Omnidirectional polarization beam splitter for white light

Omnidirectional broadband phase modulation by total internal reflection

Phase modulation plays a crucial role in shaping optical fields and physical optics. However, traditional phase modulation techniques are highly dependent on angles and wavelengths, limiting their applicability in smart optical systems. Here, we propose a first-principle theory for achieving constant phase modulation independent of incident angle and wavelength. By utilizing a hyperbolic metamaterial and engineering-specific optical parameters, different reflective phase jumps are achieved and tailored for both transverse electric (TE) and transverse magnetic (TM) waves. The aimed reflection phase difference between TE and TM waves can be thus achieved omnidirectionally and achromatically. As an example, we propose a perfect omnidirectional broadband reflection quarter wave plate. This work provides fundamental insights into manipulating optical phases through optical parameter engineering.

Designing a wideband dielectric polygonal directional beam antenna using the ray inserting method

This paper presents the design of a wideband polygonal directional beam antenna based on the ray inserting method. The wideband characteristic of the directional beam antenna is achieved thanks to the use of inhomogeneous dielectric material. Also, unlike most previous works, the present design can be implemented with the isotropic and above unity refractive index materials, consequently simplifying its fabrication process. The finite difference time domain scheme is used to evaluate the directional beam antenna.

Omnidirectional and compact transmissive chromatic polarizers based on a dielectric-metal-dielectric structure

High-performance omnidirectional transmissive chromatic polarizers based on a one-dimensional dielectric-metal-dielectric subwavelength grating structure are proposed. The incident angle-insensitive properties, azimuthal angle-insensitive properties and polarization features are investigated thoroughly to realize the proposed omnidirectional transmissive chromatic polarizers. The color difference at different angles for the proposed yellow polarizers is less than 0.9746, and the extinction ratio at different angles for the proposed cyan polarizers exceeds 26. Analysis of the power density profiles for the transverse electric (TE) and transverse magnetic (TM) polarizations show that surface plasmon resonance and high refractive index contrast properties lead to excellent polarization features and high angular tolerance.

Polarization beam splitter based on extremely anisotropic black phosphorus ribbons

Properly designed black phosphorus (BP) ribbons exhibit extreme anisotropic properties, which can be used to fabricate a high-efficiency transmitter or reflector depending on the linear polarization of excitation. In this study, we design a highly efficient and broad-angle polarization beam splitter (PBS) based on extremely anisotropic BP ribbons around the mid-infrared frequency region with an ultra-thin structure, and study its performance by using transfer matrix calculation and finite element simulation. In the broad frequency range of 80.4 terahertz - 85.0 terahertz (THz) and an wide angle range of more than 50°, the reflectivity and transmissivity of the designed PBS are both larger than 80% and the polarization extinction ratios are higher than 25.50 dB for s-polarization light and 20.40 dB for p- polarization light, respectively. Furthermore, the effect of incident angle and device parameters on the behavior of the proposed PBS is examined. Finally, we show that the operation frequency of this PBS can be tuned by the electron concentration of BP, which can facilitate some practical applications such as tunable polarization splitters or filters, and mid-infrared sensors.

Ultra-Thin Metamaterial Beam Splitters

Here, we present blueprints for three types of ultra-thin beam splitters based on versatile fishnet metamaterial structures at the 1.55 μ m optical communication wavelength. The thicknesses of the designed polarizing beam splitter and partially polarizing beam splitter are 1/26 of the free-space wavelength, while the thickness of the non-polarizing beam splitter is 1/13 of the free-space wavelength. Numerical simulations show that, compared to other miniaturization approaches including popular dielectric metasurfaces, metal-based metamaterial approach can provide much thinner beam splitters with reasonable performance. Such beam splitters can enable miniaturization of conventional and advanced quantum photonic systems towards higher density, scalability, and functionality.