A Triband Metasurface Covering Visible, Midwave Infrared, and Long-Wave Infrared for Optical Security.

The independent manipulation of light across multiple wavelength bands provides new opportunities for optical security. Although dual-band optical encryption methods in the visible (VIS) and infrared bands have been developed, achieving synchronized and synergistic optical security across the VIS, midwave infrared (MWIR), and long-wave infrared (LWIR) bands remains a significant challenge. Here, we experimentally demonstrate a triband metasurface that covers the VIS, MWIR, and LWIR bands.

Ultra-compact scalable spectrometer with low power consumption.

An ultra-compact on-chip spectrometer was demonstrated based on an array of add-drop micro-donut resonators (MDRs). The filter array was thermally tuned by a single TiN microheater, enabling simultaneous spectral scanning across all physical channels. The MDR was designed to achieve large free spectral ranges with multimode waveguide bends and asymmetric coupling waveguides, covering a spectral range of 40 nm at the telecom waveband with five physical channels (which could be further expanded).

Reconfigurable multifrequency and wide-angle directional beaming of light from a subwavelength metal slit with graphene metasurfaces.

Directional beaming of light from a subwavelength slit surrounded with phase-gradient metasurfaces can be realized with very high efficiencies, but the available optical proposals suffer from narrow bandwidth after the fabrication process and cannot be reconfigured dynamically with switchable frequencies. Here we demonstrate reconfigurable multifrequency directional beaming by placing a graphene ribbon array at two sides of a subwavelength metallic slit. Each graphene ribbon works with the metallic film to fulfill the magnetic response, and the resultant reflection phase can cover full 0-2π range by changing the chemical potential of graphene.