| 摘要 |
PROBLEM TO BE SOLVED: To enable to obtain optical path lengths of all array waveguides with single measurement. SOLUTION: In an optical path length measuring apparatus of an array waveguide grating, a 1.5μm LED light 81 and a 1.3μm LED light are made to enter a Mach-Zehnder interference optical system constituted of photo couplers 51, 52, an array waveguide grating 31, an optical path length changing device 32 and an optical attenuator 34. A light 82 propagating through the grating 31 and a reference light 83 propagating through the changing device 32 and the attenuator 34 are combined and branched with a wavelength branching filter 33, and a beat signal 84 generated by interference of the lights 82 and 83 is subjected to Fourier transformation, thereby obtaining the optical path length of an array waveguide. By adjusting the attenuator 34, the ratio of the lights 82 and 83 is optimized, and an amplitude of the beat signal 84 greater than or equal to the optical noise entering a photo detector 41 and the electric noise in the case of electric conversion is obtained. |
