Broadband quarter-wave plates at near-infrared using high-contrast gratings
Author
Mutlu, M.
Akosman, A.E.
Kurt G.
Gokkavas, M.
Özbay, Ekmel
Date
2013Source Title
Proceedings of SPIE - The International Society for Optical Engineering
Print ISSN
0277786X
Volume
8633
Language
English
Type
ArticleItem Usage Stats
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Abstract
In this paper, we report the theoretical and experimental possibility of achieving a quarter-wave plate regime by using high-contrast gratings, which are binary, vertical, periodic, near-wavelength, and two-dimensional high refractive index gratings. Here, we investigate the characteristics of two distinct designs, the first one being composed of silicon-dioxide and silicon, and the second one being composed of silicon and sapphire. The suggested quarter-wave plate regime is achieved by the simultaneous optimization of the transverse electric and transverse magnetic transmission coefficients, TTE and TTM, respectively, and the phase difference between these transmission coefficients, such that |TTM| ≅ |TTE| and \TTM - \TTE ≅ -/2. As a result, a unity circular polarization conversion efficiency is achieved atλ0 = 1.55 μm for both designs. For the first design, we show the obtaining of unity conversion efficiency by using a theoretical approach, which is inspired by the periodic waveguide interpretation, and rigorous coupled-wave analysis (RCWA). For the second design, we demonstrate the unity conversion efficiency by using the results of finite-difference time-domain (FDTD) simulations. Furthermore, the FDTD simulations, where material dispersion is taken into account, suggest that an operation percent bandwidth of 51% can be achieved for the first design, where the experimental results for the second design yield a bandwidth of 33%. In this context, we define the operation regime as the wavelength band for which the circular conversion efficiency is larger than 0.9. © 2013 SPIE.
Keywords
High-contrast gratingPeriodic slab waveguide
Polarization
Quarter-wave plate
Finite-difference time-domain simulation
High-contrast gratings
Quarter wave-plate
Rigorous coupled wave analysis
Simultaneous optimization
Slab waveguides
Theoretical and experimental
Transmission coefficients
Bandwidth
Conversion efficiency
Design
Diffraction gratings
Finite difference time domain method
Polarization
Refractive index
Sapphire
Silicon
Truck trailers
Light polarization