Implementing optical phased array beam steering with cascaded microlens arrays

Abstract

A cascade of microlens arrays that are decentered with respect to each other is one potential method for beam steering; the magnitude of the steering angle depends on the amount of decenter. A simpie argument is presented that shows that the output of such a system is analogous to the output of an optical phased may. The periodic nature of the exiting wavefront restricts allowed steering angles to values that are determined by the grating equation and the pitch of the microlens arrays. The efficiency of steering into a desired difi?action order of the phased array is determined by the amount of decenter of the microlens arrays, the coherence of the arrays, and the fill-factor at the output of the array. Maximum iill-factor is desired, which can be achieved through the addition of an intermediate microlens array that acts like a field lens. An experimental implementation of such a triplet cascade of microlens arrays, suitable for steering short wave i&ared laser light, is described. The extension of such a cascade to steering broad spectral band light is also discussed.

Nonmechanical Laser Beam Steering Based on Polymer Polarization Gratings: Design Optimization and Demonstration

“…Many nonmechanical steering techniques [3]- [11] have been studied, but all of these approaches are limited by one or more of the following reasons: low throughput, scattering, small steering angle/aperture, and large physical size/weight. Shi and coworkers have shown high efficiency nonmechanical steering utilizing a liquid crystal (LC) phase grating [12], but the technique was limited to small angles and slow speeds.…”

Novel laser beam steering techniques

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1-D Beam Steering with Fiber-type Optical Phased Array

“…In the past forty years, there has been much research on the material inducing phase shift, mostly on microlens array [1], liquid crystal [2,3] and waveguide [4,5]. However, the necessary mechanical movements limit the speed of beam steering of microlens array OPAs, while the restrained output power constrains the application of liquid crystal OPAs to some extent, and the difficulty in fabricating 2-D emitting array is a key disadvantage for waveguide type OPAs.…”