Double-Sideband Electro-Optic Dual-Comb Spectroscopy Using One Modulator

Electro-optic (EO) dual-comb spectroscopy offers an attractive and flexible alternative to the traditional mode-locked laser approach, and has the unique potential to be implemented on photonic integrated chips. However, despite recent efforts on simplifying EO dual-comb configurations, such as using fewer modulators, optical filters or acousto-optic modulators (AOMs) that are still difficult to realize on chips have been indispensable to resolving the image frequency issue in EO combs. Here, a simple EO dual-comb spectroscopy scheme is proposed, which uses only one off-the-shelf modulator and no optical filters or AOMs while the bandwidth of the generated combs is fully utilized. In the scheme, two broadband driving signals with different comb spacings are applied to the modulator's arms, and the phase between the dual combs is tuned via a varying bias. The amplitudes at the image frequencies are then distinguished using interferograms under different phase biases. Demonstration of EO dual-comb spectroscopy with over 200 resolved comb teeth is achieved, driven by low-cost and compact RF comb generators. The scheme simplifies the EO setup and boosts power efficiency by leveraging the double-sideband EO comb spectra. It can be an attractive enabling solution of chip-integrated and cost-effective dual-comb devices.