N. M. Strickland

Programmable frequency reference for subkilohertz laser stabilization by use of persistent spectral hole burning.

We report what is believed to be the first demonstration of laser frequency stabilization directly to persistent spectral holes in a solid-state material. The frequency reference material was deuterated CaF(2): Tm(3+) prepared with 25-MHz-wide persistent spectral holes on the H(6)(3)?H(4)(3) transition at 798 nm. The beat frequency between two lasers that were independently locked to persistent spectral holes in separate crystal samples showed typical root Allan variances of 780+/-120Hz for 20-50-ms integration times.

Semiconductor lasers stabilized to spectral holes in rare-earth crystals

Single-frequency diode lasers have been frequency stabilized to 200 Hz at 1.5 microns and to 20 Hz at 793 nm with 10-100 ms integration times using narrow spectral holes in the absorption lines of Er3+ and Tm3+ doped cryogenic crystals. The narrow spectral holes are used as frequency references, and this laser performance was obtained without requiring vibrational isolation of either the laser or frequency reference. Kilohertz frequency stability for 100 s integration times is provided by these techniques, and that performance should be improved to the Hertz level and should be extended to longer integration times with further development. Miniaturized external cavity diode lasers and 5 mm-sized reference crystals will provide compact portable packages with a closed cycle cryocooler. The achieved frequency stabilization provides lasers that are ideal for interferometry, high-resolution spectroscopy such as photon echoes, real time optical signal processing based on spectral holography, and other applications requiring ultranarrow-band light sources or coherent detection.

Compact laser frequency stabilization at 1.5 /spl mu/m using spectral hole burning

Summary form only given. Laser frequency stabilization to 200 Hz on a 5 ms time scale and to 1 kHz over 30 minutes has been demonstrated using persistent and transient spectral holes in inhomogeneously broadened resonances of Er/sup 3+/,D/sup -/:CaF/sub 2/, Er/sup 3+/:Y/sub 2/SiO/sub 5/, and Er/sup 3+/:KTiOPO/sub 4/ at cryogenic temperatures. Persistent spectral holes with lifetimes of weeks or longer provide a programmable and transportable secondary frequency reference, and kilohertz wide transient spectral holes provide excellent references at millisecond time scales appropriate for spectroscopy and coherent transient signal processing devices. This locking technique has significant applications to devices beyond the field of spectral hole burning.

Programmable frequency reference for laser stabilization using persistent spectral hole burning

Summary form only given. The first known demonstration of laser frequency stabilization using a solid-state persistent spectral hole burning material as the frequency reference is reported. Unlike gas phase transitions or Fabry-Perot resonances, spectral holes for frequency references can be prepared at any frequency within a broad inhomogeneous absorption profile (15 GHz in the material demonstrated here). Several lasers may be stabilized to multiple spectral holes, either in the same or separate absorption bands, with arbitrary frequency separations.