Mechanical tuning of two-dimensional photonic crystal cavity by micro Electro mechanical flexures

A nano-displacement sensing method for micro-opto-electro-mechanical-systems (MOEMS) is proposed. The method is based on a square attice photonic crystal (PC) made of dielectric silicon posts, mounted on a micro mechanical flexure. The flexure is fixed at one end and is free to ove at the other, to enable elastic deformations that, by being transferred to the photonic crystal array, modify its periodicity and the pertinent ransmission characteristics. A missing-post defect is deliberately introduced in the photonic crystal, opening a narrow pass band within the band ap. The pass band wavelength is sensitive to dilatation of the micro mechanical flexure. The flexure Poisson ratio (PR) can be designed according o specific requirements to gain desired sensitivity. Simulations show high sensitivity of 12.3 nm band pass shift for every 1% flexure strain for exure of a material with a Poisson ratio of −1. An inverted honeycomb based micro-electro-mechanical-systems (MEMS) flexure, with a Poisson atio of −1, was fabricated in silicon and characterized. 2006 Elsevier B.V. All rights reserved.