Magneto-optical permittivity tensor spectra of undoped InSb, n-doped and p-doped InSb crystals were determined using the terahertz time-domain spectroscopy (THz-TDS) and the Fourier transform far-infrared spectroscopy (far-FTIR). A Huge polar magneto-optical (MO) Kerr-effect (up to 20 degrees in rotation) and a simultaneous plasmonic behavior observed at low magnetic field (0.4 T) and room temperature are promising for terahertz nonreciprocal applications. We demonstrate the possibility of adjusting the the spectral rage with huge MO by increase in n-doping of InSb. Spectral response is modeled using generalized magneto-optical Drude-Lorentz theory, giving us precise values of free carrier mobility, density and effective mass consistent with electric Hall effect measurement.

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In this paper, the ‘terahertz gap’ has been addressed by designing a novel THz metasurface for potential use in biosensing applications. The metasurface sensor employs Surface Plasmon Resonance (SPR). It operates in the 0 - 1 THz band. Two sharp reflection dips are provided by the sensor, which serve as indicators of analyte refractive index variations. Geometrical as well as compositional parameters of the biosensor design have been studied to optimize the performance in the targeted frequency band. The sensor design shows compatibility with different metals. The performance of the metasurface with gold, copper and aluminum has been investigated. The metasurface geometry is decently resilient to fabrication tolerances. The sensor maintains its resonance conditions when the angle of incidence is changed with minor deviations in the spectral response, but the polarization state of the incident terahertz beam clearly disturbs the absorption peak. Therefore, the sensing performance is restricted to a maximum allowable incidence angle of 20 degrees and circularly polarized terahertz beams. The resonance conditions for the metasurface appear around 0.4 and 0.7 THz. Both resonances have been investigated with respect to changes in the analyte refractive index. The chosen refractive index range is 1 to 1.5. The sensor response is calibrated by plotting the resonance frequency versus the refractive index. Least squares regression technique has been used to extract a data model for sensor response. Comparison of the proposed design with contemporary works has been incorporated into the paper. The sensor provides sensitivities of 0.1614 THz/ RIU and 0.23 THz/ RIU. The electromagnetic simulations have been carried out through the Finite Element Method (FEM).

We present a novel theoretical approach for analytically solving wave propagation through two-dimensional (2D) inhomogeneous slab waveguides. The validity and reliability of our analytical approach is verified by its application to electrical field distribution in 2D waveguides, when compared with numerically exact solution. The main advantage of this theoretical treatment is that the obtained solution is global and can be presented in an analytical form. The effects of the refractive index profile on the guided modes are analyzed by introducing the field distributions of the guided modes. Our analytical calculations show significant potential for use in various applications.

A robust fiber-optic interferometer, which is formed by introducing two bends (i.e. z shape) to the standard telecommunication single mode fiber, is designed and analyzed theoretically and experimentally for the refractive index (RI) sensing. The first (second) bend couples (re-couples) the core (cladding) mode to the cladding (core) modes. The RI-sensitive phase difference between the core and cladding modes gives rise to the modulation of the transmitted intensity. The experimental results show that the z-shaped interferometric sensor possesses an RI sensitivity as high as 196 nm/RIU and fit well with the theoretical predictions. An investigation of the effect of perturbations of bent angle reveals that the sensor possesses relative high sensitivities as the bent angle ranges from 13° to 17° with difference between the maximum and minimum sensitivities only 2.5% indicating the structure has a good fabrication tolerance to the inaccuracy of the bent angles. In addition, the sensor has advantages of low cost, simple structure and ease of fabrication, showing great potential in many sensing applications.

The theoretical background to calculate the effective index tuning using the ultrafast electro-optic Kerr effect and a design of slot waveguide geometry are presented. Analysis of the slot waveguide ring resonator with silicon nanocrystals as the active medium to implement the CMOS compatible electro-optic Kerr effect modulator indicates a modulation bandwidth of 51 GHz, therefore, allowing for 90 Gb/s data rate transmission, and a low energy consumption of 22.99 fJ/bit.