Laser stabilization at 1536 nm using regenerative spectral hole burning

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 ${}^4{I}_{15/2}{\mathrm{}\left(1\right)\mathrm{}}^4{I}_{13/2}\mathrm{}\left(1\right)\mathrm{}$ optical absorption of an ${\mathrm{Er}}^{3+}:{\mathrm{Y}}_2{\mathrm{SiO}}_5$ 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.