Calculation of the quantum-limited comb lineshape for a mode-locked Ti:sapphire laser

Abstract

We have calculated the spontaneous emission limited lineshape of the comb lines from a mode-locked Ti:sapphire laser using experimentally-derived parameters for the linear response. The lineshape has contributions from the dynamic response of the laser. Our results allow us to determine the fundamental limitation due to spontaneous emission on the uncertainty of frequency measurements using femtosecond frequency combs, when the effects of feedback and the frequency measurement equipment are properly taken into account.