Usually GaAs/AlGaAs is utilized as an active layer material in laser diodes operating in the spectral range of 800- 850 nm. In this work, in addition to a traditional unstrained GaAs/AlGaAs distributed feedback （DFB...Usually GaAs/AlGaAs is utilized as an active layer material in laser diodes operating in the spectral range of 800- 850 nm. In this work, in addition to a traditional unstrained GaAs/AlGaAs distributed feedback （DFB） laser diode, a compressively strained InGaAlAs/AlGaAs DFB laser diode is numerically investigated in characteristic. The simulation results show that the compressively strained DFB laser diode has a lower transparency carrier density, higher gain, lower Auger recombination rate, and higher stimulated recombination rate, which lead to better a device performance, than the traditional unstrained GaAs/AlGaAs DFB laser diode.展开更多
Integrated electro-absorption-modulated distributed feedback laser diodes(EMLs)are attracting much interest in optical communications for the advantages of a compact structure,low power consumption,and high-speed modu...Integrated electro-absorption-modulated distributed feedback laser diodes(EMLs)are attracting much interest in optical communications for the advantages of a compact structure,low power consumption,and high-speed modulation.In integrated EML,the microwave interaction between the distributed feedback laser diode(DFB-LD)and the electro-absorption modulator(EAM)has a nonnegligible influence on the modulation performance,especially at the high-frequency region.In this paper,integrated EML was investigated as a three-port network with two electrical inputs and a single optical output,where the scattering matrix of the integrated device was theoretically deduced and experimentally measured.Based on the theoretical model and the measured data,the microwave equivalent circuit model of the integrated device was established,from which the microwave interaction between DFB-LD and EAM was successfully extracted.The results reveal that the microwave interaction within integrated EML contains both the electrical isolation and optical coupling.The electrical isolation is bidirectional while the optical coupling is directional,which aggravates the microwave interaction in the direction from DFB-LD to EAM.展开更多
A compact and highly linear quartz-enhanced photoacoustic spectroscopy（QEPAS） sensor for the measurement of water vapor concentration in the air is demonstrated. A cost-effective quartz tuning fork（QTF） is used as...A compact and highly linear quartz-enhanced photoacoustic spectroscopy（QEPAS） sensor for the measurement of water vapor concentration in the air is demonstrated. A cost-effective quartz tuning fork（QTF） is used as the sharp transducer to convert light energy into an electrical signal based on the piezoelectric effect, thereby removing the need for a photodetector. The short optical path featured by the proposed sensing system leads to a decreased size. Furthermore, a pair of microresonators is applied in the absorbance detection module（ADM） for QTF signal enhancement. Compared with the system without microresonators, the detected QTF signal is increased to approximately 7-fold. Using this optimized QEPAS sensor with the proper modulation frequency and depth, we measure the water vapor concentration in the air at atmospheric pressure and room temperature. The experimental result shows that the sensor has a high sensitivity of 1.058parts-per-million.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 10374085）. Acknowledgment The authors would like to thank the members of the nano-opotoelectronics laboratory for helpful discussion.
文摘Usually GaAs/AlGaAs is utilized as an active layer material in laser diodes operating in the spectral range of 800- 850 nm. In this work, in addition to a traditional unstrained GaAs/AlGaAs distributed feedback （DFB） laser diode, a compressively strained InGaAlAs/AlGaAs DFB laser diode is numerically investigated in characteristic. The simulation results show that the compressively strained DFB laser diode has a lower transparency carrier density, higher gain, lower Auger recombination rate, and higher stimulated recombination rate, which lead to better a device performance, than the traditional unstrained GaAs/AlGaAs DFB laser diode.
基金This work was supported by the National Key Research and Development Program of China under Grant No.2018YFE0201900the National Natural Science Foundation of China under Grants No.61927821 and No.61875240the Joint Research Fund of Ministry of Education of China under Grant No.6141A02022436.
文摘Integrated electro-absorption-modulated distributed feedback laser diodes(EMLs)are attracting much interest in optical communications for the advantages of a compact structure,low power consumption,and high-speed modulation.In integrated EML,the microwave interaction between the distributed feedback laser diode(DFB-LD)and the electro-absorption modulator(EAM)has a nonnegligible influence on the modulation performance,especially at the high-frequency region.In this paper,integrated EML was investigated as a three-port network with two electrical inputs and a single optical output,where the scattering matrix of the integrated device was theoretically deduced and experimentally measured.Based on the theoretical model and the measured data,the microwave equivalent circuit model of the integrated device was established,from which the microwave interaction between DFB-LD and EAM was successfully extracted.The results reveal that the microwave interaction within integrated EML contains both the electrical isolation and optical coupling.The electrical isolation is bidirectional while the optical coupling is directional,which aggravates the microwave interaction in the direction from DFB-LD to EAM.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61107070,61127018,and 61377071)
文摘A compact and highly linear quartz-enhanced photoacoustic spectroscopy（QEPAS） sensor for the measurement of water vapor concentration in the air is demonstrated. A cost-effective quartz tuning fork（QTF） is used as the sharp transducer to convert light energy into an electrical signal based on the piezoelectric effect, thereby removing the need for a photodetector. The short optical path featured by the proposed sensing system leads to a decreased size. Furthermore, a pair of microresonators is applied in the absorbance detection module（ADM） for QTF signal enhancement. Compared with the system without microresonators, the detected QTF signal is increased to approximately 7-fold. Using this optimized QEPAS sensor with the proper modulation frequency and depth, we measure the water vapor concentration in the air at atmospheric pressure and room temperature. The experimental result shows that the sensor has a high sensitivity of 1.058parts-per-million.
