Micromachining of optical structures with focused ion beams

Abstract

For the first generation of lightwave devices, semiconductor lasers and detectors have been used as discrete elements. As the technology continues to evolve, integration of light sources with electronics or other optical elements will be necessary. However, an efficient and reliable method for generating laser facets and other optical elements internal to the integrated system must first be developed. Three dimensional features have been milled into optical materials by scanning a submicron focused gallium ion beam. Different shapes are obtained using computer controlled beam placement and dwell time during sputtering. We have used this technique to create micron-sized facets and reflectors in the active areas of semiconductor lasers. Light output and quantum efficiency measurements indicate that these features are of sufficient quality to fabricate monolithic integrated optical devices. Some of the applications currently being investigated are laser–detector pairs, coupled cavity lasers, lasers with integral lenses, distributed feedback lasers, confocal cavities, and laser cavity length tuning.