Patent ID: 7136589

Claim:
A re-configurable optical add-drop multiplexer (OADM) adapted to receive an optical wavelength division multiplexing (WDM) signal, comprising: a first optical circulator having a first circulator port, a second circulator port and a third circulator port, wherein an optical signal passing into the first circulator port is routed to the second circulator port and an optical signal passing into the second circulator port is rooted to the third circulator port; a second optical circulator having a first port, a second port and a third port, wherein an optical signal passing into the first port is routed to the second port and an optical signal passing into the second port is routed to the third port; a fiber Bragg grating (FBG) having an optical fiber, a cooler and a plurality of heating elements, the heating elements being evenly spaced a fixed distance apart and being arranged on the optical fiber, the optical fiber having an optical fiber core made of a material whose index of refraction varies with temperature, the cooler being mounted on the optical fiber for maintaining a plurality of sections between pairs of adjacent heating elements of the optical fiber at a pre-determined temperature, the FBG having a first state in which it reflects an optical signal with a determined wavelength and passes all optical signals having other than the determined wavelength, and a second state in which all the optical signals pass through it; wherein the FBG is connected with the second circulator port of the first optical circulator and the second port of the second optical circulator, and the FBG is in the first state selectively for adding an optical signal in the optical WDM signal through the first port of the second optical circulator and for dropping an optical signal from the optical WDM signal through the third circulator port of the first optical circulator.