| 摘要 |
PURPOSE:To obtain the light waves of two different frequencies having a low differential frequency and to reduce the size of the titled shifter by changing periodically the refractive index of the branch part of an optical waveguide for output branching at a prescribed angle into a Y shape from the terminal of an optical guide for input. CONSTITUTION:The frequencies of the incident light IB and surface acoustic wave SAW1 of an optical waveguide 12 in a waveguide branched at a prescribed angle into a Y shape from the terminal of an optical waveguide for input are respectively designated as f(lambda) and F1. If the equation sintheta1=lambdaF1/2V is satisfied, the light IB is partly Bragg-diffracted and deflected at 2theta1 angle by interaction with the SAW1 in a branch part 17. The deflected light advances to an optical waveguide 13 and the frequency f+F1 of the deflected light D1 is obtd. If the frequencies F2 and (f) and angle theta2 of the SAW2 satisfy the above-described equation as well, the light IB is partly Bragg-diffracted and deflected at 2theta2 angle by interaction with the SAW2 in the branch part 17. The deflected light advances to the waveguide 14 and the frequency of the deflected light D2 attains f+F2. The light D1 of the frequency f+F1 and the light D2 of f+F2 are respectively obtd. from the waveguides 13, 14 and the differential frequency is ¦F1- F2¦. |
