Patent ID: 7580593
Filing Date: 2009-08-25
Classification: G02F

Abstract:
1. An optical attenuator that attenuates light inputted through an input optical waveguide and outputs the light from an output optical waveguide, comprising: a first optical waveguide connected to the input optical waveguide; a second optical waveguide connected to the output optical waveguide; and a connecting optical waveguide connecting the first optical waveguide with the second optical waveguide are connected in series, wherein the first optical waveguide comprises a first diffuse part which is formed so that an optical waveguide width thereof becomes broader as extending from the input optical waveguide toward the connecting optical waveguide; a first attenuating part which is interposed between the first diffuse part and the connecting optical waveguide and also formed so that an optical waveguide width of the first attenuating part becomes narrower as directing toward the connecting optical waveguide; a first recess which is arranged on one side of the first attenuating part in a width direction of an optical waveguide thereof; and a first optical attenuating heater which is arranged on the other side of the first attenuating part having the first recess in a width direction of an optical waveguide of the first attenuating part and also arranged so as to overlap with a part of the first attenuating part in a thickness direction of the first optical waveguide; the second optical waveguide comprises a second diffuse part which is formed so that an optical waveguide width thereof becomes broader as extending from the connecting optical waveguide toward the output optical waveguide; a second attenuating part which is interposed between the second diffuse part and the output optical waveguide and also formed so that an optical waveguide width of the second attenuating part becomes narrower as directing toward the output optical waveguide; a second recess which is arranged on one side of the second diffuse part in a width direction of an optical waveguide thereof or one side of the second attenuating part in a width direction of an optical waveguide thereof; and a second optical attenuating heater which is arranged on the other side of the optical waveguide having the second recess in the width direction and also arranged so as to overlap with a part of the second diffuse part or the second attenuating part in a thickness direction of the second optical waveguide; the first recess and the second recess are formed in a positional relationship of opposite directions with respect to an axial direction of an optic axis of light that is inputted through the input optical waveguide, transmitted through the first optical waveguide, the connecting optical waveguide and the second optical waveguide and outputted from the output optical waveguide; and the first optical attenuating heater and the second optical attenuating heater are arranged so as to produce opposite refractive index distributions in the axial direction of the optic axis of the light that is inputted through the input optical waveguide, transmitted through the first optical waveguide, the connecting optical waveguide and the second optical waveguide and outputted from the output optical waveguide, in the first optical waveguide and the second optical waveguide.