In this work, we propose and analyze a thermally tunable metasurface based on indium antimonide (InSb), designed to operate in the terahertz (THz) frequency range. The metasurface exhibits dual functionalities: single-band perfect absorption and efficient polarization conversion, enabled by the temperature-dependent permittivity of InSb. At approximately 280 K, InSb transitions into a metallic state, enabling the metasurface to achieve near-unity absorptance (100%) at 0.408 THz under normal incidence, independent of polarization. Conversely, when InSb behaves as a dielectric at 200 K, the metasurface operates as an efficient polarization converter. By exploiting structural anisotropy, it achieves a polarization conversion ratio exceeding 85% over the frequency range from 0.56 to 0.93 THz, while maintaining stable performance for incident angles up to 45°. Parametric analyses show that the resonance frequency and absorption intensity can be effectively tuned by varying the InSb square size and the silica (SiO₂) layer thickness, achieving maximum absorptance at a SiO₂ thickness of 16 μm. The proposed tunable metasurface offers significant potential for applications in THz sensing, imaging, filtering, and wavefront engineering.

Low loss optical interconnects in hybrid integrated platforms for silicon photonics are likely to become increasingly important to overcome power consumption limitations in telecom packaging applications. Here, we show a short taper device that effectively interconnects electro-optic polymer modulator waveguides and silicon-on-insulator platforms without altering the polymer modulator fabrication process. We achieved power transmission better than -0.2 dB with very good alignment shift tolerance over the whole C-band, by using tapers as short as 179.5 micrometers.

The design of passive photonic devices based on geometry optimization can lead to energy-efficient, small-footprint, and fabrication-ready geometries. In this work, we propose an angle-based parametrization method to optimize Y-junction splitters based on multimode interferometers. The selected figure of merit was the transmittance in the SCL and OESCL optical fiber communication bands. The performances of three optimization methods were compared: (i) particle swarm optimization (PSO), (ii) genetic algorithm (GA), and (iii) the covariance matrix adaptation-evolution strategy (CMA-ES). The results show that CMA-ES parametrization produces similar transmittance results (≤1.5% of difference) to PSO in the first 40 generations. The CMA-ES results are identical in the SCL (1460–1625 nm) and OESCL (1260–1625 nm) bands, whereas the GA and PSO executions are slightly different in terms of the rate and similarity of the figure of merit.

Through numerical simulations, we have demonstrated the electrical tunability of a silicon–organic metasurface that may be useful for optical-communication systems with wavelength-division multiplexing. We began with a nonintuitive geometry and performed topological optimization of a meta-atom comprising a 20×20-variable silicon-on-insulator grid, with electrical tunability arising from a stable electro-optic polymer named JRD1. The controlling electric potential was taken to be applied via two electrodes made of indium-doped tin oxide. A tunability rate of 0.55 nm V−1 in the optical-communication E and S bands was predicted, with the inter-channel crosstalk between adjacent channels ranging from 6 to 14 dB for 45 deg angle of incidence. The proposed metasurface should perform robustly with respect to the variation of the angle of incidence.

A pixelation approach was adopted to design an all-dielectric periodic structure without bidirectional symmetry in the thickness direction to exhibit asymmetric electromagnetic transmission (AET) at near-infrared wavelengths ranging from 1.2 to 1.8 µm. Whereas some pixels represent a dielectric solid, others represent a transparent electro-optic polymer with a high electro-optic coefficient. This structure can demonstrate AET as high as 0.90. A specific combination of an applied voltage and the angle of incidence will lead to an acceptable AET magnitude for a particular wavelength, which is promising for electro-optically and orientationally programmable optical diodes in in-line optical systems. The use of a transparent electro-optic polymer with a high electro-optic coefficient enables sub-nanosecond switching speeds desirable for optical communications.