Electrostatically tunable MOEMS waveguide Bragg grating-based DWDM optical filter

Poorna Lakshmi Uppalapati,Narayan Krishnaswamy,Balasubramanian Malayappan

doi:10.1117/1.jmm.18.1.015503

Abstract

An electrostatically actuated MEMS cantilever beam-based waveguide Bragg grating tunable optical filter has been designed and simulated. The tunable filter is obtained by shifting the reflected wavelength of the waveguide Bragg grating located on the electrostatically actuated cantilever beam. An approach to increasing the electrostatic actuation of the beam by having an electrode underneath the beam is used and a large wavelength tuning range for the optical filter is achieved. Dimensions of the device are chosen such that full-width-half-maximum is 0.75 nm, thus capable of filtering adjacent channels of the dense wavelength division multiplexing (DWDM) network. The filter has a tuning range of 10.65 nm (1552.52 to 1563.17 nm) providing add/drop functionality for 14 adjacent DWDM channels.

Highlights

When the micromachining and electronic properties of silicon are combined with a layer of an oxide of silicon (SOI), a high refractive index contrast optically transparent medium is obtained for wavelength division multiplexing (WDM) applications
Silicon on insulator bandpass filters in Mach–Zehnder configuration with one arm loaded with a ring resonator has been demonstrated[6] where filter bandwidth can be tuned from 10% to 90% of free-spectral range (FSR) at an acceptable off-band rejection
The waveguide and grating carrying dense WDM networks (DWDM) optical signal is on the top surface of the largely insulating (SiO2) beam of 5.1 μm thickness

Summary

Introduction

When the micromachining and electronic properties of silicon are combined with a layer of an oxide of silicon (SOI), a high refractive index contrast optically transparent medium is obtained for wavelength division multiplexing (WDM) applications. Compact ring resonators can be used as spectral filters and very narrow full-width half-maximum of 200 pm has been reported using ring resonator filters but they suffer from low tunable range through effective index variation.[7,8] Waveguide gratings as integrated filters have a footprint smaller than MZI but larger than a ring resonator. They are capable of being widely tuned while having frequency selectivity necessary for DWDM network. Integrated tunable devices designed to tune filter bandwidth, peak amplitude, or FSR are wave-

Methods

Results

Conclusion