This PDF file contains the front matter associated with SPIE Proceedings Volume 12774, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

The current research proposes the development of a plasmonic elliptical ring resonator structure with a Metal (Ag) Insulator Metal (Ag) waveguide configuration for the purpose of bio sensing. The research involves a distinctive exploration of the sensitivity and peak resonance wavelength, which are found to be varied by altering the aspect ratio of the elliptical ring resonator. The results reveal a marked increase in sensitivity, ranging from 732.60 nm/RIU to 1113.70nm/RIU, by changing the aspect ratio (ratio of major to minor radius of elliptical ring resonator) from 1.61 to 3.72. Furthermore, these adjustments produce a noticeable redshift in the peak resonance wavelength, as the aspect ratio increases. The study also highlights the impact of other geometrical factors of the sensor on its sensing characteristics. It is found that sensitivity changes significantly with the change in width of resonator and linear waveguide, and it is found to be decreased when width increases. The results of variation in width of waveguides reveals that there occurs a red shift in resonance wavelength when width decrease and vice versa. Based on the finding of all significant geometrical factors an optimized structure is selected with the optimum value of sensitivity. Which evidences its suitability for biosensing purpose and with its superior capabilities, the sensor can play a crucial role in distinguishing between healthy and cancerous cell and will be helpful in detecting cancer at early stage. The investigation and observations involved in the process are computed numerically using the finite difference in time domain method (FDTD).

This study demonstrates the possibility of the surface enhanced Raman spectroscopy (SERS) method to determine concentrations of methotrexate (MTX) in human plasma. This method makes it possible to detect low concentrations of methotrexate in biological samples with relatively inexpensive portable equipment. The SERS signal may be greatly enhanced using nanostructured plasmonic materials which will make this method highly sensitive, selective and productive. The use of SERS to perform a therapeutic drug monitoring procedure is a promising method because of its extreme sensitivity, specificity and speed of analysis.

A new approach to making silver colloid nanoparticle based SERS substrates has been demonstrated. A self-assembled silver film with plasmon resonance has been obtained by self-assembly. Four-valent ammonium salts have been used as coordinating molecules. The method is simple and does not involve complicated machinery or difficult mask making techniques that are used to fabricate SERS substrates today. It involves mixing the tetraoctylammonium bromide or tetrabutylammonium nitrate with hexane and silver nanoparticle water colloid solution in one vial, shaking it to obtain a monolayer film on hexane surface and just pouring it onto the cleaned substrate. The anodic alumina barrier layer has been used to induce more uniform self-assembly of colloid films. This SERS structure can be used in conventional plasmonics, sensors and medical applications

In this work, we have identified the size of microplastics collected from Shi Lake, China, using an optical tweezer micro-Raman spectroscopy (OTMRS) system. The microplastics were classified based on their size as products of degradation of large plastic material. Most of them were in the sub-20 μm regime. On the other hand, as nanoplastics may be more extensively distributed and hazardous than larger-sized plastics, their detection is a key point. Thus, we have designed a planar metamaterial structure and have studied the near-field enhancement in order to detect and analyze nanoplastics in aquatic environments with high sensitivity and selectivity. This study paves a way to improve our knowledge of small plastics abundance and pollution in freshwater around Shi Lake.

Here we have investigated the strong coupling of the guided modes with different orders in graphene-based onedimensional (1D) dielectric grating structures in the visible wavelengths. We found that the guided mode resonances (GMR) with different orders can strongly couple with each other under the oblique incidence of light. Absorption spectral response exhibits a distinct spectral anti-crossing with the Rabi splitting up to 59.8 meV. Simulation results further show that the strong coupling of GMR modes enables the bound state in the continuum (BIC) in this coupled system, which can be flexibly modulated by adjusting structural parameters. The proposed hybrid grating structures will benefit the applications in on-chip optical filtering, sensing, and optoelectronic detection.

In this paper, alcohol solution is added into the center hole of PCF-SPR sensor to realize the dual parameter sensor of temperature and refractive index (RI) simultaneously. Firstly, the external temperature is fixed at 20 °C, and the RI of the alcohol solution is changed. The resonance wavelength sensitivity is -6015.4 nm/RIU and the linearity is 0.99985 when the RI of alcohol solution is from 1.34 to 1.3654 with a resonance-loss sensitivity of -2640 dB/RIU and a linearity of 0.99475, respectively. When the concentration of alcohol solution is fixed at 70.4% and the external temperature of PCF is changed, the resonance loss sensitivity is 1.0375 dB/°C and the linearity is 0.976 when the external temperature is changed between 20 °C and 80 °C, its resonance loss sensitivity is 2.4219 nm/°C and the linearity is 0.9997. Finally, the sensor matrix of temperature and refractive index with respect to the shift of resonant wavelength and the change of resonant loss is obtained.

We propose an ultra-wideband polarization-conversion metasurface using a rectangular split-ring resonator (SRR) with two splits. The metasurface is numerically designed on an FR4 dielectric substrate backed by a metallic ground plane. The broadband characteristic is optimized by the genetic optimization algorithm, from which the unit cell generates a 3 dB fractional bandwidth from 5.45-15.46 GHz. This wideband polarization conversion results from multiple plasmonic resonances occurring at three neighboring frequencies (6.736, 7.367, and 13.716 GHz), and polarization conversion efficiency reaches 100% at three plasmon resonances. Owing to the sub- wavelength unit cell size and the rectangular SRRs, the response of the metasurface is independent of the polarization and incidence angle of the incoming wave, which show great practical application value and practical application prospects in optoelectronic devices, remote sensing, communication, and detection.

Si thin film is one of the promising candidates in the fields of optoelectronics and photovoltaics. However, its applications have been limited due to its poor optical absorption arising from the limited physical thickness. It has been demonstrated that such situation can be improved by taking advantage of plasmonic materials, which could enhance the optical absorption cross-section of Si through the near-field enhancement effect without increasing its physical thickness. However, embedding configuration is necessary in this case, which makes Ag and/or Au nanostructures are not suitable since they could induce some electrical defects. In this work, β-Sn-nanoparticles, which belong to IV group, have been employed to embed in the Si thin film to obtain composite thin film with better optoelectronic performance than pure Si thin film with same thickness. Both optical characterizations and finite element simulations indicate that such improvement could be attributed to the confined near-field induced by the embedded β-Sn-nanoparticles. This work could pave a way for the development of Si-based optoelectronic and/or photovoltaic devices.