The input that creates population inversion: light from laser diodes or flashlamps, an electric discharge in gas lasers, or drive current in semiconductor lasers. Pump wavelength is matched to an absorption band, such as 808 nm for Nd:YAG or 915 and 976 nm for Yb fiber. The energy difference between pump and laser photons, the quantum defect, ends up as heat, which drives most thermal problems in high-power lasers.
Pump diodes are running two degrees warm, so absorption is off the 976 peak and output's down eight percent.
Yb fiber pumped at 976 nm absorbs in a narrow peak, so pump diodes need wavelength-stabilized chips or tight temperature control, while 915 nm pumping is far more forgiving.
Also heard as
- pumping
- pump light
Related terms
Gain medium
The material inside a laser or amplifier that amplifies light once it is pumped: a crystal, glass, gas, semiconductor or doped fiber.
Population inversion
The condition where more atoms occupy the upper laser level than the lower one, which a medium needs to give gain.
Laser diode
A semiconductor laser driven by electric current, used as a light source in its own right and to pump other lasers.
Slope efficiency
The rate at which laser output power rises per unit of extra pump power above threshold.
Pump combiner
A fused fiber component that merges the outputs of many pump diodes into the inner cladding of a double-clad fiber.