Superluminescent diodes(SLD or SLED) are broadband semiconductor components that operate with Amplified Spontaneous Emission( ASE). The effect of amplified spontaneous emission occurs wherever light signals are amplified.
Superluminescent diodes are similar in structure to laser diodes. They are made of semiconductor materials with indium or gallium compounds. The broadband capability is based on the fact that SLDs do not have a laser cavity in which optical feedback takes place. SLDs generate light by spontaneous emission at a pn semiconductor junction and amplify it in an optical waveguide.
SLDs emit at optical window wavelengths at 800 nm, 1,300 nm and 1,550 nm. In addition, there are superluminescent diodes for other wavelengths and for visible light. The bandwidth of SLDs is between 10 nm and 100 nm.