We show that, for a cw passively mode-locked picosecond Ti:sapphire/DDI laser, the first autocorrelation trace with negligible cw background occurs at a delay time of 20 mu;s, or 1600 round trips from the first relaxationoscillation peak. The trace suggests that the pulse consists of a primary pulse as short as 4.4 ps and of small secondary pulses that form a much wider pedestal of the trace, each containing ≈50% of the photon energy. Nearly transform-limited ≈5-ps-wide Gaussian pulses were observed at a delay time of 40 mu;s. After 45 mu;s, the optical spectrum broadened considerably, and the time–bandwidth product increased to 4 in the steady state (after 60 µs).
© 1995 Optical Society of America
Nen-Wen Pu, Jia-Min Shieh, Yinchieh Lai, and Ci-Ling Pan, "Starting dynamics of a cw passively mode-locked picosecond Ti:sapphire/DDI laser," Opt. Lett. 20, 163-165 (1995)