Design of diffractive optical elements array with wide field of view for integration with photodetectors

Abstract

A special design is proposed to achieve a diffractive optical elements (DOEs) array with wide field of view (WFOV), which integrates with InGaAs/InP p–i–n photodetectors array on the rear surface. It consists of five different DOEs that focus the light from different angles into the corresponding photodetectors. Each DOE will take care of one dedicated direction of the incident light. Consequently, a WFOV of 120° can be obtained. This will increase the detection efficiency of the photodetector array. At the same time, we can also determine the direction of the incident light by probing each photodetector elements response. The structure and parameters of the designed DOEs array have been evaluated. The optimum surface-relief equation of each DOE, which describes an aspheric surface profile, has been obtained. Simulation results of their performance will be presented in this paper. Combining with these efforts, the optimum parameters for fabricating the designed DOE array by direct laser writing are also described.