A mirror that reflects most of the intracavity light back and transmits a set fraction as output. Low-gain lasers use output couplers transmitting 1 to 10 percent; high-gain systems can use 50 percent or more. Picking the right transmission balances threshold against extraction: too little and the light stays trapped, too much and the laser barely reaches threshold. The other end is the high reflector, usually above 99.9 percent.
Try the 5 percent output coupler instead of the 10, we're barely over threshold and the gain is lower than we modeled.
Also heard as
- OC
- partial reflector
- output mirror
Related terms
Resonator
The arrangement of mirrors that sends light back and forth through the gain medium to build up laser oscillation.
Lasing threshold
The pump level at which gain exactly balances resonator losses and laser output begins.
Slope efficiency
The rate at which laser output power rises per unit of extra pump power above threshold.
Fiber Bragg grating
A periodic index pattern written into a fiber core that reflects a narrow band of wavelengths and passes the rest.