scholarly journals Continuous angle-tunable birefringence with freeform metasurfaces for arbitrary polarization conversion

2020 ◽  
Vol 6 (23) ◽  
pp. eaba3367 ◽  
Author(s):  
Zhujun Shi ◽  
Alexander Y. Zhu ◽  
Zhaoyi Li ◽  
Yao-Wei Huang ◽  
Wei Ting Chen ◽  
...  
Keyword(s):  
Quantum Optics ◽  
Optical Anisotropy ◽  
Unique Feature ◽  
Refractive Indices ◽  
Linear Birefringence ◽  
Polarization Conversion ◽  
Angle Of Incidence ◽  
Bulk Crystals ◽  
Polarization Imaging ◽  
Polarization Optics

Birefringence occurs when light with different polarizations sees different refractive indices during propagation. It plays an important role in optics and has enabled essential polarization elements such as wave plates. In bulk crystals, it is typically constrained to linear birefringence. In metamaterials with freeform meta-atoms, however, one can engineer the optical anisotropy such that light sees different indices for arbitrary—linear, circular, or elliptical—orthogonal eigen-polarization states. Using topology-optimized metasurfaces, we demonstrate this arbitrary birefringence. It has the unique feature that it can be continuously tuned from linear to elliptical birefringence, by changing the angle of incidence. In this way, a single metasurface can operate as many wave plates in parallel, implementing different polarization transformations. Angle-tunable arbitrary birefringence expands the scope of polarization optics, enables compact and versatile polarization operations that would otherwise require cascading multiple elements, and may find applications in polarization imaging, quantum optics, and other areas.

Optical properties of a liquid crystal with small ordinary and extraordinary refractive indices and small optical anisotropy

2014 ◽  
Vol 22 (3) ◽  
Author(s):  
J. Kędzierski ◽  
K. Garbat ◽  
Z. Raszewski ◽  
M. Kojdecki ◽  
K. Kowiorski ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Liquid Crystal ◽  
Optical Anisotropy ◽  
Order Parameter ◽  
Orientational Order ◽  
Refractive Indices ◽  
Orientational Order Parameter ◽  
Unknown Density ◽  
Abbe Refractometer

AbstractOptical properties of a nematic liquid crystal with small refractive index and small birefringence were studied. The ordinary and extraordinary refractive indices and birefringence were measured as functions of temperature by using an Abbe refractometer and wedge nematic cells. From values of these indices the nematic orientational order parameter was calculated by using several methods and corresponding mathematical models. Kuczyński et al. method was found to be suitable for determining the order parameter also for materials featuring small ordinary refractive index, with unknown density.

Optical Properties of II-IV-N2 Semiconductors

2004 ◽  
Vol 831 ◽  
Author(s):  
John Muth ◽  
Ailing Cai ◽  
Andrei Osinsky ◽  
Henry Everitt ◽  
Ben Cook ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Optical Loss ◽  
Wide Band ◽  
Refractive Indices ◽  
Bulk Crystals ◽  
Wide Band Gap ◽  
Optical Effects ◽  
Transmission Studies ◽  
Novel Devices

ABSTRACTRecently, wide band gap II-IV-N2 semiconductors such as ZnSiN2, and ZnGeN2 and ZnSiGeN2 have been synthesized, but very little is known about their band structure, optical properties, or electronic properties. Bulk crystals are hard to synthesize because high temperatures and pressures are required. The success in growing II-IV-N2 films epitaxially by MOCVD creates interesting opportunities. The crystal structure of II-IV-N2 compounds is orthorhombic, and when grown on r-plane sapphire can provide a suitable template for GaN growth. Optical transmission studies of the band edge of ZnSiN2 and ZnSiGeN2 with varying Si and Ge percentages were conducted. The indirect nature of the band gap was investigated, and prism coupling was used to obtain the refractive indices in the visible and NIR portion of the spectrum. Although the crystal symmetry was orthorhombic, the refractive indices indicated uniaxial optical properties. Optical loss measurements indicate that the films are suitable for waveguides and novel devices based on birefringent optical effects.

scholarly journals Tuning the optical isotropic point of mixed crystals of ethylenediammonium sulfate/selenate

2020 ◽  
Vol 53 (1) ◽  
pp. 51-57
Author(s):  
Melissa Tan ◽  
Alexander T. Martin ◽  
Alexander G. Shtukenberg ◽  
Bart Kahr
Keyword(s):  
Solid Solution ◽  
Single Crystal ◽  
Mueller Matrix ◽  
Mixed Crystals ◽  
Refractive Indices ◽  
Linear Birefringence ◽  
Solid Solution Series ◽  
X Ray Diffraction ◽  
X Ray ◽  
Isotropic Point

In anisotropic crystals, optical isotropic points are wavelengths where linear birefringence disappears because the refractive indices for both eigenmodes are accidentally equivalent. Here, the optical isotropic point of ethylenediammonium selenate (EDSe) is tuned by generating a solid-solution series of EDSe doped with sulfate. Mueller matrix polarimetry and single-crystal X-ray diffraction are used to correlate changes in linear birefringence with the crystal composition of EDS x Se1−x . A scheme for using mixed crystals with isotropic points as tunable birefringent optical bandpass filters is proposed and their performance is modeled.

Complex Refractive Index Determination of Bulk Materials from Infrared Reflection Spectra

1995 ◽  
Vol 49 (5) ◽  
pp. 639-644 ◽  
Author(s):  
Kiyoshi Yamamoto ◽  
Akio Masui
Keyword(s):  
Refractive Index ◽  
Prior Information ◽  
Complex Refractive Index ◽  
Refractive Indices ◽  
Angle Of Incidence ◽  
Reflection Spectra ◽  
Bulk Materials ◽  
Infrared Reflection ◽  
Normal Angle

Kramers-Kronig analysis is applied to extract complex refractive indices of an isotropic single crystal, ceramics, glasses, and organic materials from their infrared external reflection spectra measured near the normal angle of incidence. It is demonstrated that this technique is versatile and can obtain complex refractive indices of materials. The great advantage of this technique is that a wide variety of materials (organic to inorganic, solid to liquid) can be analyzed and that no prior information is required for the analysis. The calculation procedure of the principal integration in Kramers–Kronig analysis of reflection spectra is also presented.

Matrix Fourier optics enables a compact full-Stokes polarization camera

Science ◽  
2019 ◽  
Vol 365 (6448) ◽  
pp. eaax1839 ◽  
Author(s):  
Noah A. Rubin ◽  
Gabriele D’Aversa ◽  
Paul Chevalier ◽  
Zhujun Shi ◽  
Wei Ting Chen ◽  
...  
Keyword(s):  
Fourier Optics ◽  
Single Shot ◽  
Practical Realization ◽  
Optical Elements ◽  
Polarization Imaging ◽  
Parallel Polarization ◽  
Polarization Optics ◽  
Recent Developments ◽  
Polarization Of Light ◽  
Polarization Camera

Recent developments have enabled the practical realization of optical elements in which the polarization of light may vary spatially. We present an extension of Fourier optics—matrix Fourier optics—for understanding these devices and apply it to the design and realization of metasurface gratings implementing arbitrary, parallel polarization analysis. We show how these gratings enable a compact, full-Stokes polarization camera without standard polarization optics. Our single-shot polarization camera requires no moving parts, specially patterned pixels, or conventional polarization optics and may enable the widespread adoption of polarization imaging in machine vision, remote sensing, and other areas.

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