Patent ID: 8346088

Claim:
The controllable optical add/drop multiplexer for fiber-optic communication system provided with 2 N of wavelength-division multiplexing channels, whose optical frequencies at a constant frequency separation Δv between two adjacent channels are retunable, that have one input port, one output port, one drop port and one add, further comprising: an N-stage structure, where each stage, at n=1, 2, . . . , N, contains an optical filter having one input (g or a) and two outputs (p, κ or e, f) and characterizing by transmission in form periodic function with spectral separation between two adjacent extremums Δv n =2 n-1 ΔV and having a possibility of controllable tuning transmissions; connected between each other the first and the second multi-stage structures having in the first structure has N 1 stages and in the second structure has N 2 stages, N 1 +N 2 =N, and characterizing by transmission in form periodic function and having a possibility of controllable tuning transmissions; an optical combiner ( 96 ), that has Ni+1 inputs and one output; and a controller ( 99 ) for tuning of transmission of said optical filters [ 95 - 1 , . . . 95 - 6 ] of the first and second multi stage structures ( 90 a , 90 b ).