Fast Spectroscopy Based on a Modulated Soliton Microcomb

Dissipative Kerr solitons (DKS)s offer an integrated platform for broad spectrum coverage, which is suitable for the high sensitivity spectroscopy. However, the large linespacing of the soliton comb limits the spectroscopy detection resolution. We overcome this limitation by modulating the soliton comb lines through an external EOMwith a tunable RF source. By locking the pump laser to a reference cavity, the linewidth of the pump laser was compressed from1.13 MHzto 72 kHz, leading to the silimar linewidth of comb lines and showing a frequency resolution of hundreds ofkHz. Based on the scannedmicrocomb, we measured the absorption spectra of a gas cell and the high-Q optical modes in themicrocavity, with a fast scanning speed of 16 GHz/mu s. The scanning comb allows the spectroscopy measurement to cover the whole comb mode spectrum over THz bandwidth. Our setup holds great potential for simple, robust spectroscopy measurement.

Automated summary

The study overcame the limitation of large linespacing in soliton comb, improving spectroscopy detection resolution. By locking the pump laser to a reference cavity, a high frequency resolution was achieved. Scanning the microcomb allowed fast measurement of gas absorption spectra and high-Q optical modes.