摘要
作为一种新型半导体激光器,量子级联激光器因其独特的子带间跃迁机制,具有高速响应、高非线性、输出波长大范围可调等特点。近年来随着输出光功率和电光转化效率等性能指标的快速提升,量子级联激光器已成为中红外至太赫兹波段(波长约为3~300μm)的主流激光光源,在大气污染监控、气体检测、太赫兹成像、生物医疗以及空间光通信等领域具有重要科学意义和应用价值。本文阐释了量子级联激光器的发展历程以及工作原理;分别重点讨论了中红外量子级联激光器在高效率、大功率、波长可调谐以及片上传感的应用等方面的研究进展,并对基于中红外量子级联激光器差频太赫兹光源和光频梳的发展进行叙述,最后进行了简要总结与展望。
Mid-infrared to terahertz spectral regions(3~300μm)are of particular interest to sensing and monitoring since a large number of gases such as CO,CH4,NH3,SO2,HCl,etc.,has strong characteristic vibrational transitions.These molecular fingerprints enables fast and pricise detection when a high power laser and a sensitive detector is applied.A morden sensing system normally includes a separate laser,a detector,and a gas chamber,which makes the system rather bulky and expensive.A chip-based sensing system on the other hand,with all the components integrated on a single chip,will greatly reduce the size,weight,power,and cost of the system.Currently,there are limited light source candidates for mid-infrared and terahertz sprectral bands.Devices that can generate light sources in the infrared band include:quantum well lasers,solid-state laser-pumped optical parametric oscillators,interband cascade lasers,and quantum cascade lasers.As a conventional semiconductor laser light source,quantum well laser is based on the optical transition between the conduction band electrons and valence band holes in the quantum wells,its emitting wavelength is determined by the band gap of the semiconductor quantum material.The photon energy in the mid-and far-infrared bands ranges from 0.04~0.4 eV,which is much smaller than the bandgap of the majority of quantum well laser materials themselves.It is difficult for traditional quantum well lasers to cover the mid-and far-infrared as well as terahertz bands.Devices using solid-state laser-pumped optical parametric oscillators to generate the mid-and far-infrared emission are generally large in size and low in efficiency,and have limitations in practical applications.In addition,based on cascade transition between the conduction band and the valence band,interband cascade lasers can cover the 3~6μm band.These type of laser is of much lower threshold current density and threshold power density.However,for the mid-infrared and even further wavelength bands,the performance of interband cascade lasers shows a decreasing trend.Based on intersubband transition in the conduction bands,Quantum Cascade Laser(QCL)is a new type of semiconductor laser source with high responsivity,high nonlinearity,and wide spectral coverage from mid-infrared to terahertz band.Compared with other laser sources that can produce mid-infrared sources,quantum cascade lasers have the advantages of small size,high energy efficiency,and wider wavelength tunability,and their wavelength ranges have been extended to the 3~25μm and 1~6 THz bands,which make them the most promising laser light sources in the midinfrared band.In recent years,quantum cascade lasers have important applications in the fields of long-range hazardous and explosive detection,biomedicine,infrared countermeasures and long-range free-space optical communications.Since the sensitivity and detecting range are proportional to the output power of the lasers,further improvement of the output power and electro-optical conversion efficiency of the devices is one of the most important goals of QCL research.By improving the device structure design,material epitaxial growth technology,and device preparation process,the output power,electro-optical conversion efficiency,beam quality,threshold current density,and other key parameters of quantum cascade lasers have been continuously optimized.In addition,broadly tuned,single-mode quantum cascade lasers with high side-mode suppression ratio have also become a research hotspot due to their urgent needs in gas sensing,spectroscopic measurements and other fields.Further,difference-frequency generation terahertz light sources and on-chip sensing technologies based on quantum cascade lasers are attracting more and more attention for the potential applications.With the recent rapid development in output power and wall-plug efficiency,QCL is becoming the most promising laser source in mid-IR and THz regions.The high power characteristic together with the strong absorption at zero bias makes QCL the ideal platform for on-chip sensing.This paper focuses on the recent development mid-infrared quantum cascade lasers and their application in on-chip sensing.Firstly,the history and working principle of quantum cascade lasers is introduced.Subsequently,the research progress of mid-infrared quantum cascade lasers in wall-plug efficiency,output power,wavelength tunability,single-mode operation,optical frequency comb,THz difference-frequency generation are summarized and their application in on-chip sensing are also discussed.
作者
周斌茹
马钰
张世晨
刘峰奇
陆全勇
ZHOU Binru;MA Yu;ZHANG Shichen;LIU Fengqi;LU Quanyong(Division of Quantum Materials and Devices,Beijing Academy of Quantum Information Sciences,Beijing 100193,China;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Semiconductor Materials Science,Institute of Semiconductors,Chinese Academy of Sciences,Beijing 100083,China)
出处
《光子学报》
EI
CAS
CSCD
北大核心
2023年第10期101-115,共15页
Acta Photonica Sinica
基金
国家自然科学基金(Nos.62274014,62235016)
北京市科学技术委员会(No.Z221100002722018)。
关键词
量子级联激光器
片上传感
光频梳
太赫兹
Quantum cascade lasers
On-chip sensing
Optical frequency comb
Terahertz
