| 摘要 |
PROBLEM TO BE SOLVED: To provide a waveguide type optical coupler having coupling rates with small wavelength dependence in a wide wavelength band by shortening a circuit length of an optical coupler by shortening an optical length differences in arm parts of a Mach-Zehnder interferometer. SOLUTION: The waveguide type optical coupler is constituted of the Mach-Zehnder interferometer including three directional couplers and two arm parts for connecting them. For minimizing the wavelength dependence of the coupling rate of the optical coupler, the waveform dependence is adjusted by characterizing respective terms given to a calculating formula of coupling rates and giving a fundamental relationship to coupling phases θ<SB POS="POST">1</SB>, θ<SB POS="POST">2</SB>, and θ<SB POS="POST">3</SB>of the directional couplers and optical path length differences S<SB POS="POST">12</SB>and S<SB POS="POST">23</SB>of the arm parts. COPYRIGHT: (C)2012,JPO&INPIT |
