Burning and reading ensembles of spectral holes by optical frequency combs: Demonstration in rare-earth-doped solids and application to laser frequency stabilization

Abstract

We describe a spectroscopic method applicable to inhomogeneously broadened transitions. As a test system we use suitable rare-earth-doped solids in which persistent spectral holes can be burned on weakly allowed electronic transitions. These systems are of interest as frequency references for the stabilization of laser frequencies. In all experiments so far, spectral holes are burned and read out individually. Here we present a demonstration of simultaneous burning and readout of sets of spectral holes, containing up to 1024 individual spectral holes, by a comb of laser frequencies. The simultaneous readout of such a set leads to an effective compound signal that has a higher signal-to-noise ratio. Here, an improvement by a factor of 20 was obtained for a set of 512 spectral holes. We use the method to stabilize the frequency of a laser and characterize its stability.