| 摘要 |
PURPOSE:To obtain an optical wavelength filter capable of ensuring a larger number of selective wavelength channels than a conventional filters, and reducible in size. CONSTITUTION:This optical wavelength filter has a directional coupler 13 with two or more waveguides 13a, 13b different from each other in refractive index or equiv. refractive index, gratings 19 fitted to the waveguides 13a, 13b and causing Bragg reflection at many wavelengths and electrodes 15a, 15b for controlling the difference in refractive index or equiv. refractive index between the waveguides 13a, 13b and the refractive index of each of the waveguides. |
