Optical semiconductor device

Abstract

An optical semiconductor device includes: semiconductor lasers; a wave coupling section multiplexing light output by the semiconductor lasers; an optical amplifying section amplifying output light of the wave coupling section; a first optical waveguide optically connecting respective semiconductor lasers to the wave coupling section; a second optical waveguide optically connecting the wave coupling section to the optical amplifying section; a third optical waveguide optically connected to an output of the optical amplifying section; and a phase regulator located in at least one of the first, second, and third optical waveguides, and regulating phase of reflected light that is reflected at a reflecting point in the optical semiconductor device and that returns to the semiconductor lasers. The phase regulator adjusts the phase of the reflected light to decrease line width of the light output by the semiconductor lasers.

1 . An optical semiconductor device comprising:
 a plurality of semiconductor lasers;   a wave coupling section multiplexing light output by the plurality of the semiconductor lasers;   an optical amplifying section amplifying output light of the wave coupling section;   a first optical waveguide optically connecting respective semiconductor lasers to the wave coupling section;   a second optical waveguide optically connecting the wave coupling section to the optical amplifying section;   a third optical waveguide optically connected to an output of the optical amplifying section; and   a phase regulator located in at least one of the first, second, and third optical waveguides, and regulating phase of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the plurality of semiconductor lasers, wherein the phase regulator adjusts the phase of the reflected light to decrease line width of the light output by the plurality of semiconductor lasers.   
     
     
         2 . The optical semiconductor device according to  claim 1 , further comprising a control section adjusting a bias voltage applied to the phase regulator so that the phase regulator adjusts the phase of the reflected light to decrease the line width of the light output by the plurality of semiconductor lasers. 
     
     
         3 . An optical semiconductor device comprising:
 a plurality of semiconductor lasers;   a wave coupling section multiplexing light output by the plurality of the semiconductor lasers;   an optical amplifying section amplifying output light of the wave coupling section;   an optical waveguide optically connecting respective semiconductor lasers to the wave coupling section; and   a light intensity lowering section located in the optical waveguide, and lowering light intensity of reflected light that is reflected at a reflecting point located in the optical semiconductor device and that returns to the plurality of semiconductor lasers, wherein the light intensity lowering section lowers the light intensity of the reflected light to decrease line width of the light output by the plurality of semiconductor lasers.   
     
     
         4 . The optical semiconductor device according to  claim 3 , further comprising a control section adjusting a bias voltage applied to the light intensity lowering section, and making the light intensity lowering section lower the light intensity of the reflected light to decrease the line width of the light output by the plurality of semiconductor lasers. 
     
     
         5 . The optical semiconductor device according to  claim 1 , further comprising an optical modulator optically connected to an output of the optical amplifying section. 
     
     
         6 . The optical semiconductor device according to  claim 3 , further comprising an optical modulator optically connected to an output of the optical amplifying section.