Optical and Microwave Metrology at the 10⁻¹⁸ Level with an Er/Yb:glass Frequency Comb

Abstract

Optical frequency combs are essential tools for precision metrology experiments ranging in application from remote spectroscopic sensing of trace gases to the characterization and comparison of optical atomic clocks for precision time‐keeping and searches for physics beyond the standard model. Presented here is a description of the architecture and a full characterization of a telecom‐band, self‐modelocking frequency comb based on a free‐space laser with an Er/Yb co‐doped glass gain medium. The laser provides a robust and cost‐effective alternative to Er:fibre laser based frequency combs, while offering stability and noise performance similar to Ti:sapphire laser systems. Finally, the utility of the Er/Yb:glass frequency comb is demonstrated in high‐stability frequency synthesis using two ultra‐stable optical references at 1157 nm and 1070 nm and in low‐noise photonic microwave generation by dividing these references to the microwave domain.