Chirped mirrors with low dispersion ripple

Abstract

We demonstrate a chirped dielectric multilayer mirror (CM) with controlled reflectivity and dispersion in the wavelength range 760-840 nm. It exhibits a reflectivity of >99.9% and a mean group delay dispersion (GDD) of about -30 fs² with a theoretical GDD ripple of less than 0.5 fs² in the working spectral range. Deviations of the measured GDD from the calculated one are restricted to less than ±3 fs², limited by our measurement system. Simulations reveal that a dispersive delay line composed of 120 bounces off these mirrors introduces negligible distortion to a femtosecond pulse and largely preserves its contrast. The mirrors constitute an ideal tool for precision intracavity or extracavity dispersion control in the range of several thousand fs², particularly if pulses with high contrast are to be generated. ©2007 Optical Society of America.