Multidimensional influences of indium composition in barrier layers on GaN-based blue laser diodes(LDs)are discussed from both material quality and device physics perspectives.LDs with higher indium content in the bar...Multidimensional influences of indium composition in barrier layers on GaN-based blue laser diodes(LDs)are discussed from both material quality and device physics perspectives.LDs with higher indium content in the barriers demonstrate a notably lower threshold current and shorter lasing wavelength compared to those with lower indium content.Our experiments reveal that higher indium content in the barrier layers can partially reduce indium composition in the quantum wells,a novel discovery.Employing higher indium content barrier layers leads to improved luminescence properties of the MQW region.Detailed analysis reveals that this improvement can be attributed to better homogeneity in the indium composition of the well layers along the epitaxy direction.InGaN barrier layers suppress the lattice mismatch between barrier and well layers,thus mitigating the indium content pulling effect in the well layers.In supplement to experimental analysis,theoretical computations are performed,showing that InGaN barrier structures can effectively enhance carrier recombination efficiency and optical confinement of LD structure,thus improving the output efficiency of GaN-based blue LDs.Combining these theoretical insights with our experimental data,we propose that higher indium content barriers effectively enhance carrier recombination efficiency and indium content homogeneity in quantum well layers,thereby improving the output performance of GaN-based blue LDs.展开更多
Tunable diode laser absorption spectroscopy （TDLAS） has been widely employed in atmospheric trace gases detection. The ratio of the second-harmonic signal to the intensity of laser beam incident to the multi-pass ce...Tunable diode laser absorption spectroscopy （TDLAS） has been widely employed in atmospheric trace gases detection. The ratio of the second-harmonic signal to the intensity of laser beam incident to the multi-pass cell is proved to be proportional to the product of the path length and the gas concentration under any condition. A new calibration method based on this relation in TDLAS system for the measurement of trace gas concentration is proposed for the first time. The detection limit and the sensitivity of the system are below 110 and 31ppbv （parts-per-billion in volume）, respectively.展开更多
A real time α-β-γ filtering technique is applied to the monitoring of atmosphere CH4 based on a tunable diode laser spectrum system operating at 1.654μm. This technique is developed for improving the sensitivity a...A real time α-β-γ filtering technique is applied to the monitoring of atmosphere CH4 based on a tunable diode laser spectrum system operating at 1.654μm. This technique is developed for improving the sensitivity and precision of CH4 concentration measurement with slow concentration change. The effectiveness of this technique is evaluated by performing CH4 concentration measurement and using it to monitor the varying methane level in the atmosphere. It was proved that signal noise ratio enhancement factor is 4.25. The comparison between this filter and moving average is also included in this article. It indicates the advantage of the α-β-γ real time filter.展开更多
基金Project supported by Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2023124)the National Key Research and Development Program of China(Grant No.2022YFB3608100)+3 种基金Key Research and Development Program of Jiangsu Province(Grant No.BE2021008-1)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(Grant No.2022SXTD016)the National Natural Science Foundation of China(Grant Nos.62274157,61904172,62127807,62234011,61974162,62034008,62074142,62074140,and 62250038)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB43030101)。
文摘Multidimensional influences of indium composition in barrier layers on GaN-based blue laser diodes(LDs)are discussed from both material quality and device physics perspectives.LDs with higher indium content in the barriers demonstrate a notably lower threshold current and shorter lasing wavelength compared to those with lower indium content.Our experiments reveal that higher indium content in the barrier layers can partially reduce indium composition in the quantum wells,a novel discovery.Employing higher indium content barrier layers leads to improved luminescence properties of the MQW region.Detailed analysis reveals that this improvement can be attributed to better homogeneity in the indium composition of the well layers along the epitaxy direction.InGaN barrier layers suppress the lattice mismatch between barrier and well layers,thus mitigating the indium content pulling effect in the well layers.In supplement to experimental analysis,theoretical computations are performed,showing that InGaN barrier structures can effectively enhance carrier recombination efficiency and optical confinement of LD structure,thus improving the output efficiency of GaN-based blue LDs.Combining these theoretical insights with our experimental data,we propose that higher indium content barriers effectively enhance carrier recombination efficiency and indium content homogeneity in quantum well layers,thereby improving the output performance of GaN-based blue LDs.
基金Project supported by the National Natural Science Foundation of China （Grant No 10274080） and the National High Technology Research and Development Program of China （Grant No 2003AA641010）.
文摘Tunable diode laser absorption spectroscopy （TDLAS） has been widely employed in atmospheric trace gases detection. The ratio of the second-harmonic signal to the intensity of laser beam incident to the multi-pass cell is proved to be proportional to the product of the path length and the gas concentration under any condition. A new calibration method based on this relation in TDLAS system for the measurement of trace gas concentration is proposed for the first time. The detection limit and the sensitivity of the system are below 110 and 31ppbv （parts-per-billion in volume）, respectively.
基金Project supported by the National Natural Science Foundation of China （Grant No 10274080） and the National High Technology Research and Development Program of China （Grant No 2003AA641010）.
文摘A real time α-β-γ filtering technique is applied to the monitoring of atmosphere CH4 based on a tunable diode laser spectrum system operating at 1.654μm. This technique is developed for improving the sensitivity and precision of CH4 concentration measurement with slow concentration change. The effectiveness of this technique is evaluated by performing CH4 concentration measurement and using it to monitor the varying methane level in the atmosphere. It was proved that signal noise ratio enhancement factor is 4.25. The comparison between this filter and moving average is also included in this article. It indicates the advantage of the α-β-γ real time filter.
