Feedback suppression in 405 nm superluminescent diodes via engineered scattering

Abstract

Superluminescent diodes (SLDs) are promising devices for applications in which low coherence, high efficiency, small footprint and good optoelectronic integration are required. Blue emitting SLDs with good performances and easy fabrication process are sought for next generation solid state lighting devices, micro-projectors and displays. These devices are laser diodes (LDs) in which the optical feedback is inhibited and lasing action avoided. Conventional fabrication processes minimize optical feedback by ad hoc designs, e.g. anti-reflection coating, tilted waveguide or absorber sections, requiring specific fabrication steps. In this work, we propose and demonstrate the introduction of scattering defects in the device’s waveguide as a method for feedback inhibition. By performing pulsed laser ablation on a commercial 405 nm GaN LD we demonstrate a SLD, featuring a maximum output power of 1.8 mW and a spectral width of 5.9 nm.