Ultrashort Pulse Compression for Mode-Locked Ti:Sapphire Laser by Using a Tapered Fiber and Grating Pair

摘要

Extracavity pulse compression for pulses from an 82 MHz mode-locked Ti:sapphire laser is demonstrated by utilizing a tapered fiber of 1 μm in diameter and 10 mm in length. Group velocity dispersion of the tapered fiber is calculated, which shows two zero dispersion wavelengths locating at 545 and 1250 nm, respectively. The nonlinear coefficient y of the tapered fiber is estimated to be 733 (W~(-1) km~(-1)) at 880 nm wavelength. With 80 fs input pulses at 880 nm center wavelength, the optical bandwidth is broadened beyond 22THz by the tapered fiber. After dispersion compensation by a grating pair with 1.45cm separation, 26fs output pulses are obtained. One-third pulse compression ratio has been experimentally demonstrated in this work for center wavelengths ranging from 720 to 880 nm.