Fig. 4: Typical designs and properties of SLDs.
From: Low-coherence semiconductor light sources: devices and applications

a The different designs of SLDs based on typical edge-emitting lasers with ridge-waveguide structures. In many cases, a combination of these techniques is used to achieve the required feedback suppression. b A comparison of their optical power versus current characteristics. c A comparison between the typical optical spectra from a laser diode, a superluminescent diode (SLD) and a light-emitting diode (LED).