Two or more mirrors, or a fiber with gratings or a closed ring, that return light through the gain medium many times. The mirror curvatures and spacing decide whether the resonator is stable, which modes it supports and how large the beam is inside. A high reflector at one end and a partially transmitting output coupler at the other is the simplest linear layout.
Resonator's right on the edge of stability at full pump, so the thermal lens flips it and the mode falls apart.
Also heard as
- cavity
- optical cavity
- laser cavity
Related terms
Output coupler
The partially transmitting resonator mirror through which the laser beam leaves the cavity.
Longitudinal mode
One of the discrete frequencies at which a standing wave fits a whole number of half-wavelengths into the resonator.
Thermal lensing
The lens effect a heated gain medium or optic creates as its center gets hotter than its edges.
Free spectral range
The frequency spacing between neighboring resonances of a laser cavity, etalon or interferometer.
TEM00
The fundamental transverse mode of a laser: a single round spot with a Gaussian intensity profile.