Erzeugung von Terahertzstrahlung durch nichtlinear-optische Mischprozesse von kohärenter Mittelinfrarotstrahlung in Halbleiter-Wellenleiterstrukturen

本提案的目的是通过非线性光学（NLO）方法经由III-V族化合物半导体波导中的差频产生（DFG）直接产生相干连续波（CW）THz辐射，这是由于GaAs或InGaAs的二阶非线性光学极化率χ（2），即，泵浦频率ωP和信号频率ωS的波导内相互作用导致太赫兹范围内的闲频ωi = ωP - ωS。本文以量子级联激光器为光源，在~ 5-20μm的中红外波段对GaAs或InGaAs的二阶非线性进行了研究。非线性光学的一个关键要求，相位匹配，将通过光学异质结构中的形状双折射、准相位匹配（QPM）和模式极化激元相位匹配（PPM）来实现。工作程序包括两个实验的关键特征：a。通过外腔量子级联激光器配置实现中红外光谱域（约5至20 μm）的稳定相干双波长或双频光源，并具有良好控制的定制光谱性能。B.通过这两个频率在基于晶闸管的波导中的非线性光学相互作用产生有效的THz，包括对强反馈中的非线性光学过程的详细理解、建模和优化，以及与来自埃尔兰根和柏林的研究小组的技术合作伙伴的互动。

The aim of the present proposal is the direct generation of coherent continuous wave (CW) THz radiation by a nonlinear optical (NLO) approach via difference frequency generation (DFG) in III-V compound semiconductor waveguides due to the second order nonlinear optical susceptibility χ(2) of GaAs or InGaAs, i.e., the intra-waveguide interaction of a pump frequency ωP and a signal frequency ωS resulting in an idler frequency ωi = ωP - ωS in the THz range. Here, the second order non-linearity of GaAs or InGaAs will be explored in the mid-infrared (MIR) at ~ 5-20μm by powerful quantum cascade lasers as the laser source. One key requirement of NLO, phase matching, will be realised by form birefringence in optical heterostructures, quasi-phase matching (QPM) and modal polaritonic phase matching (PPM). The working program consists of two experimental key features: a. Realisation of a stable coherent two-wavelength or two-frequency source in the mid-infrared spectral domain (around 5 to 20 μm) with well-controlled tailored spectral performance by external cavity quantum cascade laser configurations. b. Efficient THz generation via nonlinear optical interaction of these two frequencies in semiconductor-based waveguides including a detailed understanding and modelling and optimisation of the nonlinear optical process in strong feedback and interaction with technology partners from the Forschergruppe in Erlangen and Berlin.