A Tunable Filter Based on Grating

Abstract

In a grating-based tunable filter, an input beam comprising multiple wavelengths is directed into the input fiber of a circulator. The beam is collimated and then reflected by a rotating flat mirror. The beam is then amplified and transmitted to and through a transmission diffraction grating which deflects the different wavelengths of the transmitted beam to different angles. The wavelengths are transmitted to a flat mirror and reflected, only a very small portion of the wavelength spectrum of the transmitted beam will be reflected back along the input path, and then transmitted to the output fiber.

Description

[0001] Cross reference to related applications [0002] This application claims priority to US Provisional Patent Application No. 13 / 441,899, entitled "A Grating-Based Tunable Filter," filed April 8, 2012, which is incorporated herein by reference. technical field [0003] The present invention relates to reconfigurable optical networks and spectrometer scan engines, and more particularly to tunable filters usable in the networks and engines. Background technique [0004] Various types of tunable optical filters are known in the art. Commonly used filters include rotating or tilting thin film bandpass optical filters, linear variable thin film filters, electrically controlled, thermally controlled or acoustically controlled wavelength tunable etalons, and thin film filter structures with thermally sensitive cavity layers located between reflective layers. US Patent No. 7,899,330, entitled "Compact High Resolution Tunable Optical Filter Using Light Diffractive Elements and ...

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Problems solved by technology

This greatly increases the total dispersion angle, resulting in highly adjacent channel separation

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