We present a simple dual band absorber design and investigate it in the terahertz (THz) region. The proposed absorber works in dual operating bands at 5.1 THz and 11.7 THz. By adjusting the graphene chemical potential, the proposed absorber has the controllability of the resonance frequency to have perfect absorption at various frequencies. The graphene surface plasmon resonance results in sharp and narrow resonance absorption peaks. For incident angles up to 8°, the structure possesses near-unity absorption. The proposed sensor absorber’s functionality is evaluated using sensing medium with various refractive indices. The proposed sensor is simulated for glucose detection and a maximum sensitivity of 4.72 THz/RIU is observed. It has a maximum figure of merit (FOM) and Quality factor (Q) value of 14 and 32.49, respectively. The proposed optimal absorber can be used to identify malaria virus and cancer cells in blood. Hence, the proposed plasmonic sensor is a serious contender for biomedical uses in the diagnosis of bacterial infections, cancer, malaria, and other diseases.

A photonic crystal (PhC) based optical component paves a path to the upcoming all-optical computer processors. All the components can be realized with the help of PhCs. In particular, optical gates have played a major part in the development of all-optical half adders which has lead to the bloom of optical computing technology. In this paper, a PhC based optical half adder is proposed and a brief analysis is carried out for the different crystal structures and lattice patterns. The efficiency of the device is analyzed by providing proper distinct space in output power between logical ‘0’ and ‘1’ states and it operates well even in the reduced input power level. The error can be minimized while identifying the logical states (logic ‘0’ and logic ‘1’), by setting a threshold limit for output power. The threshold level is fixed such that if it is greater than 0.7 µ W, it is considered as logic ‘1’, and if it is less than 0.35 µ W, then it will be taken as logic ‘0’. The device with circular crystals in a hexagonal lattice provides a better contrast ratio of 12.55 dB and 9.29 dB for ‘sum’ and ‘carry’ respectively. The miniature size of the proposed device depicts that this device is compatible with photonic integrated circuit (PIC) applications.

The design and characterisation of a novel dual-band implantable antenna with compact size is presented in this research. The antenna, which is $$5 \times 5 \times 0.635 {\text{mm}}^{3}$$ in size and operates at two critical frequencies—0.954 GHz in the UHF band and 2.4 GHz in the ISM band—was fabricated on an RT6010 substrate. The U-shaped slot and shorting pin on the radiating element have been exploited to achieved dual-band and circular polarization. The antenna is noteworthy for achieving circular polarization with a broad axial ratio bandwidth of 24.6%, which enables strong performance throughout its operating frequencies. The proposed antennas SAR values satisfy IEEE safety standards for implantable medical devices with a gain of − 28.1 dB at 2.4 GHz and − 31.2 dB at 0.954 GHz, despite its small size. The design represents a significant advancement in the field of medical implant technology since it prioritizes effective wireless communication capabilities while upholding strict safety regulations.