Photonic Sensor Research Articles

Photonic Crystal Fiber Pollution Sensor based on Surface Plasmon Resonance

In this work, a pollution-sensitive Photonic Crystal Fiber (PCF) based on Surface Plasmon Resonance (SPR) technology is designed and implemented for sensing refractive indices and concentrations of polluted water . The overall construction of the sensor is achieved by splicing short lengths of PCF (ESM-12) solid core on one side with traditional multimode fiber (MMF) and depositing a gold nanofilm of 50nm thickness on the end of the PCF sensor. The PCF- SPR experiment was carried out with various samples of polluted water including(distilled water, draining water, dirty pond water, chemical water, salty water and oiled water). The location of the resonant wavelength peaks is seen to move to longer wavelengths (red shift) as the refractive index increases due to the transfer of maximum energy from the reflected power of the light guided through the fiber to the surface plasmons. The experimental results show that the highest sensitivity reached 4202.6nm/RIU for oiled water, the signal to noise ratio was 0.625, the resolution was 2.4*10-5 RIU, and the figure of merit was 22.8. The prepared sensor exhibited excellent performance features, making it an excellent element for detecting water pollutants.

Cost-effective silicon-photonic biosensors using doped silicon detectors and a broadband source.

We propose and demonstrate a cost-effective, microring-based, silicon photonic sensor that uses doped silicon detectors and a broadband source. Shifts in the sensing microring resonances are electrically tracked by a doped second microring, which acts as both a tracking element and a photodetector. By tracking the power supplied to this second ring, as the sensing ring's resonance shifts, the effective refractive index change caused by the analyte is determined. This design reduces the cost of the system by eliminating high-cost, high-resolution tunable lasers, and is fully compatible with high-temperature fabrication processes. We report a bulk sensitivity of 61.8 nm/RIU and a system limit of detection of 9.8x10-4 RIU.

Innovative Photonic Sensors for Safety and Security, Part I: Fundamentals, Infrastructural and Ground Transportations.

Our group, involving researchers from different universities in Campania, Italy, has been working for the last twenty years in the field of photonic sensors for safety and security in healthcare, industrial and environment applications. This is the first in a series of three companion papers. In this paper, we introduce the main concepts of the technologies employed for the realization of our photonic sensors. Then, we review our main results concerning the innovative applications for infrastructural and transportation monitoring.

Assessment of Bloch surface wave-based one-dimensional photonic crystal sensor using ultraviolet range

To generate resonance in the ultraviolet (UV) wavelength region, we have developed a Bragg mirror structure with a SiO2 top layer. This paper shows the wavelength at which sensitivity occurs by modifying the architecture of the one-dimensional photonic crystal (1D-PhC) structure appropriately. The structural parameters are adjusted to excite a Bloch surface wave with a wavelength of 256 and 281 nm at the top interface, which are the operational wavelengths. The spectrum’s distribution of electric fields and mode confinement confirmed the suggested structure with an 8-nm thick defect layer. The proposed design is empathetic at UV wavelength with varying analyte’s refractive index value. The investigation shows that the sensitivity is about 107.42 and 101.85 deg/RIU, and the quality factor is 1426.17 and 1708.14 nm at UV wavelengths of 281 and 256 nm, respectively.

Innovative Photonic Sensors for Safety and Security, Part II: Aerospace and Submarine Applications.

The employability of photonics technology in the modern era's highly demanding and sophisticated domain of aerospace and submarines has been an appealing challenge for the scientific communities. In this paper, we review our main results achieved so far on the use of optical fiber sensors for safety and security in innovative aerospace and submarine applications. In particular, recent results of in-field applications of optical fiber sensors in aircraft monitoring, from a weight and balance analysis to vehicle Structural Health Monitoring (SHM) and Landing Gear (LG) monitoring, are presented and discussed. Moreover, underwater fiber-optic hydrophones are presented from the design to marine application.

One-dimensional photonic crystal magnetic sensors based on incomplete surface defect patterns

We propose and study an innovative magnetic sensor of incomplete surface defect one-dimensional (1D) photonic crystal composed of magnetic fluid, SiO2, and TiO2 as defect layers. The magnetic fluid film covers the surface of the 1D photonic crystal, whereas the magnetic fluid penetrates into the array of circular holes with period ∧ inscribed on the dielectric layers of SiO2 and TiO2 to form the incomplete surface defect layer. The sensing characteristics of a 1D photonic crystal magnetic sensor (1D-PCMS) were analyzed using the theory of rigorous coupled wave analysis. The innovative use of the angular interrogation method in magnetic field detection has investigated the effect of defect layer structure parameters, optical dielectric loss on magnetic sensor sensitivity and quality factor at a fixed wavelength. This incomplete surface defect mode 1D-PCMS structure demonstrates the feasibility of scanning angular measurements of magnetic fields and provides a reference for future research on 1D-PCMS based on angular interrogation.

Editorial: Applications of photonic sensors in smart cities

Editorial: Applications of photonic sensors in smart cities

Design and numerical investigation of a dual-core photonic crystal fiber refractive index sensor for cancer cells detection

Design and numerical investigation of a dual-core photonic crystal fiber refractive index sensor for cancer cells detection

H-Polarised EM-Wave Transport in Polymeric-Chalcogenide Columnar Photonic Materials

The propagation of H-polarized electromagnetic (EM) waves in polymeric (PEI)-chalcogenide (As2Se3) photonic materials (PCCPM) has been theoretically optimized and investigated in the current work. We used the Transfer Matrix Technique (TMT) and Hankel Realism (HR) in columnar coordinates to show numerical findings for the unit columnar junction and columnar slab for both polymeric (low refractive index) and chalcogenide (high refractive index) materials composed at least loss wavelength window (632.8 nm). The optical transmittance with wavelength for both materials for the cylindrical unitary slab displays oscillating and non-oscillating signatures, indicating that the starting radius has a significant impact on the transmittance at a constant slab width. The oscillatory transmittance becomes squizzing when the starting radius is increased. Furthermore, for smaller modal numbers, optical transmittance is an oscillatory function of slab thickness, and for (m=4), it becomes minimum and flat. These scientific breakthroughs pave the door for a variety of photonic devices and sensor applications.

Enhancing the Performance of Photonic Sensor Using Machine-Learning Approach

This article reports on the implementation of adequate machine-learning (ML) models on different datasets vis-a-vis fiber-optic plasmonic sensor devices. The variation of the sensor’s figure of merit (FOM) with light wavelength ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> ) and metal layer thickness ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${d}_{m}$ </tex-math></inline-formula> ) is considered as a starting point and accordingly, the appropriate ML model is chosen. The FOM datasets were found to be consistent with the Gaussian process regressor (GPR) model. The application of GPR with finer resolution (0.001 nm) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> on the datasets led to enhanced magnitudes of the sensor’s FOM. The dataset (459 points) having nine different values of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${d}_{m}$ </tex-math></inline-formula> led to a predicted FOM of 6526.23 at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda =1099.343$ </tex-math></inline-formula> nm. Furthermore, the dataset (714 points) having 13 different values of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${d}_{m}$ </tex-math></inline-formula> led to a predicted FOM value of 6356.98 at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda =1099.345$ </tex-math></inline-formula> nm. These are promising results as far as the application of the sensor in biosensing is concerned. Furthermore, the chosen model is found to be highly consistent with the data in terms of trend matching, and the values of other evaluation parameters [e.g., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}^{\,{2}}$ </tex-math></inline-formula> and mean absolute error (MAE)] are found to be in considerably desirable ranges. This study clearly reveals that the selection of an appropriate ML model and its implementation on various datasets can lead to more efficient finalization of the sensor design with enhanced sensing performance. This process is critical before the actual experimental realization of the finalized sensor design.

A Robust Method for the Elaboration of SiO2-Based Colloidal Crystals as a Template for Inverse Opal Structures.

Photonic crystals (PCs) are nanomaterials with photonic properties made up of periodically modulated dielectric materials that reflect light between a wavelength range located in the photonic band gap. Colloidal PCs (C-PC) have been proposed for several applications such as optical platforms for the formation of physical, chemical, and biological sensors based on a chromatic response to an external stimulus. In this work, a robust protocol for the elaboration of photonic crystals based on SiO2 particle (SP) deposition using the vertical lifting method was studied. A wide range of lifting speeds and particle suspension concentrations were investigated by evaluating the C-PC reflectance spectrum. Thinner and higher reflectance peaks were obtained with a decrease in the lifting speed and an increase in the SP concentrations up to certain values. Seven batches of twelve C-PCs employing a SP 3% suspension and a lifting speed of 0.28 µm/s were prepared to test the reproducibility of this method. Every C-PC fabricated in this assay has a wavelength peak in a range of 10 nm and a peak width lower than 90 nm. Inverse-opal polymeric films with a highly porous and interconnected morphology were obtained using the developed C-PC as a template. Overall, these results showed that reproducible colloidal crystals could be elaborated on a large scale with a simple apparatus in a short period, providing a step forward in the scale-up of the fabrication of photonic colloidal crystal and IO structures as those employed for the elaboration of photonic polymeric sensors.

Strong optomechanical interactions with long-lived fundamental acoustic waves

Traveling-wave optomechanical interactions, known as Brillouin interactions, have now been established as a powerful and versatile resource for photonic sources, sensors, and radio-frequency processors. However, established Brillouin-based interactions with sufficient interaction strengths involve short phonon lifetimes, which critically limit their performance for applications, including radio-frequency filtering and optomechanical storage devices. Here, we investigate a new paradigm of optomechanical interactions with tightly confined fundamental acoustic modes, which enables the unique and desirable combination of high optomechanical coupling, long phonon lifetimes, tunable phonon frequencies, and single-sideband amplification. Using sensitive four-wave mixing spectroscopy controlling for noise and spatial mode coupling, optomechanical interactions with long &gt; --> 2 µ s phonon lifetimes and strong &gt; --> 400 W − 1 m − 1 coupling are observed in a tapered fiber. In addition, we demonstrate novel phonon self-interference effects resulting from the unique combination of an axially varying device geometry with long phonon lifetimes. A generalized theoretical model, in excellent agreement with experiments, is developed with broad applicability to inhomogeneous optomechanical systems.

Specific Alcohol-Responsive Photonic Crystal Sensors Based on Host-Guest Recognition

A photonic crystal material based on β-cyclodextrin (β-CD) with adsorption capacity is reported. The materials ((A-β-CD)-AM PC) consist of 3D poly (methyl methacrylate) (PMMA) colloidal microsphere arrays and hydrogels supplemented with β-cyclodextrin modified by acryloyl chloride. The prepared materials are then utilized for VOCs gas sensing. The 3D O-(A-β-CD)-AM PC was used to detect toluene, xylene, and acetone and the response was seen as the red-shift of the reflection peak. The 3D I-(A-β-CD)-AM PC was used to detect toluene, xylene, and acetone which occurred redshifted, while methanol, ethanol, and propanol and the peaks' red-shifting was observed. However, among these, methanol gave the largest red-shift response The sensor has broad prospects in the detection of alcohol and the detection of alcohol-loaded drug releases in the future.

Advances in Photonic Crystal Fiber-Based Sensor for Detection of Physical and Biochemical Parameters—A Review

The promising properties of photonic crystal fibers (PCFs) have sparked the interest of a number of research organizations. Due to the PCF’s air holes, liquid or gas samples can be inserted into them. This permits a well-controlled interaction between confined light and sensing samples, enabling the development of novel sensing applications. That was never conceivable with conventional optical fibers. PCF applications in sensing fields can be divided into physical sensors and biochemical sensors based on the parameter being measured. Physical sensors measure pressure, temperature, refractive index (RI), curvature, vibration, torsion, electric field, and displacement, among other physical characteristics. Biochemical sensors can detect chemical and biological (such as antibodies, cells, bacteria, enzymes, viruses, nucleic acids, etc.) substances. The measurement of the chemical RI is a crucial component of biochemical sensors. Due to their close relationship with biosensors, chemical sensors are commonly referred to as biochemical sensors. This article covers the detecting capabilities of surface plasmon resonance (SPR)-based PCF biochemical and physical sensors in addition to a variety of ways to enhance their sensing capacities.

Photonic crystal fiber (PhCF) for petrochemical sensing

A square-core photonic crystal fiber (PhCF) has been presented for liquid (petrochemical) sensing application. The sensor performance has been studied numerically in the frequency range from 1.2 to 3.8 THz. The core hole is filled with pure petrol, kerosene, and diesel. Strut size is varied to explore the sensor’s performance and the analysis is performed in terahertz (THz) frequencies. The photonic crystal fiber sensor shows a relative sensitivity of around 97.0% and a confinement loss in the order of 10−14 at 3.7 THz. This photonic crystal fiber sensor can be fabricated using extrusion and 3D-printing technologies.

Modeling and analysis of photonic sensor based on ring resonator for glucose detection

Modeling and analysis of photonic sensor based on ring resonator for glucose detection

Highly Sensitive Multi-Channel Biosensor for Low-Interference Simultaneous Detection

In this paper, we propose a multi-channel photonic crystal fiber sensor, which adopts dual-polarization and multiple materials to effectively reduce the mutual interference between channels and enhance the surface plasmon resonance, thus achieving simultaneous detection of a multi-channel with low interference. Four channels are polished around the cylindrical fiber, and then different metal films (gold or silver) and plasmonic materials (titanium dioxide, thallium pentoxide, or graphene) are added to the sensing area of each channel. All channels detect refractive indices in the range of 1.34 to 1.42. The sensing performance of the fiber optic sensor was numerically investigated using the full vector finite element method. After the optimization of structural parameters, the maximum wavelength sensitivity of channel-1, channel-2, channel-3, and channel-4 are 49,800 nm/RIU, 49,000 nm/RIU, 35,900 nm/RIU, and 36,800 nm/RIU, respectively. We have theoretically analyzed the sensor's capabilities for partial bio-detection and simulated its detection capability with a wavelength sensitivity of 11,500 nm/RIU for normal red blood cells and 12,200 nm/RIU for MCF-7 cancerous cells. Our proposed sensor has a novel design, can detect multiple channels simultaneously, has strong anti-interference capability and high sensitivity, and has good sensing characteristics.

High-Sensitivity Early Detection Biomedical Sensor for Tuberculosis With Low Losses in the Terahertz Regime Based on Photonic Crystal Fiber Technology

Tuberculosis is one of the most contagious and lethal illnesses in the world, according to the World Health Organization. Tuberculosis had the leading mortality rate as a result of a single infection, ranking above HIV/AIDS. Early detection is an essential factor in patient treatment and can improve the survival rate. Detection methods should have high mobility, high accuracy, fast detection, and low losses. This work presents a novel biomedical photonic crystal fiber sensor, which can accurately detect and distinguish between the different types of tuberculosis bacteria. The designed sensor detects these types with high relative sensitivity and negligible losses compared to other photonic crystal fiber-based biomedical sensors. The proposed sensor exhibits a relative sensitivity of 90.6%, an effective area of 4.342×10−8m2, with a negligible confinement loss of 3.13×10−9cm−1, a remarkably low effective material loss of 0.0132cm−1, and a numerical aperture of 0.3462. The proposed sensor is capable of operating in the terahertz regimes over a wide range (1 THz–2.4THz). An abbreviated review of non-optical detection techniques is also presented. An in-depth comparison between this work and recent related photonic crystal fiber-based literature is drawn to validate the efficacy and authenticity of the proposed design.

1-Dimensional silicon photonic crystal pressure sensor for the measurement of low pressure

In this article we proposed a one-dimensional (1D) silicon photonic-crystal (PC) as a highly sensitive pressure sensor to measure the applied hydrostatic pressure. A 1D flexible silicon layer is formed at the top of the proposed structure. The proposed sensor is designed to measure the low pressure in the range of 10kpa to 20kpa. An FEM tool Comsol Multiphysics is used to design, simulate and analyze the structure. A central cavity is created to support the resonant mode and shift in the resonant mode is observed with the varying boundary load. With the variation in the applied pressure from 10kpa to 20kpa, shift in the resonant mode towards higher wavelength region was observed. The defect cavity length and number of layers were tuned to get optimized results. The novelty of this work includes, use of silicon material to sense the applied pressure, design and its simulation to obtain electric field distribution in the multi-layer structure and its analysis for sensing the applied boundary load using an FEM tool. Simulation results shows that the proposed sensor has a very high sensitivity of 350 nm/GPa and Q-factor of 40,104 with the transmission of 99.99 %.

Nanogap enhancement of the refractometric sensitivity at quasi-bound states in the continuum in all-dielectric metasurfaces

Abstract All-dielectric metasurfaces have great potential as highly sensitive refractometric sensors relying on their spectral shifts because of an extensive range of design flexibilities and their smaller absorption losses than plasmonic platforms. However, simultaneously realizing both high quality (Q) factors and the large interplay of light with external medium in such photonic sensors remains one of the key challenges for their better performance. This study proposes silicon block metasurfaces with nanogaps to overcome this challenge based on quasi-bound states in the continuum (BICs). We show that the metasurface has two quasi-BIC modes—magnetic dipole (MD) and electric quadrupole (EQ)—and their electric fields experience large enhancement at the ∼30 nm nanogap regions. Consequently, introducing nanogaps into the metasurfaces increases the environmental refractive index sensitivity by up to 2.7 times in the MD mode while keeping the high Q factors and achieves the figure-of-merit (FOM) of 239. In addition, we show that the appropriate selection of the amount of asymmetry is needed under the trade-off between the FOM and spectral signal-to-noise ratio, which provides design guidelines for highly sensitive biosensors based on quasi-BICs.