Optical phase-noise dynamics of Titanium:sapphire optical frequency combs
Qudsia Quraishi, Scott A. Diddams, Leo W. Hollberg
Stabilized optical frequency combs (OFC) can have remarkable levels of coherence across their broad spectral bandwidth. We study the scaling of the optical noise across hundreds of nanometers of optical spectra. We measure the residual phase noise between two OFC's (having offset frequencies f01 and f02 ) referenced to a common cavity-stabilized narrow linewidth CW laser. Their relative offset frequency δf0 = f02 - f01 , which appears across their entire spectrally overlapped region, provides a convenient measure of the phase noise. By comparing δf0 at different spectral regions, we demonstrate that the observed scaling of the residual phase noise is in very good agreement with the noise predicted from the standard frequency comb equation.