Improvement of SLD efficiency by focussed ion beam post-fabrication processing

Superluminescent Diodes are high power semiconductor optical sources with relatively broad spectral linewidth used for a variety of applications. The basic, crucial device feature needed to achieve high-power superluminescent operation is low facet reflectivity to prevent lasing and optical gain saturation. Theoretical calculations show that by appropriately designing the device length and output facet reflectivity a significant increase in optical output power and wall-plug efficiency can be obtained. This paper presents theoretical and preliminary experimental results indicating that it is possible to further improve the operational characteristics of superluminescent diodes and achieve high optical output power with high conversion efficiency. The control of the facet reflectivity and the overall device optical geometry are obtained by using Focused Ion Beam post-fabrication processing. Results obtained from the characterisation of superluminescent diodes before and after facet reflectivity alteration achieved by creating patterns on the subwavelength scale will be discussed.