NOEMS Based Slotted Photonic Crystal Cavity for the Sensing of Force

Abstract

In the paper, a two dimensional slotted photonic crystal cavity (2D-SPCC) has been designed and optimized for the application of sensing. The optimized 2D-SPCC has been incorporated in a silicon cantilever to form a nano-opto-electro-mechanical system (NOEMS) for sensing the physical parameters like - force, displacement and strain. An applied force at the cantilever-tip generates strain which results in deformation of the SPCC parameters like slot-width. This structural change in the 2D-SPCC changes the optical behavior of the device, which can be sensed, and thus operate as a physical sensor. Resonant wavelengths of the SPCC are determined for different length and breadth of the cantilever. The results show a linear dependence of the resonant wavelength with the change in the physical parameters. The 2D-SPCC has a high quality factor and sensitivity of $\sim\!9 \, \times\, 10^6$ and 4.2 nm $\mu$ N respectively, due to which the minimum detectable force, displacement and strain for the proposed design are found as 0.0202 $\mu$ N, 0.090 707 $\mu$ m and 0.019 979 respectively for a cantilever of length 40 $\mu$ m and breadth 20 $\mu$ m. Hence, the proposed NOEMS sensor is expected to be highly relevant for different industrial applications.