Distributed feedback laser diode and distributed feedback laser diode fabrication method

Abstract

A distributed feedback laser diode includes a substrate, an active layer located above and supported by the substrate, and a diffraction grating having a first feature and a second feature and being configured to diffract light generated in the active layer, the second feature being shorter than the first feature and facing a central portion of the first feature.

1 . A distributed feedback laser diode comprising:
 a substrate;   an active layer located above and supported by the substrate; and   a diffraction grating comprising a first feature and a second feature and configured to diffract light generated in the active layer, the second feature being shorter than the first feature and facing a central portion of the first feature.   
     
     
         2 . The distributed feedback laser diode according to  claim 1 , wherein length of the first feature and length of the second feature are each within a range of 3 μM to 10 μM. 
     
     
         3 . A distributed feedback laser diode comprising:
 a substrate;   an active layer located above and supported by the substrate; and   a diffraction grating comprising a plurality of features and being configured to diffract light generated in the active layer, wherein each of the plurality of features includes a plurality of dots, each of the dots having a length of not less than 2.5 μM.   
     
     
         4 . A method of fabricating a distributed feedback laser diode, comprising:
 forming a diffraction grating layer above and supported by a substrate;   forming a conductive layer above and supported by the diffraction grating layer;   forming a resist on the conductive layer;   applying an electron beam and drawing a diffraction grating feature on the resist by electron beam lithography; and   forming a diffraction grating by etching the diffraction grating layer and leaving a portion of the diffraction grating layer, the portion of the diffraction grating layer being directly under the diffraction grating feature.   
     
     
         5 . The method of fabricating a distributed feedback laser diode according to  claim 4 , further comprising, after the formation of the diffraction grating layer and before the formation of the conductive layer, forming an insulating layer on the diffraction grating layer. 
     
     
         6 . The method of fabricating a distributed feedback laser diode according to  claim 4 , wherein the conductive layer comprises tungsten. 
     
     
         7 . A method of fabricating a distributed feedback laser diode, comprising:
 forming a diffraction grating layer above and supported by a substrate;   forming an insulating layer patterned into a strip on the diffraction grating layer;   forming a resist on the insulating layer and the diffraction grating layer and making a portion of the resist on the insulating layer thinner than a portion of the resist on the diffraction grating layer;   applying an electron beam to the resist on the insulating layer and drawing a diffraction grating feature by electron beam lithography; and   forming a diffraction grating by etching the diffraction grating layer and leaving a portion of the diffraction grating layer directly under the diffraction grating feature.