Phase-sensitive common-path dual frequency comb spectroscopy

Common-path dual comb spectroscopy using a single electro-optic modulator has been reported as a flexible, simple and low-cost symmetric dual comb configuration capable of measuring fine spectral signatures in the MHz regime with an extraordinarily high stability over acquisition times of seconds. However, the main drawback of symmetric dual comb configurations is that only the amplitude spectral response of the sample is obtained, losing any information from the phase spectral profile. In this work, we formulate and demonstrate, for the first time to our knowledge, an algorithm capable of extracting spectral phase information from a symmetric dual comb configuration. A phase reconstruction strategy based on the analysis of the spectral phase profile of high order Nyquist zones is performed. Our proposed algorithm is validated by extracting the transmission and phase profiles of a lossy fiber-based ring resonator.