Search

One attractive option to achieve real-time terahertz (THz) imaging is a microelectromechanical systems (MEMS) bimaterial sensor with embedded metamaterial absorbers. We have demonstrated that metamaterial films can be designed using standard MEMS materials such as silicon oxide (SiOx), silicon oxinitrate (SiOxNy), and aluminum (Al) to achieve nearly 100% resonant absorption matched to the illumination source, providing structural support, desired thermomechanical properties and access to external optical readout. The metamaterial structure absorbs the incident THz radiation and transfers the heat to bimaterial microcantilevers that are connected to the substrate, which acts as a heat sink via thermal insulating legs, allowing the overall structure to deform proportionally to the absorbed power. The amount of deformation can be probed by measuring the displacement of a laser beam reflected from the sensor's metallic ground plane. Several sensor configurations have been designed, fabricated, and characterized to optimize responsivity and speed of operation and to minimize structural residual stress. Measured responsivity values as high as 1.2 deg /µW and time constants as low as 20ms with detectable power on the order of 10 nW were obtained, indicating that the THz MEMS sensors have a great potential for real-time imaging. [ABSTRACT FROM AUTHOR]

We design a photonic crystal fiber (PCF) biosensor, based on the refractive index, capable of operating in terahertz (THz) region. This structure comprises a dual steering wheel (DSW) shape of large noncircular air–hole structure in the cladding region. This PCF is designed using rectangular structured air holes in core, and they are filled with blood components as analytes. We use the full-vectorial finite-element method to optimize the structural parameters and to characterize the proposed PCF. The simulation results demonstrate a high relative sensitivity for water, cytop, plasma, white blood cells, hemoglobin, red blood cells, sylgard184, biotin–streptavidin, polyacrylamide, and bovine serum albumin. As the practical sensor setup requires connecting a single-mode fiber with that of the PCF, we compute the effective area (Aeff), V-parameter (Veff), spot size (Weff), beam divergence (θ), and dispersion (β2) of the proposed PCF over the wide THz range. We envisage that the proposed fiber may not only be useful for the measurement of various blood components but also for polarization-preserving applications in the THz region. [ABSTRACT FROM AUTHOR]