Nanomechano-Grating-Coupler-Modulator And Integrated Optical Microphone

Publisher Website
Google Scholar
Abstract
We demonstrated both a novel integrated optical modulator and a microphone. They are based on an input grating coupler on a planar waveguide. Their working principle is as follows: the incoupled power is modulated by varying the width d of the small air gap between an "effective-refractive-index-shifting element E", i.e., a nonabsorbing dielectric plate, and the waveguide in the coupler region. Since d < A, where 1. is the wavelength, the evanescent field of the guided mode penetrates through the air gap into the element E. Because of this interaction, the Ad variations induce changes in the effective refractive index N of the guided mode, and consequently in the incoupling efficiency. Sufficiently high modulations can be achieved with gap width variations Ad of only a few nanometers which, in turn, are effected by external forces, namely by a piezoelectrically generated force in the case of the modulator, and by sound pressure in the case of the microphone. In our experiments, we used thin monomode Si0,-TiO2 waveguides with embossed surface relief gratings of 1200 or 2442 lines/mm. The effettive-refractive-index-shifting element E was a glass plate. Modulation frequencies of up to 480 kHz were reached.© (1989) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This publication has 0 references indexed in Scilit: