Broadband and Incident-Angle-Modulation Near-Infrared Polarizers Based on Optically Anisotropic SnSe

Abstract

Optical anisotropy offers an extra degree of freedom to dynamically and reversibly regulate polarizing optical components, such as polarizers, without extra energy consumption and with high modulating efficiency. In this paper, we theoretically and numerically design broadband and incident-angle-modulation near-infrared polarizers, based on the SnSe, whose optical anisotropy is quantitatively evaluated by the complete dielectric tensor, complex refractive index tensor, and derived birefringence (~|Δn|max = 0.4) and dichroism (~|Δk|max = 0.4). The bandwidth of a broadband polarizer is 324 nm, from 1262 nm to 1586 nm, with an average extinction ratio above 23 dB. For the incident-angle-modulation near-infrared polarizer, the high incident angles dynamically and reversibly modulate its working wavelength with a maximum extinction ratio of 71 dB. Numerical simulations and theoretical calculations reveal that the considerable absorption for p light and continuously and relatively low absorption of s light lead to the broadband polarizer, while the incident-angle-modulation one mainly arises from the blue shift of corresponding wavelength of p light’s minimum reflectance. The proposed novel design of polarizers based on SnSe are likely to be mass-produced and integrated into an on-chip system, which opens up a new thought to design polarizing optical components by utilizing other low-symmetry materials.

Wavelength‐Linearly‐Dependent and Polarization‐Sensitive Perfect Absorbers based on Optically Anisotropic Germanium Selenide (GeSe)

“…As a lossless dielectric material, the SiO 2 layer adds an extra degree of freedom to regulate the destructive interference effect by altering its thickness ($${{d}_{{\mathrm{Si}}{{{\mathrm{O}}}_2}}}$$) in addition to that of GeSe ( d GeSe ). [ 33 ] Furthermore, the Si substrate was selected because it is compatible with integrated optoelectronics and on‐chip systems. [ 32a ] Since the Si substrate may not allow the transmission of incident light ( T = 0), the absorbance of s‐ or p‐light ( Abs s or Abs p ) is accordingly calculated by the corresponding reflectance R j ( j = s or p).…”

“…According to our design thoughts and device principles, such novel low‐symmetry materials must simultaneously realize destructive interference (and then perfect absorption at their appropriate thickness) and the separation of the operating wavelength of the perfect absorber. Therefore, both weak‐absorption low‐symmetry materials with giant birefringence Δ n (such as the experimentally reported BP, [ 29 ] SnSe, [ 33 ] and α‐MoO 3 [ 36 ] ) and lossless low‐symmetry materials with giant birefringence Δ n (also known as high‐performance, well‐designed birefringent materials [ 37 ] ) are probably the two appropriate options.…”

Can 2D Semiconductors Be Game-Changers for Nanoelectronics and Photonics?

“…(b) Absorption coefficients and (c) loss tangent for selected materials, including Si, GaAs, MAPbI 3 perovskite, and TMDs. All the figures are reproduced with permission from from ref with additional modifications from refs , , and . Copyright 2017 American Chemical Society.…”

“…Apart from TMDs, members of the metal monochalcogenide family, such as SnSe, also exhibit promising photovoltaic (PV) figures of merit. SnSe possesses a small bandgap (∼1 eV in bulk, 1.3 eV in monolayer) and a high absorption coefficient (refer to Figure b), making it an exciting material for broadband absorption. Consequently, SnSe has been under exploration for solar cell applications for the past three decades .…”