A novel design of nearly perfect metamaterial absorber is proposed and analyzed for terahertz sensing applications. The full vectorial finite element method is used to simulate and analyze the reported design. The suggested structure is based on increasing the confinement of both electric and magnetic fields simultaneously at the resonance frequency. Therefore, an absorptivity of 0.99 is achieved at 2.249 THz with a narrow resonant peak and Q-factor of 22.05. The resonance frequency is sensitive to the surrounding medium refractive index at fixed analyte thickness. Consequently, the reported metamaterial design can be used as a refractive index (RI) sensor with high sensitivity of 300 GHz/RIU and figure of merit (FoM) of 2.94 through RI range from 1.0 to 1.39 at analyte thickness of 1.0 μm. Further, the proposed sensor has a sensitivity of 23.7 GHz/μm for the detection of the sensing layer thickness variation at fixed analyte RI of 1.35. It is worth noting that most of the biomedical samples have refractive index range from 1.3 to 1.39. Therefore, the reported sensor can be used for biomedical applications with high sensitivity.

A novel design of metamaterial biosensor for cancer early detection is proposed and analyzed. The suggested structure is based on two loops of hexagonal gold layers on a polyamide substrate. High field confinement is obtained in the sensing region with high absorption of 0.999 and high quality factor of 11.33 at f= 3.15 THz. The resonance frequency is sensitive to the sample refractive index variation. Therefore, high average sensitivity of 1649.8 GHz/RIU is achieved for cancer early detection through basal cell, breast cell, bervical cell, jurkat, MCF-7, and PC12. Further, high linear performance is obtained with good robustness against fabrication imperfection. The analysis is carried out using full vectorial finite element method.

We propose two novel designs of compact, linear, and all-optical OR and AND logic gates based on photonic crystal architecture. The proposed devices are formed by the combination of the ring cavities and Y-shape line defect coupler placed between two waveguides. The performance of the proposed logic gates has been analyzed and investigated using finite difference time domain method. The suggested design for AND gate offers ON to OFF logic level contrast ratio of not less than 6 dB and the suggested design for OR gate offers transmitted power of not less than 0.5. On top of that, the proposed OR and AND logic gates can operate at bit rates of around 0.5 and 0.208 Tb/s, respectively. Further, the calculated fabrication tolerances of the suggested devices show that the rods radii of the ring cavities need to be controlled with no more than ±10% and ±3% fabrication errors for optical OR and AND gates, respectively. It is expected that such designs have the potential to be key components for future photonic integrated circuits due to their simplicity and small size.

A novel ultra-high tunable photonic crystal fiber (PCF) polarization filter is proposed and analyzed using finite element method. The suggested design has a central hole infiltrated with a nematic liquid crystal (NLC) that offers high tunability with temperature and external electric field. Moreover, the PCF is selectively filled with metal wires into cladding air holes. Results show that the resonance losses and wavelengths are different in x and y polarized directions depending on the rotation angle φ of the NLC. The reported filter of compact device length 0.5 mm can achieve 600 dB / cm resonance losses at φ = 90° for x-polarized mode at communication wavelength of 1300 mm with low losses of 0.00751 dB / cm for y-polarized mode. However, resonance losses of 157.71 dB / cm at φ = 0° can be achieved for y-polarized mode at the same wavelength with low losses of 0.092 dB / cm for x-polarized mode.

A novel highly sensitive surface plasmon resonance-based liquid crystal (LC) photonic crystal fiber (PCF) temperature sensor is presented and studied. Through this letter, the coupling characteristics between the core guided mode inside the PCF core infiltrated with nematic LC and surface plasmon mode on the surface of nano gold wire are studied in detail. The structural geometrical parameters of the proposed design, such as number of metal rods, core diameter, and metal rod diameter are optimized to achieve highly temperature sensitivity. The suggested sensor of compact device length of 20 μm proved to surpass the recent sensors with high sensitivity of 10 nm/°C. The results are calculated using a full-vectorial finite-element method with irregular meshing capabilities and perfectly matched layer boundary conditions.