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1 July 1997 Waveguide-grating couplers for illumination of photonic antennas
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To obtain uniform illumination of photonic reconfigurable antennas, a waveguide grating with a nonuniform grating profile may be used. Theoretical studies using approximate models indicate that the grating profile should have a hyperbolic spatial variation along the length of the coupler. This yields a spatially varying diffraction efficiency that compensates for the loss of light as it is diffracted out of the waveguide. Utilizing a holographic interferometer with a computer controlled shutter in one arm, gratings with appropriate spatial profile variation have been recorded in photoresist and transferred to produce photopolymer waveguide gratings. These planar couplers are integrated with optical fiber bundles for input light delivery. The grating periods are chosen to produce orthogonally propagating output waves. A dielectric mirror arrangement is used to reflect the parasitic diffracted order back onto the antenna element. The best devices obtained to date exhibit output uniformity of plus or minus 6% over a coupler length of 20 mm with total efficiency exceeding 50%.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Robert Magnusson, Zhongshan Liu, Debra D. Wawro, Preston P. Young, and DongHo Shin "Waveguide-grating couplers for illumination of photonic antennas", Proc. SPIE 3075, Photonic Processing Technology and Applications, (1 July 1997);

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