Patent ID: 7359581
Filing Date: 2008-04-15
Classification: G02B,G02F

Abstract:
1. An optical waveguide modulator, equipped with an output light monitor, comprising: an optical waveguide element comprising a dielectric substrate and an optical waveguide formed on a front surface of the dielectric substrate, the optical waveguide comprising a plurality of surface optical waveguide portions, an optical waveguide connecting portion on which the surface optical waveguide portions are converged and connected to each other, and an output light-outputting optical waveguide portion connected to the optical waveguide-connecting portion; an optical fiber for output light, connected to an output end of the output light-outputting optical waveguide portion; a reinforcing capillary for reinforcing a connection between the optical waveguide element and the output light-outputting optical fiber; and means for receiving monitoring light, wherein (1) the optical waveguide further comprises a monitoring light-outputting optical waveguide portion connected to the waveguide-connecting portion to output the monitoring light through the output end of the monitoring light-outputting optical waveguide portion; (2) the monitoring light-outputting optical waveguide portion is coupled to the waveguide-connection portion connected to the plurality of surface waveguide portions, through a directional coupler, a cross-coupler structure, or a tap coupler structure; (3) the reinforcing capillary is provided with a hole or groove formed therein for containing and holding the optical fiber for output light, a connection surface thereof connected to an output end side surface of the dielectric substrate, and a terminal surface thereof opposite to the connection surface, the terminal surface including a light-reflecting surface portion thereof; (4) the output end of the output light-outputting optical waveguide portion is connected to an input end of an optical fiber inserted into the hole or groove of the reinforcing capillary; (5) the reinforcing capillary is formed from transparent glass and configured to enable the monitoring light outputted from the output end of the monitoring light outputting waveguide portion to transmit and permeate from the connection surface to the terminal surface through the reinforcing capillary, to be reflected on the light-reflecting surface portion provided in the terminal surface of the reinforcing capillary, and to be received by the monitoring light-receiving means; (6) the output end of the output light-outputting optical waveguide portion and the output end of the monitoring light-outputting optical waveguide portion are spaced from each other at a distance, the distance being sufficiently large not to cause the monitoring light outputted from the monitoring light-outputting optical waveguide portion and passing through the reinforcing capillary to be affected by the output light outputted from the output end of the output light-outputting optical waveguide portion; (7) the light-reflecting surface portion of the terminal surface of the reinforcing capillary intersects an optical axis of the monitoring light-outputting optical waveguide portion at an oblique angle, to enable the monitoring light outputted from the output end of the monitoring light-outputting optical waveguide portion and transmitted through the reinforcing capillary to be reflected on the light-reflecting surface portion toward the monitoring light-receiving means, and (8) the monitoring light-receiving means is located in a position in which the monitoring light outputted from the reinforcing capillary to the outside of the capillary can be received, and is provided with a photoelectric conversion element.