OPTICAL FILTER MULTIPLEXING/DEMULTIPLEXING DEVICE

摘要

An optical filter is provided having first and second graded index (GRIN) le nsespreferably disposed in a coaxial relationship so tha t they have a common optical axis. Each of the GRIN lenses have an endface providing a port at predetermined lo cation. The ports are disposed on opposite sides of the optical axis and each of the ports are substantially equidistant from the optical axis, so as to be oppositely offs et from the optical axis by a same amount. The filter also includes an optical interfere nce filter disposed between other endfaces of the first and second graded index lenses. By changing the location of the ports by a same small amount, the center wavelength of t he filter changes by a small amount, thus in manufacture, the filter is tunable. After tuning the filter to a desired wavelength, the locations of the ports are fixed.