Feature

High-Repetition Rate Broadly Tunable Femtosecond Sources

C.L. Tang, R. J. Ellingson and P.E. Powers

High-repetition rate, broadly tunable femtosecond sources are particularly important for the study of ultrafast processes because high repetition rates yield higher signal-tonoise ratios in such experiments, and because broad tunability allows a greater variety of materials and processes to be studied. Since the first demonstration of the broadly tunable femtosecond optical parametric oscillator (fsec OPO) several years ago, dramatic advances in the development of such sources have occurred. Initially, only the Rh6G fsec dye laser was available as a pump source. This made the operation of the fsec OPO very difficult and the output power relatively low. With the development of the relatively high-power modelocked Ti:sapphire lasers, the situation has changed fundamentally. Using the fs Ti:sapphire laser as a pump, high repetition rate fsec OPOs producing hundreds of milliwatts broadly tunable from 900 nm to over 3.5 μm have been demonstrated. This development paved the way for the introduction of commercial fsec OPOs.