Optomechanical response with nanometer resolution in the self-mixing signal of a terahertz quantum cascade laser

Abstract

The effectiveness of self-mixing interferometry has been demonstrated across the electromagnetic spectrum, from visible to microwave frequencies, in a plethora of sensing applications, ranging from distance measurement to material analysis, microscopy and coherent imaging. Owing to their intrinsic stability to optical feedback, quantum cascade lasers (QCLs) represent a source that offers unique and versatile characteristics to further improve the self-mixing functionality at mid infrared and terahertz (THz) frequencies. Here, we show the feasibility of detecting with nanometer precision deeply subwalength (