Ultra-stable Frequency Reference Based on Spectral Hole Burning

Highly stable, ultra-narrow linewidth frequency references are required for current and next generation timing systems. Timing systems with improved accuracy from primary clocks to fieldable references all require laser oscillators with improved inherent stability (time scales shorter than ~ 1 second). This proposal describes a novel frequency reference based on spectral hole burning in rare-earth doped crystals that overcomes many limitations of conventional mechanical reference cavities, thus providing a more environmentally insensitive, ultra-narrow linewidth laser oscillator. Physical Sciences Inc. (PSI), in collaboration with Montana State University (MSU), proposes to develop a fieldable ultra-narrow linewidth reference oscillator based on the technique of spectral hole burning in rare-earth doped crystals with fractional frequency stability better than one part in 10^15 over a one second timescale and sensitivity to vibrations better than one part in 10^11 per g of acceleration.