Surface-enhanced infrared absorption with Si-doped InAsSb/GaSb nano-antennas

Hexagonal-shaped graphene quantum plasmonic nano-antenna sensor

In this manuscript, a hexagonal-shaped graphene quantum plasmonic nanopatch antenna sensor is designed and investigated on silicon dioxide, zinc oxide and silicon substrates for quantum plasmonic biosensing applications. The optical properties of graphene are demonstrated using Kubo modeling to analyze the plasmon resonance characteristics of the nanopatch antenna. Nano-circuit modeling of the hexagonal-shaped graphene nano-antenna is proposed and validated using CST simulations. The parametric analysis of the hexagonal-shaped nanopatch antenna is performed using design parameters such as R (radius of the hexagon), Tp (thickness of the hexagon) and µc (chemical potential of graphene) to obtain optimum characteristics suitable for quantum plasmonic sensing applications. The study demonstrates that the proposed hexagonal-shaped nano-antenna exhibits gain of 4.9 dBi, 2.46 dBi, 14.99 dBi, 8.25 dBi, 5.15 dBi, 10.87 dBi and 2.4 dBi at 29.87 THz, 30 THz, 35 THz, 113.5 THz, 132.5 THz, 85 THz and 24 THz, respectively. The field enhancement factors observed at these frequencies are 794, 779, 584, 255, 234, 654 and 217, respectively.

Surface-Enhanced IR-Absorption Microscopy of Staphylococcus aureus Bacteria on Bactericidal Nanostructured Si Surfaces

Surface-enhanced IR absorption (SEIRA) microscopy was used to reveal main chemical and physical interactions between Staphylococcus aureus bacteria and different laser-nanostructured bactericidal Si surfaces via simultaneous chemical enhancement of the corresponding IR-absorption in the intact functional chemical groups. A cleaner, less passivated surface of Si nanoripples, laser-patterned in water, exhibits much stronger enhancement of SEIRA signals compared to the bare Si wafer, the surface coating of oxidized Si nanoparticles and oxidized/carbonized Si (nano) ripples, laser-patterned in air and water. Additional very strong bands emerge in the SEIRA spectra on the clean Si nanoripples, indicating the potential chemical modifications in the bacterial membrane and nucleic acids during the bactericidal effect.

Modeling of second harmonic generation in hole-doped silicon-germanium quantum wells for mid-infrared sensing

The development of Ge and SiGe chemical vapor deposition techniques on silicon wafers has enabled the integration of multi-quantum well structures in silicon photonics chips for nonlinear optics with potential applications to integrated nonlinear optics, however research has focused up to now on undoped quantum wells and interband optical excitations. In this work, we present model calculations for the giant nonlinear coefficients provided by intersubband transitions in hole-doped Ge/SiGe and Si/SiGe multi-quantum wells. We employ a valence band-structure model for Si_1-xGe_x to calculate the confined hole states of asymmetric-coupled quantum wells for second-harmonic generation in the mid-infrared. We calculate the nonlinear emission spectra from the second-order susceptibility tensor, including the particular vertical emission spectra of valence-band quantum wells. Two possible nonlinear mid-infrared sensor architectures, one based on waveguides and another based on metasurfaces, are described as perspective application.