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Proceedings Paper

Output beam profile control of slow-light Bragg reflector waveguide deflector with high-contrast sub-wavelength grating
Author(s): Xiaodong Gu; Fumio Koyama
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Paper Abstract

We demonstrated a super-high resolution beam scanner based on a Bragg reflector waveguide. In this device, radiation profile is wavelength-dependent. However, for specific applications, it is important to optimize the radiation direction. We propose a solution for this by introducing a high-contrast sub-wavelength grating (HCG). Numerical simulations using finite-difference time-domain method (FDTD) and rigorous coupled wave analysis (RCWA) were carried out. We found that, by designing the thickness, period and duty cycle of HCG, the output phase and intensity can be changed. As a result, it is possible to shift the output direction of the beam profile. We discussed their dependences on HCG parameters. On the other hand, the thicknesses (numbers of pairs) of the top- and bottom- distributed Bragg reflectors (DBRs) mirrors are influential to the results. A discussion on the thickness dependence was carried out. We found that, HCG has stronger influence to thinner mirrors. Because HCG can provide high reflectivity, thin mirrors are not a problem in such slow-light waveguides. We believe this proposal can offer us a method to obtain desirable output beam direction of Bragg reflector waveguides deflectors.

Paper Details

Date Published: 19 February 2014
PDF: 6 pages
Proc. SPIE 8995, High Contrast Metastructures III, 89950S (19 February 2014); doi: 10.1117/12.2042059
Show Author Affiliations
Xiaodong Gu, Tokyo Institute of Technology (Japan)
Fumio Koyama, Tokyo Institute of Technology (Japan)

Published in SPIE Proceedings Vol. 8995:
High Contrast Metastructures III
Connie J. Chang-Hasnain; David Fattal; Fumio Koyama; Weimin Zhou, Editor(s)

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