Robust integrated optical feedback interferometry via variable optical attenuation

Robust operation of optical feedback interferometry-based instruments requires controlling the amount of light that is reflected back into the laser. To this end, here we propose an on-chip optical feedback interferometry system with an integrated variable optical attenuator. We develop what we believe to be a novel analytical model for this system, and using a realistic variable optical attenuator design, we show that it can provide high precision displacement measurements in a wide range of the feedback parameter 2 < C < 100 for target distances up to a few centimeters. This paves the way towards short-distance applications in which reflections change significantly, such as the characterization of micro-electro-mechanical systems.