Hybrid Diamond/Silicon Suspended Integrated Photonic Platform using SF6 Isotropic Etching

A hybrid diamond/silicon air-clad ridge waveguide platform is demonstrated. The air-clad structure coupled with the wide transmission window of diamond can allow for the use of this architecture over a large wavelength range, especially for the longer infrared wavelengths. In order to provide vertical confinement, the silicon substrate was isotropically etched using SF6 plasma to create undercut diamond films. An in-depth analysis of the etch characteristics of this process was performed to highlight its potential to replace wet isotropic etching or XeF2 isotropic vapour phase etching techniques. The performance of the waveguide at 1550 nm was measured, and yielded an average loss of 4.67 +/- 0.47 dB/mm.