Dual-comb interferometry using frequency shifting loops

Abstract

Dual-comb systems have demonstrated their potential for metrology, e.g. spectroscopy vibrometry or ranging [1], However, the implementation of dual-combs is often complex and generally requires substantial optical and optoelectronic hardware Here, we propose a simple and compact architecture based on a bidirectional frequency shifting loop, that provides more than I 00 mutually coherent comb lines The system makes use ofa CW laser and a slow electronic detection chain (10 MSa/s) We have implemented two configurations enabling dynamic multi-heterodyne interferometry at 20kHz: the first one makes use of acousto-optic frequency shifters, and allows highly sensitive distributed acoustic sensing along a fiber, The second one involves electro-optic frequency shifters, and enables ranging with a sub-mm resolution.