Vertical cavity surface emitting laser with active layer-specific addressability

Abstract

A vertical cavity surface emitting laser (VCSEL) may include an epitaxial structure that includes a first active layer, a second active layer, and a tunnel junction therebetween. The VCSEL may include a set of contacts that are electrically connected to the epitaxial structure. The set of contacts may include three or more contacts, and the set of contacts may be electrically separated from each other on the VCSEL. At least one contact, of the set of contacts, may be electrically connected to the epitaxial structure at a depth between the first active layer and the second active layer.

What is claimed is: 
     
         1 . A vertical cavity surface emitting laser (VCSEL), comprising:
 an epitaxial structure that includes a first active layer, a second active layer, a third active layer, a first tunnel junction between the first active layer and the second active layer, and a second tunnel junction between the second active layer and the third active layer; and   a set of contacts that are electrically connected to the epitaxial structure,
 wherein the set of contacts includes four or more contacts, 
 wherein the set of contacts are electrically separated from each other on the VCSEL, and 
 wherein the set of contacts is configured to separately address at least one of the first active layer, the second active layer, or the third active layer. 
   
     
     
         2 . The VCSEL of  claim 1 , wherein each contact, of the set of contacts, is electrically connected to the VCSEL at a depth that is different from another depth at which each other contact, of the set of contacts, is electrically connected to the VCSEL. 
     
     
         3 . The VCSEL of  claim 1 , wherein a number of contacts included in the set of contacts is one more than a number of active layers. 
     
     
         4 . The VCSEL of  claim 1 , wherein:
 a first pair of contacts, of the set of contacts, is configured to provide electrical current to only the first active layer,   a second pair of contacts, of the set of contacts, is configured to provide electrical current to only the first active layer and the second active layer, and   a third pair of contacts, of the set of contacts, is configured to provide electrical current to the first active layer, the second active layer, and the third active layer.   
     
     
         5 . The VCSEL of  claim 4 , wherein the first pair of contacts is addressable to provide a first power level for the VCSEL, the second pair of contacts is addressable to provide a second power level for the VCSEL that is greater than the first power level, and the third pair of contacts is addressable to provide a third power level for the VCSEL that is greater than the second power level. 
     
     
         6 . The VCSEL of  claim 1 , wherein:
 a first contact, of the set of contacts, is electrically connected to the epitaxial structure at a depth between the first active layer and the second active layer, and   a second contact, of the set of contacts, is electrically connected to the epitaxial structure at a depth between the second active layer and the third active layer.   
     
     
         7 . The VCSEL of  claim 6 , wherein a third contact, of the set of contacts, is electrically connected to the epitaxial structure at a top surface of the epitaxial structure. 
     
     
         8 . The VCSEL of  claim 7 , wherein a fourth contact, of the set of contacts, is located at a back side of the VCSEL in electrical contact with a substrate of the VCSEL. 
     
     
         9 . The VCSEL of  claim 1 , wherein at least three contacts, of the set of contacts, are electrically connected to the epitaxial structure via a gap in an electrical isolation layer. 
     
     
         10 . The VCSEL of  claim 9 , wherein the gap is in a lateral section of the electrical isolation layer. 
     
     
         11 . The VCSEL of  claim 10 , wherein the lateral section of the electrical isolation layer is within a trench associated with the VCSEL. 
     
     
         12 . A vertical cavity surface emitting laser (VCSEL) array, comprising:
 an epitaxial structure that includes a first active layer, a second active layer, a third active layer, a first tunnel junction between the first active layer and the second active layer, and a second tunnel junction between the second active layer and the third active layer;   at least a first VCSEL and a second VCSEL defined in the epitaxial structure; and   a set of contacts that are electrically connected to the epitaxial structure,
 wherein the set of contacts includes four or more contacts, 
 wherein the set of contacts are electrically separated from each other on the VCSEL array, and 
 wherein the set of contacts is configured to separately address at least one of the first active layer, the second active layer, or the third active layer. 
   
     
     
         13 . The VCSEL array of  claim 12 , wherein each contact, of the set of contacts, is electrically connected to the epitaxial structure at a depth that is different from another depth at which each other contact, of the set of contacts, is electrically connected to the epitaxial structure. 
     
     
         14 . The VCSEL array of  claim 12 , wherein a number of contacts included in the set of contacts is one more than a number of active layers. 
     
     
         15 . The VCSEL array of  claim 12 , wherein:
 a first pair of contacts, of the set of contacts, is configured to provide electrical current to only the first active layer,   a second pair of contacts, of the set of contacts, is configured to provide electrical current to only the first active layer and the second active layer, and   a third pair of contacts, of the set of contacts, is configured to provide electrical current to the first active layer, the second active layer, and the third active layer.   
     
     
         16 . The VCSEL array of  claim 15 , wherein the first pair of contacts is addressable to provide a first power level for the first VCSEL, and the second pair of contacts is addressable to provide a second power level for the second VCSEL. 
     
     
         17 . The VCSEL array of  claim 12 , wherein:
 a first contact, of the set of contacts, is electrically connected to the epitaxial structure at a depth between the first active layer and the second active layer, and   a second contact, of the set of contacts, is electrically connected to the epitaxial structure at a depth between the second active layer and the third active layer.   
     
     
         18 . The VCSEL array of  claim 17 , wherein a third contact, of the set of contacts, is electrically connected to the epitaxial structure at a top surface of the epitaxial structure. 
     
     
         19 . The VCSEL array of  claim 12 , wherein at least three contacts, of the set of contacts, are electrically connected to the epitaxial structure via a gap in an electrical isolation layer. 
     
     
         20 . The VCSEL array of  claim 19 , wherein the gap is in a lateral section of the electrical isolation layer and within a trench associated with the VCSEL array.