Femtosecond Laser Pulses Combine

A team at JILA in Boulder, Colo., has taken the first steps toward enabling researchers to tailor laser pulses to their particular ultrafast science experiments. In the Aug. 17 issue of Science, the group described how it combined the femtosecond output of a 760- and an 810-nm Ti:sapphire laser to yield a single pulse of light.

The researchers first synchronized the repetition rate of the two 100-MHz lasers, using either a microwave clock or a reference laser to ensure that their pulses emerged simultaneously. They also synchronized the carrier phase within the pulses, using an acousto-optic modulator to lock the offset frequency of the combs to a mean value of 0 Hz.