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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.

Biomarkers are the primary indicators of human health. Measurements traditionally rely on targeted binding and assays, which, in turn, rely on specific “labels” that define the biomarker or molecule of interest. While selective and specific, label‐based approaches limit the range of biomarkers a technology can detect. Technologies that can detect and analyze a broad range of biomarkers offer versatility, especially rapid repurposing for new targets. Optical technologies for label‐free biomarker sensing enable noninvasive, minimal‐contact, and wearable or point‐of‐care rapid diagnostic measurements. Herein, label‐free biomarker detection is reviewed with an emphasis on progress toward miniaturized and noninvasive wearable devices. Compact light‐emitting devices and optical detection technologies are presented, tailored for a large range of biomarkers, including recent advances in battery‐free devices. Label‐free detection is reusable, reagent‐free, and allows continuous long‐term monitoring. The potential for optical technologies for label‐free detection in terms of integration, device design, and future applications is summarized.

A photonic crystal ring resonator‐based 6 × 6 router has been designed and reported. The router is designed using silicon pillars with a refractive index of 3.47 perforated in the air background of refractive index 1 in a square lattice with a lattice constant of a = 562 nm. The router is designed to operate in the third optical window wavelength which has low loss and most widely used in optical communication systems and networks. Plane‐wave expansion and finite difference time domain method has been used to obtain the bandgap and performance of the designed router, which exhibits acceptable performance such as low insertion loss, low propagation delay, and low crosstalk. These routers will find applications in the photonic integrated circuit that paves a path to all‐optical networks.

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