Analysis and filtering of phase noise in an optical frequency comb at the quantum limit to improve timing...

It is shown that the sensitivity of a highly sensitive homodyne timing measurement scheme with femtosecond (fs) lasers [Phys. Rev. Lett.101, 123601 (2008).] is limited by carrier-envelope-phase (CEO) noise. We describe the use of a broadband passive cavity to analyze the phase noise of a Ti:Sapphire oscillator relative to the standard quantum limit. This cavity also filters the lowest levels of classical noise at sidebands above 100 kHz detection frequency. Leading to quantum-limited CEO-phase noise at millisecond time scales, it can improve the sensitivity of the homodyne pulse timing measurement by 10 dB.