Abstract

A Ti:Al₂O₃ amplifier has a very wide (200-nm) gain bandwidth and thus excellent potential for amplifying and tuning of femtosecond laser pulses. We have used a Ti:Al₂O₃ injection seeded laser pumped by a 2-mJ copper vapor laser to amplify the output of a synchronously pumped dye laser. To pump the dye laser a mode-locked Nd:YAG laser is pulse compressed to 5 ps using a fiber and grating pair and frequency doubled. A single pulse from the 82-MHz 400-fs pulse train of the dye laser is selected using an acoustooptic modulator. This pulse is mode matched and coupled with a beam splitter into the Ti: Al₂O₃ laser. A wavelength-independent Faraday isolator is placed in the beam path to protect the acoustooptic modulator from the high-power Ti: Al₂O₃ laser output. The injection seeded laser¹ employs an 8% output coupler. With only 0.1 pJ of incident seed energy at 790 nm, the Ti: Al₂O₃ laser is mode-locked. The output is a 100-ns pulse train with pulses spaced by 2.1 ns, which is determined by the Ti: Al₂O₃ cavity length. A single pulse contains 1 µJ and has a pulse width of 1.5 ps. These pulses have been recompressed with a grating pair to 300-fs pulse widths.

© 1988 Optical Society of America