A superradiance light source (also known as an ASE light source) is a superradiance-based broadband light source (white light source). (It is often mistakenly called a superluminescent light source, which is based on a different phenomenon called superfluorescence.) Generally, a superluminescent light source contains a laser gain medium that is excited to radiate light and then amplified to emit light.
Superradiant light sources have very low temporal coherence due to their large radiation bandwidth (compared to lasers). This greatly reduces the likelihood of spotting, which is often seen in laser beams. However, due to its high spatial coherence, the output light of a superradiant light source is well focused (similar to a laser beam), and therefore much more intense than that obtained from an incandescent lamp. Therefore, this light source is very suitable for optical coherence tomography (Optical Coherence Tomography, OCT), device characterization (in fiber optic communications), gyroscopes and fiber optic sensors. See the entry Superluminescent Diodes for more detailed applications.
The most important kind of superluminescent light sources are superluminescent diodes SLDs and fiber amplifiers. Fiber-based light sources have higher output power, while SLDs are smaller and less expensive. The radiation bandwidth of both is at least several nanometers and tens of nanometers, and sometimes even greater than 100 nanometers.
As with all high-gain ASE sources, careful suppression of optical feedback (eg, reflections from fiber ports) is required, so it can produce parasitic lasing effects. For devices using optical fibers, Rayleigh scattering inside the optical fiber can have an impact on the final performance index.