The time between the two points where pulse intensity is half its peak. Q-switched lasers give nanoseconds and are measured with fast photodiodes and oscilloscopes; mode-locked lasers give picoseconds and femtoseconds, which no electronics can resolve, so autocorrelators or FROG devices are used. Pulse duration and energy together determine peak power and the nature of laser-material interaction.
Pulse duration out of the compressor is 140 fs, we were at 95 last week, so somebody touched the grating.
Also heard as
- pulse width
- pulse length
- tau
Related terms
Peak power
The highest instantaneous power reached during a laser pulse, roughly pulse energy divided by pulse duration.
Autocorrelator
An instrument that measures ultrashort pulse duration by overlapping a pulse with a delayed copy of itself.
Transform-limited
Describes a pulse that is as short as its spectral bandwidth allows, with no leftover chirp.
Femto
Clipped form of femtosecond, for lasers and pulses lasting from a few to a few hundred quadrillionths of a second.
Chirp
A change in instantaneous frequency across a pulse, so its colors arrive spread out in time.