STACKABLE NARROWBAND FILTERS FOR DENSE WAVELENGTH DIVISION MULTIPLEXING

摘要

A plane-parallel optical window is the spacer of single-cavity filters in the stack used for DWDM applications. Highly reflective quarter-wave stacks are deposited on each side of the optical window and the single-cavity structure so obtained is diced to produce a plurality of filters. Because the single-cavity structure has the same thickness over the entire window area and the quarter-wave-stack deposition process is carried out throughout under the same conditions, each single-cavity filter fabricated from the optical window has the same transmission wavelength and is therefore readily stackable for DWDM applications. Alternatively, an optical window with a thickness equal to one half that required for the spacer of a single-cavity filter is coated on a single side. The window is then divided in multiple identical components that can be combined in pairs by placing them in optical contact so as to form individual single-cavity filters with the same transmission wavelength.