Carrier-envelope offset frequency dynamics of a modelocked Ti:sapphire laser

Summary form only given. With pulse durations in the two-optical-cycle range, the typical assumption of a slowly-varying envelope in optics is expected to fail. Experimentally, the breakdown of this assumption manifests itself in a dependence of the conversion efficiency of nonlinear optical processes on the relative phase between carrier and envelope of a short pulse. Recently, the discussion on a sub-cycle-sensitivity in nonlinear optics has been stimulated by a proposal of several methods to measure and control the carrier-envelope offset (CEO). Meanwhile measurement of the CEO frequency has been successfully used for precision metrology, providing a direct phase-coherent link between microwave and optical frequency standards. Still, a CEO phase dependence in nonlinear optics has not yet been directly demonstrated. We measured and stabilized the CEO-frequency of a Ti:sapphire laser oscillator, Our set-up employs continuum generation in a microstructure fiber, frequency-doubling of the long-wavelength part of the spectrum and subsequent heterodyning with the short-wavelength part. This relatively simple set-up allows isolating the CEO-frequency with a signal-to-noise ratio of more than 40 dB in a 300-kHz bandwidth.