A term applied to a pulsed laser, meaning that the laser emission lasts as long as the pumping process is sufficient to sustain lasing conditions. Typical pulse durations are in the µs-ms range, depending on the pumping source. When the operation mode of a pulsed laser is not specified as mode-locked, Q-switched, or anything else, it must be considered as free-running.
Source:
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2244 (https://doi.org/10.1351/pac199668122223)