Tunable Bragg grating based on MOEMS technology

摘要

Tunable wavelength selective and band pass filters are widely used nowadays in transmission technology and light processing, with setups based on Acustooptic modulators, Fabry Perrot filters, Mach Zehnder and Sagnac interferometers and fiber Bragg gratings (FBGs) with electro-optical, mechanical or thermal tuning mechanism. Multilayer structures like FBGs are used in the design of e.g. broad-band terminations of transmission lines, narrow-band transmission filters for wavelength-division multiplexing (WDM) and in other fiber optics systems for signal processing. One of the biggest advantages of dielectric mirrors is that they are characterized with very small losses, as compared with normal metallic mirrors. Apart from that, with the use of Bragg mirrors one can control bandwidth of the reflected light beam, as well as the angles for which the reflection is obtained. This opens up a possibility of building setups sensitive to such parameters as the lighting angle and the wavelength. Additionally, Bragg mirrors can be used for a wide spectrum of the electromagnetic waves from UV to FIR. In this paper we propose a new concept of MOEMS-based free-space tunable Bragg grating as a wavelength selective and band pass filter. The use of MEMS allows obtaining fast and reliable tuning with respect to other methods.