NANO-DISP · THEORETICAL AND EXPERIMENTAL INVESTIGATION OF SYNCHRONOUS SILICON NANOWIRE WAVEGUIDE DISPLACEMENT SENSORS

Recently, an approach using physical contact of suspended nanowire silicon waveguides for optical switching is presented using silicon photonics technology aiming telecommunication field. The demonstrated switch changed its state by in-plane displacement of a movable elliptical waveguide generated by a NEMS actuator. The technique provides sensitivity even to submicron distance/displacement levels and is applicable to various wavelengths. Later, effects of the waveguide tip geometry and relative positioning of the input and output waveguides on the optical characteristics of the waveguide connections are investigated both theoretically and experimentally. Although these efforts were towards realizing optical switches and connections, same approach can well be employed as an optical distance/displacement sensor in demanding silicon photonics devices, and in general, in acoustical, flow, mechanical displacement sensing as an embedded tool. The objective of this proposal is to investigate synchronous silicon nanowire waveguide displacement sensors both theoretically and experimentally. Furthermore, the measurement range and sensitivity can be engineered as the application changes by customizing the waveguide tip geometries. The technique is also extendable to post-micron-level displacement ranges and various wavelengths by proper selection of the waveguide and buffer materials, and appropriate light sources and photodetectors. In the proposed approach, measurement of out-of-plane distances/displacements is also possible by use of optical waveguides. The proposed approach is expected, for the first time, to yield guidelines for a standard and customizable optical measurement technique for embedded synchronous submicron distance/displacement sensors covering slow to very high frequencies.