Semiconductor laser array

Abstract

A semiconductor laser array includes a plurality of stripe-shaped stimulated regions of the index guide type. A plurality of buried layers are disposed between each of the plurality of stripe-shaped stimulated regions. A light absorption layer is formed in each of the plurality of stripe-shaped stimulated regions so that the stimulated region has the optical loss greater than an buried layer, whereby optical coupling is performed with no phase difference.

What is claimed is: 
     
       1. A semiconductor element in a semiconductor laser array comprising: a semiconductor substrate;   a plurality of stripe-shaped stimulated regions of an index guide type formed on said semiconductor substrate;   a plurality of buried layers, a buried layer being disposed between adjacent ones of said plurality of stripe-shaped stimulated regions, wherein said plurality of stripe-shaped stimulated regions comprise a light absorption layer so that said plurality of stripe-shaped stimulated regions have an optical loss greater than an optical loss of said plurality of buried layers;   a first electrode formed commonly on said plurality of stripe-shaped stimulated regions; and   a second electrode formed on a bottom surface of said semiconductor substrate.   
     
     
       2. A semiconductor laser array comprising: a semiconductor substrate;   a first cladding layer formed on said semiconductor substrate;   an active layer formed on said first cladding layer;   a second cladding layer formed on said active layer;   a plurality of stripe-shaped stimulated regions formed on said second cladding layer, each of said plurality of stripe-shaped stimulated regions including: a light absorption layer formed on said second cladding layer;   a third cladding layer formed on said light absorption layer; and   a cap layer formed on said third cladding layer:     a plurality of buried layers disposed between each of said plurality of stripe-shaped stimulated regions;   a plurality of oxide films formed on each of said plurality of buried layers;   a first electrode formed commonly on said plurality of stripe-shaped stimulated regions and said plurality of oxide films; and   a second electrode formed on the bottom surface of said semiconductor substrate.   
     
     
       3. A GaAlAs semiconductor laser array comprising: an n-GaAs substrate;   An n-Ga 0 .6 Al 0 .4 As cladding layer formed on said n-GaAs substrate;   a p-Ga 0 .9 Al 0 .1 As active layer formed on said n-Ga 0 .6 Al 0 .4 As cladding layer;   a p-Ga 0 .6 Al 0 .4 As cladding layer formed on said p-Ga 0 .9 Al 0 .1 As active layer;   a plurality of stripe shaped stimulated regions formed on said p-Ga 0 .6 Al 0 .4 As cladding layer, each of said plurality of stripe-shaped stimulated regions including: p-GaAs light absorption layer formed on said p-Ga 0 .6 Al 0 .4 As cladding layer;   a p-Ga 0 .6 Al 0 .4 As cladding layer formed on said p-GaAs light absorption layer; and     a p-GaAs cap layer formed on said p-Ga 0 .6 Al 0 .4 As cladding layer;   a plurality of n-Ga 0 .5 Al 0 .5 As buried layers disposed between each of said plurality of stripe-shaped stimulated regions;   a plurality of oxide films formed on each of said plurality of n-Ga 0 .5 AL 0 .5 As buried layers;   a first electrode formed commonly on said plurality of stripe-shaped stimulated regions and said plurality of oxide films; and   a second electrode formed on the bottom surface of said n-GaAs substrate.   
     
     
       4. The semiconductor element of claim 1 wherein each of said plurality of stripe-shaped stimulated regions formed on said semiconductor substrate further comprise: a cladding layer disposed on said light absorption layer; and   a cap layer formed on said cladding layer.   
     
     
       5. The semiconductor element of claim 4 further comprising a plurality of oxide films each oxide film being disposed on one of said plurality of buried layers. 
     
     
       6. The semiconductor laser array of claim 2 wherein said third cladding layer has a refractive index greater than each of said plurality of buried layers. 
     
     
       7. The semiconductor laser array of claim 2 wherein each of said stripe-shaped stimulated regions have an optical loss greater than an optical loss of said plurality of buried layers. 
     
     
       8. The semiconductor laser array of claim 2 wherein each of said plurality of buried layers includes n-Ga 0 .5 Al 0 .5 As. 
     
     
       9. The semiconductor laser array of claim 2 wherein each of said plurality of buried layers includes p-Ga 0 .5 Al 0 .5 As. .Iadd. 
     
     
       10.  A semiconductor laser device comprising: a semiconductor substrate;   first cladding layer formed on said semiconductor substrate;   an active layer formed on said first cladding layer;   a second cladding layer formed on said active layer and having an area coextensive with a portion of said active layer;   a light absorption layer formed on said second cladding layer over said coextensive area;   a third cladding layer formed on and coextensive with said light absorption layer;   a cap layer formed on and coextensive with said third cladding layer; and   a buried layer formed on said second cladding layer of a thickness subtending said light absorption layer, said third cladding layer and said cap layer. .Iaddend. .Iadd.11. The laser device of claim 10, wherein said light absorption layer and said third cladding layer have a refractive index greater than that of said buried layer. .Iaddend. .Iadd.12. The laser device of claim 10, which further includes a first electrode layer on said substrate opposite said first cladding layer; and   
     
     
       a second electrode layer on said cap layer. .Iaddend. .Iadd.13.  The laser device of claim 12, wherein said third cladding layer has a refractive index greater than that of said buried layer. .Iaddend. .Iadd.14. The laser device of claim 10, wherein said coextensive area of said second cladding layer is of equal or greater thickness than the remainder thereof. .Iaddend. .Iadd.15. The laser device of claim 14, wherein said light absorption layer and said third cladding layer have a refractive index greater than that of said buried layer. .Iaddend. .Iadd.16. The laser device of claim 14, which further includes a first electrode layer on said substrate opposite said first cladding layer; and a second electrode layer on said cap layer. .Iaddend. .Iadd.17. The laser device of claim 16, wherein said third cladding layer has a refractive index greater than that of said buried layer. .Iaddend. .Iadd.18. A semiconductor laser device comprising:   a semiconductor substrate of n-GaAs;   a first cladding layer of n-Ga 0 .6 Al 0 .4 As formed on said substrate;   an active layer of p-Ga 0 .9 Al 0 .1 As formed on said first cladding layer;   a second cladding layer of p-Ga 0 .6 Al 0 .4 As formed on said active layer and having an area coextensive with a portion of said active layer;   a light absorption layer of p-GaAs formed on said second cladding layer over said coextensive area;   a third cladding layer of p-Ga 0 .6 Al 0 .4 As formed on and coextensive with said light absorption layer;   a cap layer of p-GaAs formed on and coextensive with said third cladding layer; and   a buried layer of n-Ga 0 .5 Al 0 .5 As formed on said second cladding layer of a thickness subtending said light absorption layer, said third   
     
     
        cladding layer and said cap layer. .Iaddend. .Iadd.19.  The laser device of claim 18, which further includes a first electrode layer on said substrate opposite said first cladding layer; and a second electrode layer on said cap layer. .Iaddend. .Iadd.20. The laser device of claim 18, wherein said coextensive area of said second cladding layer is of equal or greater thickness than the remainder thereof. .Iaddend. .Iadd.21. The laser device of claim 20, which further includes a first electrode layer on said substrate opposite said first cladding layer; and   
     
     
       a second electrode layer on said cap layer. .Iaddend. .Iadd.22.  The method of manufacturing a semiconductor laser device comprising the steps of: providing a substrate of semiconductor material;   sequentially forming a first cladding layer on said substrate, an active layer on said first cladding layer, a second cladding layer on said active layer, a light absorption layer on said second cladding layer, a third cladding layer on said light absorption layer and a cap layer on said third cladding layer;   forming a mask on said cap layer;   applying a first etchant to said cap layer to remove the unmasked portions of said cap layer and at least some of the corresponding portions of said third cladding layer;   applying a second etchant to said third cladding layer to remove the remainder of said corresponding portions and expose said light absorption layer;   applying a third etchant to said light absorption layer to remove portions thereof corresponding to removed portions of said third cladding layer down to said second cladding layer;   removing said mask;   forming a buried layer on said cladding layer to a depth at least subtending the combined thickness of said light absorption layer, said third cladding layer and said cap layer; and   applying a fourth etchant to said buried layer and said cap layer to reduce   
     
     
        the thickness of said cap layer. .Iaddend. .Iadd.23.  The method of claim 22, which further includes the steps of: forming a first electrode on said cap layer; and   forming a second electrode on said semiconductor substrate opposite said first cladding layer. .Iaddend. .Iadd.24. The method of claim 22, which further includes utilizing said third etchant to remove some of said second cladding layer, leaving a thicker portion thereof in the shape of said mask overlying said active layer. .Iaddend. .Iadd.25. The method of claim 24, which further includes the steps of:   forming a first electrode on said cap layer and said oxide layer; and   forming a second electrode on said semiconductor substrate opposite said first cladding layer. .Iaddend. .Iadd.26. The method of manufacturing a semiconductor laser array comprising the steps of:   providing a substrate of semiconductor material;   sequentially forming a first cladding layer on said substrate, an active layer on said first cladding layer, a second cladding layer on said active layer, a light absorption layer on said second cladding layer, a third cladding layer on said light absorption layer and a cap layer on said third cladding layer;   forming a mask on said cap layer comprising a plurality of parallel stripe-shaped resists;   applying a first etchant to said cap layer to remove the unmasked portions of said cap layer and at least some of the corresponding portions of said third cladding layer;   applying a second etchant to said third cladding layer to remove the remainder of said corresponding portions and expose said light absorption layer;   applying a third etchant to said light absorption layer to remove portions thereof corresponding to removed portions of said third cladding layer down to said second cladding layer;   removing said mask;   forming a buried layer on said second cladding layer to a depth at least subtending the combined thickness of said light absorption layer, said third cladding layer and said cap layer; and applying a fourth etchant to said buried layer and said cap layer to reduce the thickness of said cap   
     
     
        layer. .Iaddend. .Iadd.27.  The method of claim 26, which further includes the steps of: forming a first electrode on said cap layer; and   forming a second electrode on said semiconductor substrate opposite said first cladding layer. .Iaddend. .Iadd.28. The method of claim 26, which further includes utilizing said third etchant to remove some of said second cladding layer, leaving a thicker portion thereof in the shape of said mask overlying said active layer. .Iaddend. .Iadd.29. The method of claim 28, which further includes the steps of:   forming a first electrode on said cap layer; and   forming a second electrode on said semiconductor substrate opposite said   
     
     
        first cladding layer. .Iaddend. .Iadd.30.  The method of manufacturing a semiconductor laser device comprising the steps of: providing a substrate of semiconductor material;   sequentially forming a first cladding layer on said substrate, an active layer on said first cladding layer, a second cladding layer on said active layer, a light absorption layer on said second cladding layer, a third cladding layer on said light absorption layer and a cap layer on said third cladding layer;   forming a mask on said cap layer;   applying a first etchant to said cap layer to remove the unmasked portions of said cap layer and at least some of the corresponding portions of said third cladding layer;   applying a second etchant to said third cladding layer to remove the remainder of said corresponding portions and expose said light absorption layer;   etching said light absorption layer to remove portions thereof corresponding to removed portions of said third cladding layer down to said second cladding layer;   removing said mask;   forming a buried layer on said cladding layer to a depth at least subtending the combined thickness of said light absorption layer, said third cladding layer and said cap layer; and   applying a third etchant to said buried layer and said cap layer to reduce   
     
     
        the thickness of said cap layer. .Iaddend. .Iadd.31.  The method of claim 30 wherein said light absorption layer is etched by a meltback etching technique. .Iaddend.