| 摘要 |
PURPOSE:To attain low-loss optical fiber coupling and low voltage driving by specifying the diameters of the light spots in the junction parts between each of required input/output optical waveguides and the optical waveguide to a directional coupler. CONSTITUTION:The input optical waveguides 203, 204 of an LiNbO3 substrate 201 have the selectivity of polarized light and are made the same in the diameters of the optical fibers to be coupled and the light spots. The once polarized incident light is made incident through the junction parts 215, 216 and the optical waveguides 202A, 202B to the directional coupler part 208 having electrodes 207. The waveguides 203, 204 in the junction parts 215, 216 are gradually reduced in the diameter of the light spot and the diameter of the light spot of the waveguide 202A, 202B is gradually increased and is made into the specified diameter smaller than the diameter of the light spot of the optical fibers. As for the outgoing waveguides from the coupler 208, it is also similar. The optical control circuit which can make the optical fiber coupling at a low loss and can make the low-voltage driving is obtd. by the constitution to propagate the specified polarized light in the waveguides of the prescribed diameter of the light spot. |
