High power top emitting vertical cavity surface emitting laser
A method of adjusting a power density in a laser device including a VCSEL array providing 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 method of manufacturing a Vertical Cavity Surface Emitting Laser (VCSEL) array to a desired power density, comprising the steps of:
establishing, using a first VCSEL array including VCSEL elements, a relationship between an effective lateral size of a laser active region of the VCSEL elements, a pitch between center points of nearest neighbors of the VCSEL elements, and a power output by the first VCSEL array,
determining data corresponding to a wall-plug efficiency of the first VCSEL array for a plurality of different pitches and effective lateral sizes,
determining positions of VCSEL elements in a second VCSEL array on the basis of the relationship and the data, wherein a pitch between center points of nearest neighbors of the VCSEL elements in the second VCSEL array is equal to or less than 80 μm, and a first pitch between center points of a first VCSEL element in the second VCSEL array and a nearest neighbor thereto and a second pitch between center points of a second VCSEL element in the second VCSEL array and a nearest neighbor thereto are different, and
manufacturing the second VCSEL array with the VCSEL elements substantially at the determined positions,
wherein each of the VCSEL elements of the first VCSEL array and the second VCSEL array includes an effective laser active region with a defined center point and with an effective lateral size equal to or less than 30 μm.
2. The method of claim 1 , further comprising the step of:
determining a desired range for the power density of the second VCSEL array based on an operating current range and a pitch of nearest neighbors determined by a selected manufacturing technology, wherein a maximum power density of the second VCSEL array operating within the operating current range is within the desired range for the power density of the second VCSEL array.
3. The method of claim 2 , further comprising the step of:
determining a desired effective lateral size of the laser active region for said VCSEL elements of the second VCSEL array so as to obtain a power density that lies within the desired range for the power density.
4. The method of claim 3 , wherein:
said step of manufacturing the second VCSEL array includes forming a current aperture to a desired size by selectively oxidizing a material layer to obtain a conductive non-oxidized layer portion as the current aperture.
5. The method of claim 3 , wherein:
said step of manufacturing the second VCSEL array includes forming a current aperture to a desired size by modifying a material layer stack through ion implantation so as to obtain a conductive non-modified layer portion as the current aperture.
6. The method of claim 1 , wherein:
the data are derived from measurement results obtained from the first VCSEL array.
7. A method of manufacturing a Vertical Cavity Surface Emitting Laser (VCSEL) array to a desired power density, comprising the steps of:
establishing, using a first VCSEL array including VCSEL elements, a relationship between an effective lateral size of a laser active region of the VCSEL elements, a pitch between center points of nearest neighbors of the VCSEL elements, and a power output by the first VCSEL array,
estimating a heat distribution of the second VCSEL array for predefined operating conditions and selecting the pitches and/or the effective lateral sizes for the VCSEL elements in the second VCSEL array on the basis of the estimated heat distribution,
determining positions of VCSEL elements in a second VCSEL array on the basis of the relationship and the estimated heat distribution, wherein a pitch between center points of nearest neighbors of the VCSEL elements in the second VCSEL array is equal to or less than 80 μm, and a first pitch between center points of a first VCSEL element in the second VCSEL array and a nearest neighbor thereto and a second pitch between center points of a second VCSEL element in the second VCSEL array and a nearest neighbor thereto are different, and
manufacturing the second VCSEL array with the VCSEL elements substantially at the determined positions,
wherein each of the VCSEL elements of the first VCSEL array and the second VCSEL array includes an effective laser active region with a defined center point and with an effective lateral size equal to or less than 30 μm.
8. The method of claim 7 , wherein:
the pitch for VCSEL elements in the second VCSEL array that are to be positioned in an area of increased temperature is greater than the pitch for VCSEL elements in the first VCSEL array that are to be positioned in an area of reduced temperature.
9. The method of claim 7 , wherein:
the lateral size for VCSEL elements in the second VCSEL array that are to be positioned in an area of increased temperature is greater than the lateral size for VCSEL elements in the first VCSEL array that are to be positioned in an area of reduced temperature.