique of the high power laser diode array (LDA) and the micro-ball lenses fiber array. This module can efficiently couple the output laser of the LDA into 19 fibers array with micro-ball lens end-surface. The difference of the couple efficiency between the flat-end fiber and micro-ball-end fiber is discussed. The micro-ball lenses fiber array made of 19 fibers have the same fiber core diameter of 200 m, and then the end-surfaces of 19 fibers are fused to 19 micro-ball lenses. The micro-ball lenses fiber array are fixed precisely in the neighborhood on the V-grooves, and the fiber array has the same arrange period with the semiconductor laser units of LDA. This configuration of micro-ball lens fiber array can greatly reduce the divergence of the laser beam from all directions, and a very efficient laser beam homogenizer and shaper are obtained. Finally, high output power of 30.1 W of the fiber coupled LDA is achieved, and the maximal coupling efficiency is >83% with the numeral aperture (NA) of 0.16.
基金supported by the National Key Research and Development Program of China[grant numbers 2018YFB0504900,2018YFB0504904 and 2016YFC0200900,2016YFC1400906]the National Natural Science Foundation of China[grant numbers 42071325,41701379 and 41571344]+3 种基金Wuhan University Luojia Talented Young Scholar project,Dragon 4 proposal ID 32442(entitled‘New Earth Observations tools for Water resource and quality monitoring in Yangtze wetlands and lakes(EOWAQYWET)’)LIESMARS Special Research Fundingthe‘985 Project’of Wuhan UniversitySpecial funds of State Key Laboratory for equipment.
文摘During the COVID-19 epidemic in Wuhan,China,a series of measures were implemented by the government to prevent the spread of disease,including the lockdown policy and construction of emergency hospitals.To estimate the impact of these measures on aquatic environments,turbidity of lakes in Wuhan was dynamically monitored by integrating multi-sensor satellite observations.Calibrated against field measurements,empirical turbidity models were developed with high accuracy(R^(2)=0.77,RMSE=3.13 NTU).Time series of lake turbidity during COVID-19 were then retrieved,and possible factors for the turbidity change were discussed,including meteorological conditions and human activities.Results demonstrated that(1)the mean turbidity showed a 24.9%decline from 33.4 NTU to 25.1 NTU after the lockdown in Wuhan,which dropped 16.0%compared to that in the previous year.This decline might be related to the sharp reduction in human activities after the lockdown;(2)no obvious turbidity disturbance was observed in the lakes around emergency hospitals during their construction,and the lakes remained stable after the operation of hospitals.The method of integrating multi-sensor satellite observations used in this study shows great performance in term of temporal resolution for dynamic monitoring of inland water.
