Mirror design to facilitate fabrication of a ultra-short pulse Ti:sapphire oscillator

Summary form only given. In these several years, the pulse duration of a mode-locked Ti:sapphire oscillator has been reduced. It is a chirped mirror that contributes very much to the shortening, because a chirped mirror can compensate the high order dispersions with wide spectral range (/spl Delta//spl lambda/>300 nm) in the cavity of the oscillator. For recent sub-6 fs pulse generation from a mode-locked oscillator, a double-chirped mirror was used. A double-chirped mirror has very thin (/spl sim/10 nm) layers. It is difficult to fabricate it, because an ultimately precise control of thickness of the layers is required. In this paper we design a mirror for dispersion compensation of sub-6 fs Ti:sapphire oscillator, which has the layers with optical thickness of more than 100 nm to eliminate the difficulty of the fabrication.