Robust control and stabilization of optical frequency combs enables an extraordinary range of scientific and technological applications, including frequency metrology at extreme levels of precision, novel spectroscopy of quantum gases and of molecules from visible wavelengths to the far infrared, searches for exoplanets, and photonic waveform synthesis. Here we report on the stabilization of a microresonator-based optical comb (microcomb) by way of mechanical actuation. This represents an important step in the development of microcomb technology, which offers a pathway toward fully integrated comb systems. Residual fluctuations of our 32.6 GHz microcomb line spacing reach a record stability level of 5 ×10-15 at 1 s, thereby highlighting the potential of microcombs to support modern optical frequency standards. Furthermore, measurements of the line spacing with respect to an independent frequency standard reveal the effective stabilization of different spectral slices of the comb with a <0.2 mHz variation among 140 comb lines. These results were achieved with fused-quartz microresonators fabricated using a newly-developed CO2-laser-machining technique.
Citation: Physical Review X
Pub Type: Journals
frequency stabilization, laser machining, microcomb, microresonator, optical clock, optical frequency comb