Precise spectroscopy of Er:YSiO based on laser frequency stabilization using a fiber laser comb.

Precise spectroscopy of the hyperfine level system of Er-doped YSiO was achieved in the frequency domain. By using an optical frequency comb to stabilize the light source frequency to an accuracy on the order of hertz on a long-term scale, Allan deviation < 10 Hz was achieved for an integration time of 180 s. As a result, spectral hole-burning experiments yielded a more accurate hole spectrum with a narrow homogeneous linewidth. The method opens the way to the straightforward exploration of relaxation mechanisms in the frequency domain by simple steady-state measurements.