Lasers may be used in LIDAR (Light Detection and Ranging) systems to acquire three-dimensional information of an environment.
For example, a laser can be aimed and the time between activating the laser and receiving a reflection of the laser can be used to determine a distance to the object. If the laser or an array of lasers is aimed in a variety of directions, the resulting information can be reconstructed to generate three-dimensional information of an environment.
Rotating lasers require significant mechanical structure, increasing the complexity, size, and cost of the LIDAR device. Thus, solid state LIDAR systems have been developed in which a two dimensional array of VCSELS is used, with each individual VCSEL being aimed at a separate region of the three-dimensional environment. The solid state LIDAR systems are more robust, smaller in size, and less expensive than a rotating laser LIDAR system.
FIG. 1 shows an example of a VCSEL chip 10 that may include several individual VCSELs 12. FIG. 2 shows how VCSEL chips 10 may be conventionally arranged to achieve a two-dimensional VCSEL array. For example, rows of VCSELs can be formed by arranging VCSEL chips 10 end to end. A common cathode trace 22 may be provided for each row of VCSEL chips, connecting to an electrode on the rear side of each VCSEL in the row. Additionally, wirings 24 may be used to connect VCSELs in a columnar direction, with anode traces 20 being connected to each column of VCSELs.
However, in the structure of FIG. 2, the wirings 24 add complexity to the manufacturing process, thereby increasing cost. Also, using wirings 24 to connect one-dimensional arrays of VCSELs results in inefficient use of space and waste of VCSEL area.
Accordingly, it is desirable to provide a monolithic two-dimensional VCSEL array for use in a solid state LIDAR system in order to reduce manufacturing costs and make more efficient use of VCSEL space.