Tunable micromechanical optical filter using a torsional structure

We demonstrated a torsional micromechanical tunable optical filter with potentially far large tuning range and free of damages resulting from capacitor discharge. The tuning range is above 100 nm and was limited by the tunable source available for testing. The insertion of the filter in an optical data link causes no power penalty. The torsional MEMS design can be readily transferred to a tunable VCSEL and detector designs to lead to a wider tuning range and to eliminate the reliability issues. This program was supported by NSF and DARPA. Carlos F.R. Mateus is supported by CAPES Foundation and Brazilian Air Command.

1. Introduction

Tunable optical filters are key components for various applications, such as dense wavelength division multiplexed (DWDM) optical networks, spectroscopy, beam steering and optical sensing. Various different structures have been reported.^[1]–[7] The micromechanically actuated optical filters are desirable because of their wide tuning range and process compatibility with other optoelectronic devices. A wide and continuous tuning range was demonstrated first in a family of micro-electro-mechanical (MEM) photonic devices using a simple cantilever structure.^[2]–[5] The devices included tunable filters, detectors and vertical cavity surface emitting lasers (VCSELs) with the last being now a commercial product from Bandwidth9, Inc. Other research teams also reported tunable photonic devices using similar cantilever structure^[6] or membrane structures.^[7]