High power top emitting vertical cavity surface emitting laser

Abstract

A laser device including a VCSEL array provides an increased power density at a high wall-plug efficiency in that the lateral design parameters are appropriately selected on the basis of a relationship that has been established for a specified vertical design, a corresponding process technology and specified operating conditions. Thus, the total output power, the power density, and the efficiency may be optimized independently from other design criteria and application requirements by tuning only the lateral size of the individual VCSEL elements and the pitch of nearest neighbors of the elements within the array. Hence, for a lateral size of less than 30 μm and a pitch of less than 80 μm, a highly efficient VCSEL array can be provided with a high power density, thereby optimizing manufacturing costs for the output power per chip area.

1 . A metal contact laser device comprising: 
 a substrate,    a plurality of vertical cavity surface emitting laser elements formed on said substrate, each of said VCSEL elements having an effective laser active region with a respective defined center point and a defined lateral size, said defined lateral size of each VCSEL element being equal to or less than 30 μm,    wherein a pitch between the center points of nearest neighbors of said VCSEL elements is equal to or less than 80 μm.    
   
   
       2 . The laser device of  claim 1 , further comprising a first current terminal and a second current terminal, wherein each of said VCSEL elements is connected to said first and second current terminals.  
   
   
       3 . The laser device of  claim 1 , wherein each of said VCSEL elements comprises a radiation output window that is disposed oppositely to said substrate.  
   
   
       4 . The laser device of  claim 1 , wherein each of said VCSEL elements has a configuration corresponding to the same design.  
   
   
       5 . The laser device of  claim 1 , wherein said pitch between nearest neighbors of each VCSEL element is substantially identical for each of the VCSEL elements.  
   
   
       6 . The laser device of  claim 5 , wherein said plurality of VCSEL elements are arranged in a honeycomb pattern.  
   
   
       7 . The laser device of  claim 1 , wherein each of said VCSEL elements is located on a site of a lattice and at least one lattice site is occupied by a bond pad.  
   
   
       8 . The laser device of  claim 1 , wherein the pitch to nearest neighbors of a first VCSEL element differs from the pitch to nearest neighbors of a second VCSEL element.  
   
   
       9 . The laser device of  claim 1 , further comprising an aperture layer having formed therein an aperture that substantially determines said defined lateral size of said effective laser active region.  
   
   
       10 . The laser device of  claim 9 , wherein said aperture layer comprises an oxidized periphery to define said aperture within said periphery.  
   
   
       11 . The laser device of  claim 1 , wherein a layer stack forming at least a portion of said laser device comprises a periphery modified by ion implantation to define an aperture within said periphery.  
   
   
       12 . The laser device of  claim 1 , wherein said defined lateral size of the effective laser active region of a first VCSEL element differs from said defined lateral size of the effective laser active region of a second VCSEL element.  
   
   
       13 . The laser device of  claim 1 , wherein said defined lateral size of the effective laser active region of each VCSEL element is equal to or greater than 10 μm.  
   
   
       14 . The laser device of  claim 1 , wherein said pitch between nearest neighbors of each of the VCSEL elements is equal to or greater than 40 μm.  
   
   
       15 . The laser device of  claim 1 , wherein said pitch between nearest neighbors of each of the VCSEL elements is in the range of 55 μm and 65 μm.  
   
   
       16 . The laser device of  claim 1 , wherein said effective laser active region has a substantially circular shape.  
   
   
       17 . The laser device of  claim 1 , further comprising a contiguous metal layer for electrically connecting said plurality of VCSEL elements.  
   
   
       18 . The laser device of  claim 17 , wherein said contiguous metal layer covers all of the array except for said VCSEL elements.  
   
   
       19 . A method of adjusting a power density of a metal contact VCSEL array, the method comprising: 
 establishing a relationship for a specified test array between an effective lateral size of a laser active region of VCSEL elements of a defined design, a pitch of nearest neighbors of said VCSEL elements when arranged according to said specified test array and a power output by said test array,    determining positions of VCSEL elements having said defined design within said VCSEL array on the basis of said relationship, and    manufacturing said VCSEL array with VCSEL elements of said defined design by forming the VCSEL elements substantially at said determined positions.    
   
   
       20 . The method of  claim 19 , further comprising determining a desired range for said power density on the basis of a desired operating current range and a pitch of nearest neighbors determined by a selected manufacturing technology, wherein said desired power density range includes a maximum of said power density for said desired operating current range.  
   
   
       21 . The method of  claim 20 , wherein said pitch is a minimum pitch for said selected manufacturing technology.  
   
   
       22 . The method of  claim 19 , further comprising determining a desired effective lateral size of the laser active region for said VCSEL elements so as to obtain a power density that lies within said desired power density range.  
   
   
       23 . The method of  claim 22 , wherein manufacturing said VCSEL array includes forming a current aperture having said desired size by selectively oxidizing a material layer to obtain a conductive non-oxidized layer portion as said current aperture.  
   
   
       24 . The method of  claim 22 , wherein manufacturing said VCSEL array includes forming a current aperture having said desired size by modifying a material layer stack by ion implantation so as to obtain a conductive non-modified layer portion as said current aperture.  
   
   
       25 . The method of  claim 19 , further comprising 
 determining data corresponding to a wall-plug efficiency of said specified test array for a plurality of different pitches and effective lateral sizes, and    determining said array positions on the basis of said data.    
   
   
       26 . The method of  claim 25 , wherein said data are derived from measurement results obtained from said test array.  
   
   
       27 . The method of  claim 19 , further comprising estimating a heat distribution of said VCSEL array for predefined operating conditions and selecting said pitches and/or said effective lateral sizes on the basis of the estimated heat distribution.  
   
   
       28 . The method of  claim 27 , wherein the pitch for VCSEL elements to be positioned on an area of increased temperature is selected greater than for VCSEL elements located at an area of reduced temperature.  
   
   
       29 . The method of  claim 27 , wherein the lateral size for VCSEL elements to be positioned on an area of increased temperature is selected greater than for VCSEL elements located at an area of reduced temperature.