| 摘要 |
PROBLEM TO BE SOLVED: To obtain a new combining and branching element, which reduces the transmission loss caused by the wavelength deviation in inputted light beams, by providing a phase difference adding section that gives stepwise phase differences against the wavelength changes in the inputted light beams. SOLUTION: The element is provided with a distributing section 13, which distributes inputted light beams into more than two groups, a phase difference adding section 15, which gives phase difference to the distributed light beams that are distributed by the section 13 in accordance with the wavelengths of the inputted light beams, and a condensing section 17 which condenses the distributed light beams that are distributed into more than two groups and that phase differences are given. The section 15 that provides stepwise phase differences among the distributed light beams in accordance with the changes in the wavelengths of the inputted light beams is provided. Thus, the wave fronts formed by distributed light beams are made same as for the wavelengths of the inputted light beams that are more than an n-th wavelengthλn and less than an n+1 th wavelengthλn+1. Thus, if the wavelength of the inputted light beams is deviated between more than the n th wavelengthλn and less than the n+1 th wavelengthλn+1, the inputted light beams are condensed at a same condensed position and the transmission loss is prevented. |
