The point at which round-trip gain equals the total loss from mirrors, scattering and absorption. Below it the output is weak spontaneous emission; above it output power climbs roughly linearly with pump, and the slope of that line is the slope efficiency. Threshold is read off a plot of output against pump power, and a rising threshold over time points to dirty or damaged optics.
Threshold moved from 1.2 to 1.8 amps since last month, somebody check the output coupler for a burn.
Also heard as
- threshold
- threshold current
- threshold pump power
Related terms
Slope efficiency
The rate at which laser output power rises per unit of extra pump power above threshold.
Output coupler
The partially transmitting resonator mirror through which the laser beam leaves the cavity.
Kink
A sudden bend or step in a laser diode's power-versus-current curve, usually a sign of mode switching.
Stimulated emission
Emission of a photon by an excited atom, triggered by an incoming photon and identical to it in color, phase and direction.