A high-power and high-effciency GaAs/A1GaAs-based terahertz （THz） quantum cascade laser structure emitting at 3.3 THz is presented. The structure is based on a hybrid bound-to-continuum transition and resonant-phono...A high-power and high-effciency GaAs/A1GaAs-based terahertz （THz） quantum cascade laser structure emitting at 3.3 THz is presented. The structure is based on a hybrid bound-to-continuum transition and resonant-phonon extraction active region combined with a semi-insulating surface-plasmon waveguide. By optimizing material structure and device processing, the peak optical output power of 758mW with a threshold current density of 120 A/cm2 and a wall-plug effciency of 0.92% at 10K and 404mW at 77K are obtained in pulsed operation. The maximum operating temperature is as high as llS K. In the cw mode, a record optical output power of 160roW with a threshold current density of 178A/cm2 and a wall-plug efficiency of 1.32% is achieved at 1OK.展开更多
We report on the design and fabrication of λ-7.2μm distributed feedback quantum cascade lasers lot very high temperature cw operation and low electrical power consumption. The cw operation is reported above 90℃. Fo...We report on the design and fabrication of λ-7.2μm distributed feedback quantum cascade lasers lot very high temperature cw operation and low electrical power consumption. The cw operation is reported above 90℃. For a 2-mm-long and 10-μm-wide laser coated with high-reflectivity on the rear facet, more than 170mW of output power is obtained at 20℃ with a threshold power consumption of 2.4 W, corresponding to 30mW with a threshold power consumption of 3.9 W at 90℃. Robust single-mode emission with a side-mode suppression ratio above 25 dB is continuously tunable by the heat sink temperature or injection current.展开更多
We report an external cavity quantum cascade laser （EC-QCL） operating near 6.9μm using the Littman Metcalf configuration. The EC-QCL works in a pulsed mode and can be tuned continuously from 1340 to 1640cm^-1 by on...We report an external cavity quantum cascade laser （EC-QCL） operating near 6.9μm using the Littman Metcalf configuration. The EC-QCL works in a pulsed mode and can be tuned continuously from 1340 to 1640cm^-1 by only tilting the tuning mirror. The fine tuning ability of the EC-QCL is demonstrated by measuring the absorption spectrum of water in the ambient air with a lock-in amplifier.展开更多
We report an index-coupled distributed feedback quantum cascade laser by employing an equivalent phase shift(EPS) of quarter-wave integrated with a distributed Bragg reflector(DBR) at λ~5.03 μm. The EPS is fabricate...We report an index-coupled distributed feedback quantum cascade laser by employing an equivalent phase shift(EPS) of quarter-wave integrated with a distributed Bragg reflector(DBR) at λ~5.03 μm. The EPS is fabricated through extending one sampling period by 50% in the center of a sampled Bragg grating. The key EPS and DBR pattern are fabricated by conventional holographic exposure combined with the optical photolithography technology, which leads to improved flexibility, repeatability, and cost-effectiveness. Stable single-mode emission can be obtained by changing the injection current or heat sink temperature even under the condition of large driving pulse width.展开更多
In this paper, the author at first develops a method to study convergence of the cascadealgorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), andthen applies the previous result on th...In this paper, the author at first develops a method to study convergence of the cascadealgorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), andthen applies the previous result on the convergence to characterizing compactly supportedrefinable distributions in fractional Sobolev spaces and Holder continuous spaces (see Theorems3.1, 3.3, and 3.4). Finally the author applies the above characterization to choosing appropriateinitial to guarantee the convergence of the cascade algorithm (see Theorem 4.2).展开更多
The development of teranertz （THz） quantum cascade lasers （QCLs） has progressed considerably since their advent almost a decade ago.THz QCLs operating in a frequency range from 1.4 to 4 THz with electron-phonon sc...The development of teranertz （THz） quantum cascade lasers （QCLs） has progressed considerably since their advent almost a decade ago.THz QCLs operating in a frequency range from 1.4 to 4 THz with electron-phonon scattering mediated depopulation schemes are described.Several different types of GaAs/AlGaAs superlattice designs are reviewed.Some of the best temperature performances are obtained by the so-called resonant-phonon designs that are described.Operation above a temperature of 160 K has been obtained across the spectrum for THz QCLs operating at ν 〉 1.8 THz.The maximum operating temperature of previously reported THz QCLs has empirically been limited to a value of ～ω/k B.A new design scheme for THz QCLs with scattering-assisted injection is shown to surpass this empirical temperature barrier,and is promising to improve the maximum operating temperatures of THz QCLs even further.展开更多
基金Supported by the National Basic Research Program of China under Grant Nos 2014CB339803 and 2013CB632801the National Natural Science Foundation of China under Grant No 61376051
文摘A high-power and high-effciency GaAs/A1GaAs-based terahertz （THz） quantum cascade laser structure emitting at 3.3 THz is presented. The structure is based on a hybrid bound-to-continuum transition and resonant-phonon extraction active region combined with a semi-insulating surface-plasmon waveguide. By optimizing material structure and device processing, the peak optical output power of 758mW with a threshold current density of 120 A/cm2 and a wall-plug effciency of 0.92% at 10K and 404mW at 77K are obtained in pulsed operation. The maximum operating temperature is as high as llS K. In the cw mode, a record optical output power of 160roW with a threshold current density of 178A/cm2 and a wall-plug efficiency of 1.32% is achieved at 1OK.
基金Supported by the National Basic Research Program of China under Grant No 2013CB632801the National Key Research and Development Program under Grant No 2016YFB0402303+2 种基金the National Natural Science Foundation of China under Grant Nos61435014,61627822,61574136 and 61306058the Key Projects of Chinese Academy of Sciences under Grant No ZDRW-XH-2016-4the Beijing Natural Science Foundation under Grant No 4162060
文摘We report on the design and fabrication of λ-7.2μm distributed feedback quantum cascade lasers lot very high temperature cw operation and low electrical power consumption. The cw operation is reported above 90℃. For a 2-mm-long and 10-μm-wide laser coated with high-reflectivity on the rear facet, more than 170mW of output power is obtained at 20℃ with a threshold power consumption of 2.4 W, corresponding to 30mW with a threshold power consumption of 3.9 W at 90℃. Robust single-mode emission with a side-mode suppression ratio above 25 dB is continuously tunable by the heat sink temperature or injection current.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11174098 and 11574107the SelfDetermined Research Funds of Central China Normal University under Grant No CCNU15A02034
文摘We report an external cavity quantum cascade laser （EC-QCL） operating near 6.9μm using the Littman Metcalf configuration. The EC-QCL works in a pulsed mode and can be tuned continuously from 1340 to 1640cm^-1 by only tilting the tuning mirror. The fine tuning ability of the EC-QCL is demonstrated by measuring the absorption spectrum of water in the ambient air with a lock-in amplifier.
基金National Basic Research Program of China(2013CB632800)National Key Research and Development Program(2016YFB0402303)+2 种基金National Natural Science Foundation of China(NSFC)(61404131,61435014,61674144,61574136,61627822)Chinese Academy of Sciences Key Project(CAS Key Project)(QYZDJ-SSWJSC027,ZDRW-XH-2016-4)Natural Science Foundation of Beijing Municipality(4162060,4172060)
文摘We report an index-coupled distributed feedback quantum cascade laser by employing an equivalent phase shift(EPS) of quarter-wave integrated with a distributed Bragg reflector(DBR) at λ~5.03 μm. The EPS is fabricated through extending one sampling period by 50% in the center of a sampled Bragg grating. The key EPS and DBR pattern are fabricated by conventional holographic exposure combined with the optical photolithography technology, which leads to improved flexibility, repeatability, and cost-effectiveness. Stable single-mode emission can be obtained by changing the injection current or heat sink temperature even under the condition of large driving pulse width.
文摘In this paper, the author at first develops a method to study convergence of the cascadealgorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), andthen applies the previous result on the convergence to characterizing compactly supportedrefinable distributions in fractional Sobolev spaces and Holder continuous spaces (see Theorems3.1, 3.3, and 3.4). Finally the author applies the above characterization to choosing appropriateinitial to guarantee the convergence of the cascade algorithm (see Theorem 4.2).
基金supported by the National Aeronautics and Space Administration and the National Science Foundation
文摘The development of teranertz （THz） quantum cascade lasers （QCLs） has progressed considerably since their advent almost a decade ago.THz QCLs operating in a frequency range from 1.4 to 4 THz with electron-phonon scattering mediated depopulation schemes are described.Several different types of GaAs/AlGaAs superlattice designs are reviewed.Some of the best temperature performances are obtained by the so-called resonant-phonon designs that are described.Operation above a temperature of 160 K has been obtained across the spectrum for THz QCLs operating at ν 〉 1.8 THz.The maximum operating temperature of previously reported THz QCLs has empirically been limited to a value of ～ω/k B.A new design scheme for THz QCLs with scattering-assisted injection is shown to surpass this empirical temperature barrier,and is promising to improve the maximum operating temperatures of THz QCLs even further.
