Self-mixing interferometry with a terahertz Quantum Cascade Laser: Feedback induced voltage signal

We report here a compact and efficient sensing technique that utilises the self-mixing effect in terahertz Quantum Cascade Lasers (QCLs). A terahertz QCL is used both for the emission and the detection of light. Sensors based on this technique promise high sensitivity, simplicity of optical design and the potential for implementation in monolithic arrays.