JNP thanks the reviewers who served the journal in 2024.

Polarization beam splitters (PBSs) have received increasing attention due to their unique ability to split or combine two orthogonal linear polarization modes. We propose a compact all-fiber photonic crystal fiber-based terahertz (THz) PBS with a twin butterfly core. The design and optimization of the device are performed using the finite difference time domain method in combination with perfected matching layer boundary conditions. The influences of the PBS’s structural parameters on its coupling length as well as coupling length ratio are examined. The findings reveal that at 1 THz, the maximum polarization extinction ratio is 78.5 and 52.5 dB for x- and y-polarization lights, respectively, and it has an operation bandwidth of 24 GHz. The length of the PBS is merely 25.1 mm. Due to its remarkable characteristics and outstanding compatibility with the current THz optical fiber information system, the device will be widely applied in future THz radar, remote sensing, environmental monitoring, and imaging systems.

Artificial chiral structure plays an important role in the realization of strong chiroptical response and flexible light manipulation. Without introducing intrinsic chiral metamaterial with a complicated structure, we utilize a chiral metasurface to achieve giant extrinsic and tunable terahertz (THz) chirality assisted by quasi-bound states in the continuum (qBIC). The giant extrinsic chirality in this work originates from the mirror symmetry breaking of the proposed plasmonic THz metasurface; owing to the optical properties of InSb, the chirality induced by this metasurface can be actively manipulated by tailoring the angle of the elliptical nanopillar pairs and temperature. This proposed THz qBIC-assisted metasurface opens a new door for the detection of strong chirality, which may find potential important applications in THz science and technology, such as THz spin optics, chiral sensing, and efficient chiral light-emitting devices.

Although black phosphorous (BP) is a promising two-dimensional material for next-generation infrared (IR) photodetectors, enhancing its quantum efficiency remains challenging. We propose a hybrid BP/plasmonic nanograting with a narrow width and a high-depth groove system to address this challenge. The absorption properties of BP formed on plasmonic nanograting systems with two configurations, namely, an armchair edge normal and parallel to the groove direction, were numerically investigated. These systems demonstrated polarization-selective, wide-angle, near-unity absorption in the IR-wavelength region, and the absorption wavelength was controlled primarily by the groove depth. The BP induced a blue shift of the absorption wavelength, and the wavelength shift was larger for the armchair edge that was normal to the groove direction than that parallel to the groove direction. These results can be attributed to the coupling between the anisotropic surface plasmon resonances of BP and the plasmonic nanogratings. Moreover, this wavelength shift was enhanced by an increase in the carrier density of BP. The BP carrier density can be controlled by its electrical gating. This implies that the detection wavelength can be controlled by electrical gating of the BP. These systems can contribute to the development of high-performance BP-based polarization-selective and/or wavelength-tunable advanced IR photodetectors.