Princeton University

Jonas Westberg

Gerard Wysocki

Lukasz Sterczewski

Chu C Teng

According to various embodiments, a system for stabilizing operation of semiconductor laser frequency combs via optical feedback is disclosed. The system includes an external cavity having a beam-splitter, polarizer, and mirror or partially reflective element mounted on a translational stage. The external cavity and a laser facet of the semiconductor laser form an external optical resonator for coupling light to a laser cavity.

System and method for optical feedback stabilized semiconductor frequency combs

Disclosed herein is an all-digital phase and timing correction procedure for coherent averaging in dual-comb and multiheterodyne spectroscopy&#x2014;applicable to any dual-comb spectroscopy setup. It can account for large frequency/phase instabilities of the used sources, yielding a significant reduction of the noise pedestal and an increase in signal-to-noise ratio (SNR) of the radio frequency (RF) beat notes. This technique is computationally efficient and can be conveniently implemented either as a post-processing algorithm or in a real-time data acquisition and processing platform without the necessity of adding any additional optical elements to the dual-comb spectroscopy system. By implementing this technique, the performance of any comb- or comb-like-source-based DCS system with a sufficient degree of mutual coherence between the optical modes can be improved in terms of SNR and number of spectroscopically-usable RF beat notes. The described technique is compatible with a DC-centered RF spectrum, where the negative frequencies are folded to the positive domain to double the number of beat notes within the detector bandwidth. The technique enables coherent averaging over extended time-scales even for free-running combs, thus increasing the sensitivity of absorption and dispersion DCS measurements.

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Princeton, NJ, United States of America

Jonas Westberg