Negative dispersion mirrors for dispersion control in femtosecond lasers: chirped dielectric mirrors and multi-cavity Gires-Tournois interferometers

Chirped dielectric laser mirrors have been known for years as useful device s for broadband feedback and dispersion control in femtosecond pulse lasers . First we present a novel design technique referred to as frequency domain synthesis of chirped mirrors. These mirrors exhibit high reflectivity and nearly constant group delay over 150 THz supporting generation of sub-5-fs pulses in the visible. Afterwards, multi-cavity thin-film Gires-Tournois in terferometers are introduced for the first time as an alternative approach to realize "negative dispersion mirrors". These novel dielectric high refle ctors exhibit reflectivities R > 99.97% and a negative group delay dispersi on of -50 +/- 1 fs(2) over a bandwidth of 56 THz. Dispersive propel ties or iginate from coupled resonances in multiple lambda/2 cavities embedded in t he layer structure. The general structure and performance of multicavity Gi res-Tournois interferometers are compared to that of chirped dielectic mirr ors and their distinct applications are discussed.