Title: free-running laser
Long Title: IUPAC Gold Book - free-running laser
DOI: 10.1351/goldbook.F02521
Status: current

Definition
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 \(\pu{\upmu s}\)-\(\pu{ms}\) 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.

Related Terms
- laser: https://goldbook.iupac.org//terms/view/L03459
- lasing: https://goldbook.iupac.org//terms/view/L03479
- mode: https://goldbook.iupac.org//terms/view/M03958

Source
- PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2244 (https://doi.org/10.1351/pac199668122223)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/F02521/html
- json: https://goldbook.iupac.org/terms/view/F02521/json
- xml: https://goldbook.iupac.org/terms/view/F02521/xml

Citation: Citation: 'free-running laser' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.F02521
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Accessed: 2026-05-09T13:32:13+00:00