太赫兹量子级联激光器有源区增益分析和设计

Design of the active region gain of the terahertz quantum cascade lasers

太赫兹量子级联激光器(QCL)有源区设计主要包括啁啾超晶格、束缚-连续态跃迁和共振声子等模式。本文利用密度矩阵方法模拟太赫兹QCL光增益谱的基本特征,特别是通过分析太赫兹QCL光增益特性与子带寿命的依赖关系,理解太赫兹QCL对超晶格子带间非辐射跃迁寿命的要求。进而根据这些要求给出一种基于束缚-连续态跃迁和共振声子混合模式的太赫兹QCL有源区设计方案,利用纵光学声子共振帮助缩短束缚-连续态跃迁模式中下辐射态寿命。

Current active region designs of terahertz Quantum Cascade Lasers （QCL） include chirped superlattice, bound-to-continuum transition and resonant phonon modes. The density matrix method is employed to study the properties of gain of THz QCL, especially the dependences of the QCL＇s gain on the inter-subband transitions＇ lifetimes. Based on the analysis, an active region design of THz QCL based on bound-to-continuum transition with resonant phonon scattering extraction is presented, employing the longitudinal optical phonon scattering to shorten the lifetime of the lower radiation level of OCL.