This research article proposes a current-mode circuit-based memristor emulator. The proposed emulator distinguishes itself from others in the literature through its simplicity and high-frequency responsiveness (100 MHz). It supports both increasing and decreasing modes of operation. A Comprehensive analysis of non-ideal behavior, including parasitic effects, temperature, and process corner variations, ensures the robustness of the proposed emulator. The suggested emulator is used to design a relaxation oscillator for biomedical applications and adaptive neural network for neuromorphic application. The proposed memristor emulator’s design and verification are performed using a 180 nm CMOS technology. The proposed design has also been verified using ICs CA3080 and AD844.

Surface plasmon resonance (SPR) has become a versatile label-free optical sensing approach for measuring chemical and biomolecular interactions, providing rapid, real-time, and ultra-sensitive responses. The single-metal-layer SPR sensors have high damping loss, broad resonance characteristics, and low molecular adsorption efficiency. The most recent progress includes advanced functional materials, multilayer structures, and catalytic nanocomposite interfaces to enhance plasmonic field confinement and sensing sensitivity with more degrees of freedom. In this review, we will provide an inclusive and application-dependent survey of the 2D-material-based sensing platform, especially for environmental monitoring, food quality detection, and bio-diagnostics. They systematically discuss the rest and sensing properties, including sensitivity, figure of merit (FOM), quality factor (QF), and limit of detection (LOD) based on the operating principles as well as optical structures used for sensing, to clarify the structure-sensing characteristic relationship. Special attention is given to phosphorus-derived compounds, transition metal dichalcogenides (TMDCs), high-refractive-index (RI) dielectric layers, and polymer- and biopolymer-modified sensing layers to improve analyte capture and interfacial charge transfer. In this review, plasmonic platforms (PP) integrated with nanocomposites and nanozymes for catalytic signal amplification and ultra-trace detection are reviewed from a critical perspective. Furthermore, comparative performance evaluation, fabrication reproducibility, and stability limitations are analyzed along with emerging directions such as artificial intelligence (AI)- assisted sensor design, wearable plasmonic devices, quantum Plasmonics, and self-powered sensing. The review outlines performance-driven design strategies for next-generation high-sensitivity and portable SPR sensing systems.

We demonstrate an engineered structure ZnO/TiO 2 based photonic biosensor for label-free detection of lung cancer cells (A549). Proposed device exhibits 35 μA variation in photocurrent when A549 cells are present compared to PBS media.

We demonstrate multi-channel photonic circuit using Ag/SiO 2 /ITO on silicon, enabling electrically reconfigurable channel removal with 27 dB on/off ratio at ±2 V . The compact, low-voltage device offers strong potential for scalable optical memory and computing.

Two-dimensional semiconductors have attracted considerable interest for integration into emerging quantum photonic networks. Strain engineering of monolayer transition-metal dichalcogenides (ML-TMDs) enables the tuning of light-matter interactions and associated optoelectronic properties, and generates new functionalities, including the formation of quantum dots (QDs). Here, we combine spatially resolved micro-photoluminescence (μ-PL) spectroscopy from cryogenic (4-94 K) to room temperature with micro-Raman spectroscopy at room temperature to investigate the strain-dependent emission energies of thousands of individual QDs in ML-WS_2 and ML-WSe_2, integrated across multiple heterostructures and a piezoelectric device. Compared with delocalized excitons, QDs in both materials exhibit enhanced strain sensitivities of their emission energies - approximately fourfold in WS_2 and twofold in WSe_2 - leading to pronounced broadening of the ensemble emission linewidth. Temperature-dependent μ-PL spectroscopy combined with dynamic strain tuning experiments further reveal that the enhanced strain sensitivity of individual QDs originates from strengthened interactions with low-energy phonons induced by quantum confinement. Our results demonstrate a versatile strain-engineering approach with potential for spectral matching across solid-state, atomic, and hybrid quantum photonic networks, and provide new insights into phonon-QD interactions in two-dimensional semiconductors.

This study presents a comprehensive simulation-based investigation of a 1 & times; 16 channel optical phased array (OPA), highlighting the advantages of utilizing Si-ITO phase shifters over conventional Si-based devices. Through rigorous FDTD simulations, we achieved a compact OPA design with dimensions of 0.07mm & times; 0.02mm, demonstrating remarkable steering capabilities. The Si-ITO phase shifters enabled a wide lateral steering range of 56 degrees, surpassing the performance of conventional phase shifters that would require significantly larger apertures to achieve similar results. Additionally, we achieved a 23 degrees longitudinal steering range through wavelength tuning from 1.5 mu m to 1.6 mu m, with a divergence angle of 3.5(degrees) & times; 7.5(degrees). The use of Si-ITO as a phase shifter, owing to its superior electro-optic effect, addresses the inherent limitations of traditional phase shifters, particularly their larger footprints. The chip-scale dimensions of ITO play a crucial role in achieving compact phase shifters, essential for high-density on-chip packaging. This advancement in Si-ITO technology holds significant promise for the development of compact, efficient, and high-performance OPAs for future on-chip optical communication systems.

Minimizing the footprint of nonvolatile photonic memories is essential for high-density programmable photonic integrated circuits. Here, we present an ultra-compact grating-coupled nanophotonic resistive switch based on a hybrid Ag/SiO2/ITO platform on an SOI substrate. The engineered device simultaneously integrates optical coupling, hybrid mode confinement, and resistive switching within a single engineered grating structure, resulting in a total device length of only ~24 µm, including the input coupling, active switching, and output coupling regions. Strong optical confinement within the ultrathin SiO2 layer enables efficient electro-optic modulation with an extinction ratio of 19.4 dB. The device exhibits stable bipolar switching with SET/RESET voltages of +3.2 V/-3 V, endurance over 200 cycles, and retention exceeding 104 s. Transient measurements reveal successful switching under 5 µs programming pulses with an effective switching time of ~100 ns. The demonstrated ultra-compact footprint and nonvolatile optical functionality make the proposed device promising for high-density photonic memories, programmable photonic integrated circuits, nonvolatile photonic computing, and memory systems.

Single-photon emitters (SPEs) hosted by two-dimensional (2D) semiconducting materials are envisioned for next-generation quantum applications. However, SPE creation in 2D semiconductors on rigid substrates like SiO2/Si via nanoindentation is a technological gap, critical for interfacing SPEs with photonic circuits and cavities. Here, we report a protocol for deterministically creating SPEs in monolayer WSe2 on SiO2/Si substrates using a sharp diamond AFM (atomic force microscope) tip. A displacement-controlled indentation process is developed, allowing indent depths > 150 nm necessary for creating SPEs. Sharp defect peaks ( 200 μeV) are observed in cryogenic (4K) photoluminescence (PL) spectrum at nanoindented sites and are stable upto 120K. 76

Reconfigurable, high-speed, and energy-efficient modulators are central to the advancement of next-generation optical communication and signal processing systems. Here, we demonstrate a micro-ring modulator based on semiconductor heterojunctions of silicon and indium tin oxide (ITO). The device exploits field-effect induced refractive index tuning in accumulation layer of ITO which has strong plasma dispersion and epsilon near zero (ENZ) effect enabling efficient electro-optic modulation with ultra-compact device footprint. A voltage-tunable spectral range with a wavelength shift of 1 nm, corresponding to EO tuning efficiency of 0.5 nm/V is reported. The 20 & micro;m long device achieves a high extinction ratio of 21 dB and electrical bandwidth of 26.5 GHz which enables the high-speed operation of more than 50 Gbps while maintaining low energy consumption of 0.112 pJ/bit, positioning the device among the most efficient integrated modulators based on ITO. The reported results establish the Si-ITO ring modulator as a compact, CMOS-compatible platform for wavelength-selective modulation and tunable filters with potential for applications in microwave photonic signal processing, and neuromorphic photonic computing applications.

This paper proposes a CMOS- compatible plasmonic sensor based on titanium nitride (TiN), a transition metal nitride, as an alternative to conventional noble metal-based sensors like silver and gold. Excellent optical tunability, enhanced mechanical and thermal stability, and compatibility with traditional CMOS production techniques are just a few of the exceptional qualities that make TiN the material of choice. The sensor design features a square ring resonator structure arranged in a TiN-insulator-TiN configuration. The sensor design consists of a square ring resonator structure which is arranged in a TiN-insulator-TiN configuration. The working principle of the sensor is that when the material inside the resonator changes, the resonance wavelength shifts, allowing the corresponding refractive index to be measured to identify the unknown material. Numerical simulations are performed using the finite-difference time-domain (FDTD) method, with the Lorentz-Drude model employed to define the complex permittivity of TiN. Optimizing geometrical parameters, such as increasing the length of the square ring's sides from 300 nm to 360 nm, enhances sensor sensitivity, accompanied by a redshift in the resonance wavelength toward the near-infrared region. The optimized design achieves a maximum sensitivity of 1613 nm/RIU, showing its potential for a high-precision refractive index (RI) sensor. Moreover, due to the excellent thermal properties of TiN, the sensor can be a promising choice for temperature sensing applications operated under elevated temperatures. The sensor is evaluated for temperature sensing using polydimethylsiloxane (PDMS) as a thermo-responsive medium, covering temperatures from 0 degrees C to 100 degrees C, with a temperature sensitivity of 0.6814 nm/degrees C, demonstrating its potential to outperform conventional plasmonic sensors.

In this work, a sensitive and portable fiber-optic WaveFlex biosensor is developed for the detection of paraoxon pesticide in agricultural products. A combination of simulation and experiment is used to analyze the distribution of the evanescent field in optical fiber. The flexible W-shaped optical fiber biosensor (OFB) based on localized surface plasmon resonance (LSPR) effect is developed, also known as WaveFlex biosensor. Gold nanoparticles (AuNPs) were immobilized on the surface of the optical fiber probe to successfully excite the LSPR phenomenon. In addition, in order to modify the optical fiber probe, cerium dioxide nanorods (CeO2-NRs) and tungsten disulfide quantum dots (WS2-QDs) were functionalized. It is used to enhance the biocompatibility of the sensor and increase the specific surface area of the fiber probe. The enzymatic determination of organophosphorus pesticides (OPs) is usually based on cholinesterase and organophosphorus hydrolase. Paraoxon has an irreversible inhibitory effect on butyrylcholinesterase. The content of paraoxon was detected by the inhibitory effect of paraoxon on butyrylcholinesterase. The reproducibility, reusability, stability, selectivity, and pH tests of the W-shaped WaveFlex sensor and its application in real samples are evaluated using different concentrations of paraoxon solution. The linear range of the sensor is 0-100 mu g/mL, and the limit of detection (LoD) is 7.999 mu g/mL. The sensitivity is as high as 0.0312 nm/(mu g/mL), which verifies that the sensor provides an indispensable technology, cost-effective and portable solution for paraoxon-specific detection.

Transition metal dichalcogenides and related layered materials in their monolayer and a few layers thicknesses regime provide a promising optoelectronic platform for exploring the excitonic- and many-body physics. Here, we have investigated the effects of nanoparticle-induced local strain on the optical properties of exciton, X0, and trion, X-, in monolayer WS2. Biaxial tensile strain up to 2.0% was quantified and verified by monitoring the changes in three prominent Raman modes of WS2: E2g1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{{{\rm{E}}}}}_{2g}<^>{1}$$\end{document}(Gamma), A1g, and 2LA(M). We obtained an increase of 34 meV in X- binding energy with an average tuning rate of 17.5 +/- 2.5 meV/% strain across all the samples irrespective of the surrounding dielectric environment of monolayer WS2 and the sample preparation conditions. Strain-induced linewidth broadening and deformation potentials of both X0 and X- emission elucidate that X- binding energy increases due to strain-enhanced electron-phonon coupling. This work holds relevance for future X--based nano-opto-electro-mechanical systems and devices.

Ascorbic acid, commonly called vitamin C, is a major biomarker of many malfunctions and deficiencies in the human body. This research focuses on enhancing ascorbic acid detection sensitivity using a specialized (single-mode, multimode, and single-mode) SMS fiber structure through enzyme functionalization and leveraging localized surface plasmon resonance (LSPR). The SMS fiber structure, designed for versatility, was modified to increase selectivity by ascorbate oxidase functionalization, which oxidizes the AA in the presence of oxygen, while LSPR techniques were employed to harness plasmonic effects for improved detection capabilities using gold nanoparticles (AuNPs), whose absorbance peak wavelength appeared at 522.8 nm. The resulting sensor probe was examined for various concentrations of AA ranging from 50 to 120 µM in terms of different performance parameters such as sensitivity, limit of detection, selectivity, reproducibility, and repeatability for ascorbic acid detection and such studies could be employed in complex biological matrices for AA detection. The sensor demonstrated a sensitivity of 0.0138 nm/μM and a calibration correlation factor of 0.9181, good linearity over the range of 50–120 µM AA concentrations. Additionally, the resulting fiber structure displayed selective detection of AA, thus ensuring non-interference of other analytes present in the realistic biological matrix. This research holds promise for advanced applications in clinical diagnostics and biomedical research, offering a novel and effective approach to enhance ascorbic acid detection.

Early detection of lung cancer is crucial because of the lower survival rate for improving treatment outcomes. Chip-scale photonic biosensors offer a promising label-free and non-invasive diagnostic approach by analyzing intercellular properties. Here, we demonstrate a chip-scale photonic platform based on semiconductor heterojunctions of n-type ZnO/TiO2 with a comb-like structure to enable label-free detection of lung cancer cells. The lung cancer cells are detected using the engineered structure of the proposed photodetector through distinct fluctuations in the cells' electrical signature. The proposed voltage-controlled device configuration enhances interband transitions within the ZnO/TiO2 depletion region with strong light-matter interaction, particularly in the UV spectrum. The proposed biosensor results in an enhanced photocurrent response in the presence of A549 cells, demonstrating its high sensitivity towards lung cancer detection. The photocurrent in PBS increases from 45 μA to 80 μA when a small concentration of A549 cells (500 cells/μl) is added at a low bias of 1.6 V, demonstrating label-free detection capability. The proposed device with its engineered structure combines ZnO's efficient charge carrier transport with TiO2's proven biocompatibility, enabling sensitive and non-invasive analysis with an additional flexibility of voltage-controlled operation. The demonstrated on-chip biosensor can be a potential candidate for cancer detection, which can enable future integration with compact biosystems.

High intake of full-fat milk can lead to serious health consequences, particularly concerning cardiovascular health. The high fat content can cause an imbalance in weight and can cause lifestyle-related disorders such as obesity and heart disease. Therefore, an accurate determination of the level of milk fat is necessary to ensure the health of the general population and nutritional safety. Against this background, the current work proposes a very effective surface plasmon resonance sensing (SPR) strategy that can be utilized to measure fat levels in milk. This sensor would be made according to the Kretschmann configuration owing to its sensitivity in the detection of surface plasmon using evanescent waves at the metal dielectric interface. To improve the sensing structure, thallium arsenic selenide and superlative two-dimensional (2D) materials are used. A transfer matrix method (TMM) combined with the angular interrogation (AI) technique was used at the operating wavelength of 633 nm to determine the sensor performance. The engineered structure yields better results as it reached a maximum sensitivity of 378.36°/RIU, QF of 79.14/RIU, and DA of 1.848. These results indicate a huge improvement over those of earlier described SPR sensor designs, thereby validating the working efficiency of the suggested model in real-life detection of milk fats.

In response to the increasing demand for the prevention and control of chronic noncommunicable diseases, people are paying growing attention to the application of flexible optical waveguides in health assistance, and the specific functions of flexible optical waveguides are gradually enriched in the process. This review systematically explains the research progress of flexible optical waveguides in human health assistance. An analysis of the sensing principles used in flexible optical waveguides for signal sensing is provided. The specific applications of flexible optical waveguides in human health assistance are categorized into three main areas: invasive biomedical diagnosis and therapy, contact physiological information monitoring, and interactive soft robots. From the perspective of materials science, a comprehensive analysis is conducted on commonly used materials and their properties for flexible optical waveguides in human health assistance. Furthermore, the sensing principles and specific applications of flexible optical waveguides are provided, aiming to provide theoretical support and technological innovation direction for the construction of a new generation of intelligent health monitoring systems. The unique advantages of flexible optical waveguides in sensing, especially in human physiological signal sensing, are demonstrated through detailed theoretical analyses. Their specific applications in human health assistance are summarized under each category. Finally, this review proposes evolution paths for flexible optical waveguides by addressing current bottlenecks through material innovation (e.g., hybrids, metasurfaces), functional enhancement (e.g., self-powered sensing), and system integration (e.g., miniaturization, Internet of Things platforms).