Patent ID: 8682121
Filing Date: 2014-03-25
Classification: G02B

Abstract:
1. An optical wavelength filter for separating input light having different wavelengths multiplexed into respective wavelengths of light to output the separated wavelengths of light, said filter comprising: a plurality of optical waveguides for propagating the input light from an input end receiving the input light to an output end, each of said plurality of optical waveguides comprising: each of said plurality of optical waveguides being partitioned into a reference section providing a reference and an adjustment section for adjusting a phase difference, said reference section being set to a first partitioning condition in which the optical waveguide in said reference section has a first equivalent refractive index and a first length, said adjustment section being set to a second partitioning condition in which the optical waveguide in said adjustment section has a second equivalent refractive index and a second length, whereby an interference condition is satisfied in which two waves of light outputted from the output ends of adjacent two of said optical waveguides interfere with each other with a predetermined phase difference therebetween, wherein the first and second partitioning conditions are set for one of the different wavelengths of the input light such that, even when an operating ambient temperature varies or said plurality of optical waveguides involve a dimensional error, the interference condition is satisfied to thereby reduce a variation in wavelength characteristic of said filter.