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Pulses shorter than two optical cycles at 90 MHz repetition rate and 200 mW average power are demonstrated using a Kerr-lens modelocked Ti:sapphire laser with improved dispersion compensation. The pulse formation is explained by dispersion-managed soliton generation. An initial application of this source to ultra high resolution optical coherence tomography is demonstrated.

We demonstrate Ti:sapphire laser pulses of unprecedented spectral width, covering an optical octave without external continuum generation. The pulse spectrum spans more than 170 THz and supports bandwidth-limited two-cycle pulses. Assuming a sech2 pulse, the autocorrelation corresponds to a 4.8-fs pulse duration. The average power is 300 mW at a repetition rate of 100 MHz. The key features of the cavity are: dispersion compensation with broadband double-chirped mirrors combined with a prism pair, a broadband semiconductor saturable absorber mirror (SESAM) to assist Kerr-lens modelocking, and an output coupling mirror specifically designed to broaden the pulse spectrum.