15 March 2013 Broadband quarter-wave plates at near-infrared using high-contrast gratings
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Proceedings Volume 8633, High Contrast Metastructures II; 86330O (2013) https://doi.org/10.1117/12.2009347
Event: SPIE OPTO, 2013, San Francisco, California, United States
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 ≃ π/2. As a result, a unity circular polarization conversion efficiency is achieved at λ0 = 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.
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Mehmet Mutlu, Mehmet Mutlu, Ahmet E. Akosman, Ahmet E. Akosman, Gokhan Kurt, Gokhan Kurt, Mutlu Gokkavas, Mutlu Gokkavas, Ekmel Ozbay, Ekmel Ozbay, } "Broadband quarter-wave plates at near-infrared using high-contrast gratings", Proc. SPIE 8633, High Contrast Metastructures II, 86330O (15 March 2013); doi: 10.1117/12.2009347; https://doi.org/10.1117/12.2009347
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