A micro/nanofabrication feasible compact photonic crystal (PC) ring-resonator-based channel drop filter has been designed and analyzed for operation in C and L bands of communication window. The four-channel demultiplexer consists of ring resonators of holes in two-dimensional PC slab. The proposed assembly design of dense wavelength division multiplexing setup is shown to achieve optimal quality factor, without altering the lattice parameters or resonator size or inclusion of scattering holes. Transmission characteristics are analyzed using the three-dimensional finite-difference time-domain simulation approach. The radiation loss of the ring resonator was minimized by forced cancelation of radiation fields by fine-tuning the air holes inside the ring resonator. An average cross talk of −34 dB has been achieved between the adjacent channels maintaining an average quality factor of 5000. Demultiplexing is achieved by engineering only the air holes inside the ring, which makes it a simple and tolerant design from the fabrication perspective. Also, the device footprint of 500 μm2 on silicon on insulator platform makes it easy to fabricate the device using e-beam lithography technique.

Biosensing through bodily fluids, (especially through blood) is gaining attention due to their preciseness and broad range of detection. Various point-of-care diagnostic methods based on different sensing techniques are emerging rapidly. However, the future lies in simple and rapid detection technologies with a wide range of applications. Here we designed a sensor based on microwave Spoof Surface Plasmon Polaritons (SSPP) for sensing biological fluids. A novel octagon-shaped unit cell for the SSPP structure is fully explored in terms of its behavior and sensing capabilities. The SSPP microwave structure with a microfluidic reservoir is built as a multilayer arrangement based on the proposed unit cell to serve as a sensing platform for various bodily fluids.We first evaluated the sensing feature of the designed sensor using various sugar solutions. We further demonstrated the bio-sensing capacity of the sensor by testing the blood phantom samples which are prepared with different sugar concentrations. The sensor shows good sensitivity, and the corresponding sensing performance is experimentally validated with the distinguishable resonance frequency shift of 1.202 GHz on average per blood phantom sample. Our analysis revealed that this SSPP based sensor is a good candidate for biosensing of bodily fluids. This biosensing capability of the sensor may be further extended to other bodily fluids and thus offers non-destructive, non-invasive, label-free, rapid, and real-time biosensing.

This study investigates the use of spoof surface plasmon polaritons (SSPPs) as an effective feeding mechanism for antennas functioning within the extremely high-frequency (EHF) range. A novel method is proposed for feeding a dielectric rod antenna with SSPPs, featuring a simple design made from FR-4 material with a relative permittivity of 4.3. In contrast to traditional tapered dielectric rod antennas and their feeding configurations, this design shows promise for achieving a gain of up to 16.85 dBi with an antenna length of 7.6 λ₀. By carefully optimizing the design, impedance matching and directional radiation characteristics were obtained at 7.3 GHz. Simulations were conducted using CST Microwave Studio to validate and evaluate the design’s performance. The enhanced gain, improved impedance bandwidth, and use of cost-effective materials such as FR-4 present a compelling case for adopting this design in future wireless communication technologies. Additionally, the remote sensing properties of the feeder can be utilized for concealed object detection, material characterization, and the analysis of the spectral properties of materials.

A design is proposed to enhance the quality factor of a photonic crystal ring resonator. A super defect is employed inside the ring resonator, which consists of variation of hole dimensions inside the ring resonator in such a way that the radiation field components of the resonant nanocavity are forced to get cancelled in order to reduce radiation loss. After this forced cancellation, the improved $Q$ factor is calculated as 18,000. This photonic crystal ring resonator can be used for sensing applications like force sensing, pressure sensing, biochemical sensing, and communication applications like demultiplexing.

We explore the concept of spoof surface plasmon polaritons (SSPPs) as a means to confine plasmons on the surface of a tiny metallic structure. We focus on introducing an efficient transition design that confines the SSPP wave along a corrugated metallic strip with metal acting as a ground material. To achieve this, a unique unit cell specifically designed for waveguiding purposes was analyzed. The dispersion characteristics of this design were presented, demonstrating its potential for SSPP waveguiding applications. By varying the groove height from h1 to h7 (ranging from 0.5 to 3.5 mm), the SSPP waveguide was developed and analyzed its spectral characteristics through corresponding S parameters. Furthermore, the effects of altering the corrugated groove width from 1 to 2 mm was investigated. This variation is shown to have a linear impact on the gain, with a maximum gain of 7.71 dBi observed.