Amplified Spontaneous Emission, light that begins as spontaneous emission inside a pumped gain medium and is then amplified on its way out. It is broadband, incoherent in time and present in every amplifier, where it adds noise and steals stored energy from the signal. In high-gain fiber amplifiers with weak or missing seed, ASE can grow into parasitic lasing that destroys components.
Spectrum shows a hump of ASE 30 dB down around 1035, bump the seed power before we turn up the booster.
Never pump a high-gain fiber amplifier with the seed off: with nothing to amplify, the ASE builds up and can self-pulse hard enough to damage the fiber end.
Also heard as
- amplified spontaneous emission
Related terms
Stimulated emission
Emission of a photon by an excited atom, triggered by an incoming photon and identical to it in color, phase and direction.
EDFA
Erbium-Doped Fiber Amplifier: the optical amplifier that boosts signals near 1550 nm without converting them to electronics.
Gain saturation
The drop in an amplifier's gain as the signal grows strong enough to deplete the stored inversion.
Seed
The low-power laser whose output is amplified in a MOPA or amplifier chain, setting its timing and spectrum.