Suppression of Optical Feedback in Laser Diodes Using Multilayered Broad-band Ultra-low Reflective Facets-coating

The multilayered anti-reflection coating (ARC) has been designed and implemented on the facets of edge-emitting laser diode in order to achieve ultra-low reflectivity over a broad wavelength range for suppression of optical feedback in the laser cavity. The design of the multilayer ARC has been obtained by a self-developed program based on genetic algorithm (GA) to achieve low-reflectivity of the order of 0.1 % over a spectral width of 50 nm around the central lasing wavelength of 818 nm and successfully implemented on the laser-diode facets. The effects of facets coating on the optical power emission and the spectral response of the lasers have been investigated. It is demonstrated that the simple design of multilayered ARC obtained using a self-developed GA can successfully reduce the optical feedback from the cavity and prevent the lasing action from the structure, which can be very useful for the fabrication of superluminescent Light Emitting Diodes (SLEDs).