High-Throughput Continuous Beam Steering Using Rotating Polarization Gratings |
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Authors: | Oh C Kim J Muth J Serati S Escuti M J |
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Affiliation: | Dept. of Electrical and Computer Engineering, North Carolina State University, Raleigh,; |
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Abstract: | A new beam steering concept comprising independently rotating, inline polarization gratings (PGs) is experimentally demonstrated. The approach, which we term Risley gratings, achieves high steering throughput within a large field-of-regard (FOR) in a fashion similar to Risley prisms, composed of wedged prisms. However, because PGs are patterned in thin liquid crystal layers, they enable a system with far less thickness, weight, and beam walk-off. Furthermore, large apertures are feasible and wavelengths from visible to infrared can be chosen. Any direction within a solid angle defined by twice the diffraction angle of each PG can be addressed mechanically. Here we demonstrate a Risley grating system with a 62 $^{circ}$ FOR and 89%–92% transmittance at 1550-nm wavelength, using two PGs with 6- $muhbox{m}$ grating period. |
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