BROADBAND LIGHT SIGNAL PROCESSOR AND ITS DESIGNING METHOD

摘要

PROBLEM TO BE SOLVED: To make an operating wavelength range wide by using a directional coupler which has wavelength-nondependent characteristics as well amplitude characteristics and phase characteristics or a directional coupler which has a variable amplitude value wavelength-nondependent characteristics as well as amplitude characteristics and phase characteristics. SOLUTION: N+1 two-input, two-output wavelength-nondependent variable directional couplers 3-n (n=1, 2...N+1) which have constant amplitude characteristics and phase characteristics in their operating wavelength ranges are arrayed in a line on a silicon substrate 5 and mutually adjacent wavelength- nondependent variable directional couplers at N places are each coupled by two optical waveguides 1-n and 2-n (n=1, 2...N) having a different optical path length differenceΔL (corresponding to a delay timeΔτ). The optical path length difference between every two of the optical waveguides at the N places is set equally toΔL. Then phase controllers 4-(2n-1) and 4-2n (n=1, 2...N) for controlling phases are installed on every two optical waveguides.