Laser frequency stabilization giving a 500-Hz Allan deviation for a 2-ms integration time with drift reduced to 7 kHz/min over several minutes was achieved at 1536 nm in the optical communication band. A continuously regenerated spectral hole in the inhomogeneously broadened 4I15/2(1)!4I13/2(1) optical absorption of an Er31:Y2SiO5 crystal was used as the short-term frequency reference, while a variation on the locking technique allowed simultaneous use of the inhomogeneously broadened absorption line as a long-term reference. The reported frequency stability was achieved without vibration isolation. Spectral hole burning frequency stabilization provides ideal laser sources for high-resolution spectroscopy, real-time optical signal processing, and a range of applications requiring ultra-narrow-band light sources or coherent detection; the time scale for stability and the compatibility with spectral hole burning devices make this technique complementary to other frequency references for laser stabilization.
Sellin, P.B., Strickland, N.M., Böttger, T., Carlsten, J.L., Cone, R.L. Laser stabilization at 1536 nm using regenerative spectral hole burning. (2001) Physical Review B - Condensed Matter and Materials Physics, 63 (15), art. no. 155111. https://doi.org/10.1103/PhysRevB.63.155111