A high-power GaAlAs superluminescent diode with an antireflective window structure

A novel high-power GaAlAs superluminescent diode (SLD) structure that introduces an antireflective (AR) window region into the rear side of the SLD is proposed. The light beam which travels backward is emitted from the edge of the active layer and diverges in the window region. Then the beam is reflected at the AR-coated rear facet only by a small percentage, a fraction of which couples into the active layer. Thus, this window structure gives a reduction of the reflectivity at the interface between the active layer and the window region so that lasing oscillation is successfully suppressed. An SLD operation of output power as high as 50 mW is obtained with a stable fundamental spatial mode. The spectral bandwidth at half maximum is about 15 nm over a wide output power range