摘要
常规的分布式布拉格反射(DBR)半导体激光器中,增益区域所对应的自由谱间距应大于DBR高反射率带宽的1/2,以获得稳定的单模激射。该条件限制了DBR激光器的阈值和功率特性。文章首次提出并实现了基于DBR选模的太赫兹量子级联激光器(THz-QCL),并突破了上述限制。作者所实现的THz-QCL采用脊波导结构,利用解理腔面和DBR反射镜构成谐振腔,利用有源区增益谱较窄的特点,通过调整DBR反射率谱使增益谱与DBR高反射带在频域中部分重叠,从而获得了单模激射的THz-QCL。该方案使得DBR高反射带显著宽于自由谱间距,即显著提高了激光器中增益区域的长度,从而降低阈值并提高功率特性。实验上,作者研制出增益区域长达3.6 mm的DBR激光器,单模激射的频率为2.7 THz,边模抑制比达到25 dB,该激光器的阈值和温度特性与相同材料制备的法布里-泊罗腔多模激光器相当。文章中的工作为实现高性能单模太赫兹量子级联激光器提供了新的研究思路。
In the conventional semiconductor distributed Bragg reflector(DBR)lasers,to obtain stable single mode emission,the gain section should be short enough to make the free spectrum range larger than half of the bandwidth of the reflection plateau caused by the DBR.This constraint severely limits the threshold and the output power of the lasers.In this work,single mode terahertz DBR quantum cascade lasers(THz-DBR-QCLs)that break the above constraint are realized.The lasers are based on the ridge waveguide,and exploit a cleaved facet and a DBR mirror to construct the resonator.Exploiting the intrinsic narrow gain spectrum of the THz-QCL,we tailor the reflection spectrum of the DBR so that the high reflection plateau and the gain spectrum are partially overlapped,obtaining the THz-QCLs with single mode emission.Such strategy enables single mode emission with a significantly elongated gain section,far beyond the constraint of the free spectrum range.In experiments,we realize the single mode THz-DBR-QCLs,whose gain section is as long as 3.6 mm.The emission frequency is about 2.7 THz,and the side mode suppression ratio(SMSR)exceeds 25 dB.The measured threshold and temperature characteristics of the THz-DBR-QCLs are comparable to the Fabry-Perot THz-QCLs fabricated with the same material.Our work suggests a novel approach to realize the high performance single mode THz-QCLs.
作者
白弘宙
臧善志
谭诚
王凯
甘良华
徐刚毅
BAI Hong-Zhou;ZANG Shan-Zhi;TAN Cheng;WANG Kai;GAN Liang-Hua;XU Gang-Yi(Key Laboratory of Infrared Imaging Materials and Detectors,Shanghai Institute of Technical Physics,Chinese Academy of Sciences,Shanghai 200083,China;University of Chinese Academy of Sciences,Beijing 100049,China;School of Physics and Optoelectronic Engineering,Hangzhou Institute for Advanced Study,University of Chinese Academy of Sciences,Hangzhou 310024,China)
出处
《红外与毫米波学报》
SCIE
EI
CSCD
北大核心
2023年第6期796-806,共11页
Journal of Infrared and Millimeter Waves
基金
国家自然科学基金(61974151,67134006,61574149)
上海市科委项目(20ZR1466200)。
关键词
半导体激光器
量子级联
太赫兹
分布式布拉格反射镜
单模
光子禁带
semiconductor lasers
quantum cascade
terahertz
distributed Bragg reflector
single mode
photonic band gap
作者简介
白弘宙(1996-),男,河南濮阳人,博士生,主要研究领域为太赫兹量子级联激光器.E-mail:baihongzhou@mail.sitp.ac.cn;通讯作者:徐刚毅,E-mail:gangyi.xu@mail.sitp.ac.cn。
