Wavelength selective optical routers

Abstract

Using the wavelength selectivity and low loss characteristics of optical couplers, in which index of refraction gratings in a non-evanescent waveguide merged region reflect only a selected wavelength band, signal switching and control systems of novel characteristics are provided for multi-wavelength optical communication systems. In a router, for example, selected wavelengths or wavelength bands on an add/drop line can be added to or dropped from a main fiber, by cross switching between wavelength selective loops disposed sequentially in the lines. In a collector box, as another example, selected wavelength bundles can be routed from one fiber onto multiple fibers. In a bandpass filter a selected wavelength band is transmitted with low loss while those wavelengths outside the selected wavelength band are rejected with very high loss.