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

The sensitivity of homodyne timing measurements with femtosecond lasers is only limited by the amplitude and phase noise. We describe a novel method to analyze the phase noise of a Ti:Sapph oscillator relative to the standard quantum limit. The broadband passive cavity used to this aim also filters lowest levels of classical noise at sidebands above 100kHz detection frequency. Leading to quantum limited carrier-envelope-phase noise at $\mu$s-timescales, it can improve the sensitivity of a highly sensitive, homodyne timing jitter measurement by 2 orders of magnitude.