Focused ion beam-based fabrication of nanostructured photonic devices

This paper presents results for focused ion beam (FIB) processing of two photonic devices: 1) a GaN laser with a fourth-order grating for vertical emission, and 2) a two-dimensional (2-D) photonic crystal (PhC) structure. For the GaN laser, both L-I and I-V results are shown before and after etching, and vertical emitted power as a function of the distance along grating is shown. A finite element (FE)-based electromagnetic model is developed to support the measured results and is used to predict the optimum grating depth. For the 2-D photonic crystal, direct FIB etching is used to create a PhC in a standard InP waveguide structure. Measured and modeled transmission results are compared, and there is good agreement for band edge position. A detailed study of hole shape is presented, and this leads to the development of a multistage etching procedure involving both reactive ion etching and inductively coupled plasma etching. This results in a much improved hole shape.