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Low Threshold Quantum Cascade Lasers: From Laboratory to Industrialization

演讲课题:Low Threshold Quantum Cascade Lasers: From Laboratory to Industrialization

演讲人:刘峰奇Fengqi Liu

演讲摘要:

Quantum cascade lasers (QCLs) are semiconductor laser sources based on electron transitions between intersubbands of multiple well systems. Their unique operating principle and good performance have established themselves as the leading coherent semiconductor source in the infrared spectrum regimes, which is expected to find a variety of applications such as gas sensing, free-space communication and high-resolution spectroscopy. These applications require QCL with single-mode, low threshold and room-temperature continuous-wave (CW) operation. Here, we report some results on design, grown, fabrication and application of mid-infrared QCLs in the Institute of Semiconductors, Chinese Academy of Sciences. Room-temperature CW operation of QCLs emitting at 4.2-11 μm is presented. Two-phonon resonance, excited-state injection and bound-to-continuum in active region design combined with strain-compensation for material growth using molecular beam epitaxy (MBE) promise low threshold current density. Threshold current densities as low as 0.56, 0.5, 1.1 and 0.95 kA/cm2 for distributed feedback (DFB) QCLs emitting at 4.6, 4.9, 5.2 and 7.2 μm respectively in CW operation at 293 K were achieved for this state-of-the-art QCL [1-6]. The threshold power consumptions of DFB-QCLs can be reduced to 0.72 and 0.4 W at emitting wavelengths of λ ~ 4.9 and 5.2 μm respectively [5, 7]. The first quantum dot cascade laser operated at room temperature in CW mode with wavelength of 7.15 μm was achieved for improving the wall plug efficiency of QCL from the basic principle [8]. These fabricated devices have been widely used in automobile exhaust remote measurement, carbon dioxide isotope detection and other aspects.

刘峰奇Fengqi Liu

中国科学院半导体研究所

 Feng-Qi Liu received the B.S. degree in physics from Henan normal University, in 1985, the M.S. degree in solid state physics from University of Science and Technology of China, in 1990, and the Ph.D. degree in condensed matter physics from Nanjing University, in 1996. He joined Institute of Semiconductors, Chinese Academy of Sciences, in 1996, where his work has concentrated on the MBE growth and fabrication of high-performance mid-infrared and terahertz quantum cascade lasers. He received the National Natural Science Foundation for Distinguished Young Scholars in 2005, and the New Century National Hundred, Thousand and Ten Thousand Talent Project in 2007. Since strived for quantum cascade lasers in 1996, he has initiated and led the team for the development of QCLs step by step, and extended to THz-QCLs and quantum cascade detectors. His typical achievements are summarized as following: (1) He developed the first room temperature operated strain-compensated InGaAs/InAlAs QCL emitting at 3.5 mm in 2000. (2) He developed a series of room temperature (RT) continuous-wave (CW) operated high-performance QCLs with emitting wavelength in the range of 4.2--11 mm, for examples, RTCW of distributed feedback (DFB) QCLs with output power more than 1.2W, uncooled low threshold DFB-QCLs, and record low threshold electrical power consumption (0.4W) of substrate-emitting DFB-QCLs. (3) He innovated the first quantum dot cascade lasers by two-step strain compensation active region design. (4) He developed high power (1.37W) terahertz QCLs with emitting frequencies between 2.95~3.3 THz, and DFB THz-QCLs with record output power of 549 mW. (4) He developed a series of quantum cascade detectors in the detecting wavelength range of 4~19 mm with very low dark current and background noises, high operating temperature, and high detectivities. 

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