Amplitude and phase noise sensitivity of modelocked Ti:sapphire lasers in terms of a complex noise transfer function

The amplitude and envelope phase noise of a modelocked laser are shown to depend directly on the pump laser amplitude stability. We characterize the sensitivity of this process by a noise transfer function which represents the complex amplitude-to-amplitude modulation (AM-AM) and amplitude-to-phase modulation (AM-PM) conversion gain of the pump-induced amplitude and phase noise, respectively. We find that a linearized laser model extrapolated from relaxation oscillation theory, combined with a thermal model, adequately describe the principal features of the response from <1 Hz to 10 MHz.