Broadband continuum generation in mode-locked lasers with phase-matched output couplers.

The concept of intracavity phase matching is proposed and demonstrated both theoretically and experimentally with a broadband phase-matched dielectric output coupler for linear-cavity few-cycle Ti:sapphire oscillators. The spectrum in the matched wavelength range is enhanced by >10  dB while maintaining good beam quality via resonantly enhanced continuum generation. The enhanced spectral components can be continuously tuned by varying the intracavity dispersion. Because dielectric coatings offer flexible design capabilities, this approach is applicable to various lasers with different gain media to obtain custom-tailored spectra, which have the potential to benefit several applications, such as shorter pulse generation, seeding of ytterbium lasers for pumping optical parametric amplifiers, and direct f-2f detection of the carrier-envelope phase.