Cross-locking dynamics in a two-color mode-locked Ti:sapphire laser.

We investigate the nonlinear interactions between pulses of two different wavelengths within a single cross-mode-locked femtosecond Ti:sapphire laser. We show that the nonlinear interaction caused by self-focusing can correct for a difference in cavity lengths of as much as +/-3 microm, corresponding to 20% of the pulse width on each round trip. Further, we show that the concept of mean group delay can be extended to a pair of pulses with disparate spectra and spatial distribution in a nonlinear regenerative system.

Timing-jitter stabilization of a colliding-pulse mode-locked laser by active control of the cavity length.

Colliding-pulse mode-locked lasers are an excellent source of ultrashort pulses but exhibit timing jitter that can seriously degrade the temporal resolution in experiments that require synchronization to an external source. We describe a method that synchronizes the colliding-pulse mode-locked laser to a high-stability external oscillator by actively controlling the cavity length of the laser and reduces the absolute timing jitter from ~25 ps rms to only 1.7 ps over the 1-kHz bandwidth, which contains most of the laser phase noise.

Picosecond pump and probe spectroscopy utilizing freely propagating terahertz radiation.

We demonstrate the feasibility of scaling up a terahertz-pulse generation scheme for use with a 10-Hz amplified femtosecond laser system. Visible pulsed excitation combined with a far-infrared probe should prove to be a powerful picosecond time-resolved technique.