Ultrasensitive Deep-Ultraviolet Surface Plasmon Resonance Sensors Using Aluminum-Graphene Metasurface: a Theoretical Insight

Plasmonics - This study investigates a versatile deep-ultraviolet (DUV) surface plasmon resonance (SPR) sensor by integrating a few graphene layers into low-cost aluminum (Al) thin film. The...     

A Novel Diamond Ring Fiber-Based Surface Plasmon Resonance Sensor

We propose a highly sensitive novel diamond ring fiber (DRF)-based surface plasmon resonance (SPR) sensor for refractive index sensing. Chemically active plasmonic material (gold) layer is coated inside the large cavity of DRF, and the analyte is infiltrated directly through the fiber instead of selective infiltration. The light guiding properties and sensing performances are numerically investigated using the finite element method (FEM). The proposed sensor shows a maximum wavelength and amplitude interrogation sensitivity of 6000 nm/RIU and 508 RIU^?1, respectively, over the refractive index range of 1.33–1.39. Additionally, it also shows a sensor resolution of 1.67 × 10^?5 and 1.97 × 10^?5 RIU by following the wavelength and amplitude interrogation methods, respectively. The proposed diamond ring fiber has been fabricated following the standard stack-and-draw method to show the feasibility of the proposed sensor. Due to fabrication feasibility and promising results, the proposed DRF SPR sensor can be an effective tool in biochemical and biological analyte detection.     

偏振干涉角度调制SPR传感技术研究及应用进展

针对一种新兴生物检测方法——表面等离子体波共振(SPR)技术,文中SPR传感系统采用偏振干涉和角度调制方案,使SPR传感灵敏度与光复反射系数的模和相位都相关,从而实现较大线形范围内的高灵敏测量。同时开展了该SPR传感系统在环保领域的应用研究,SPR共振信号可实时随甲烷含量线性改变,气体检测灵敏度达到1 070ppm,实验结果验证了这种SPR传感技术的检测性能并显示了其在环保监测领域的应用潜力。     

Electrically Tunable Fiber Optic Sensor Based on Surface Plasmon Resonance

The response of optical fiber surface plasmon resonance (SPR) sensor to potential is monitored in real time. The potential-induced reflectance of a gold-coated optical fiber SPR probe is dependent on potential step width and ionic strength. Wider potential step and stronger ionic strength are generally able to enhance the reflectance and accelerate the response time. The specifically adsorptive anion Cl^? provides a pronounced effect on a potential-dependent SPR probe. The exclusive contact of the SPR probe with anion Cl^? could significantly slow down the optical response. The work offers opportunities for optical fiber SPR probes to characterize the electrochemical application.     

Waveguide-Coupled Surface Plasmon Resonance Sensor for Both Liquid and Gas Detections

Plasmonics - In this paper, we propose a novel surface plasmon resonance sensor for both liquid and gas detections, which is based on the two dielectric planar waveguide (PWG)-coupled plasmonic...     

High-Performance Magneto-Optic Surface Plasmon Resonance Sensor Design: An Optimization Approach

High-performance intensity-interrogated magneto-optic surface plasmon resonance (MOSPR) sensors are designed by a multi-objective optimization approach. Designed devices show bulk refractive index sensitivity 1 order of magnitude larger than the current state of the art, while the design procedure allows to chose an appropriate trade-off between sensor performance and ease of fabrication. Straightforward guidelines for the sensor design and fabrication emerge from the optimization process, indicating that minimization of the optical losses takes precedence on the maximization of the magneto-optical modulation.     

Refractive Index Sensor Using Long-Range Surface Plasmon Resonance with Prism Coupler

Plasmonics - Long-range surface plasmon resonance (LRSPR)-based sensors exhibit high sensitivity as compared to the conventional SPR sensors due to low losses. A high refractive index prism and low...     

Influence of Dielectric Coating on Performance of Surface Plasmon Resonance Sensor

Plasmonics - In the present study, the nature of dielectric layer above metal layer in surface plasmon resonance sensor is investigated. The performance-defining parameters, i.e., shift in...     

Surface Plasmon Resonance Based Fiber Optic Ammonia Sensor Utilizing Bromocresol Purple

In this paper, a surface plasmon resonance (SPR) based fiber optic ammonia gas sensor has been designed and fabricated using bromocresol purple (BCP) as sensing element. The sensor works under wavelength modulation scheme. The detection of ammonia gas has been carried out at room temperature. Three different kinds of film coating configurations, namely silver + BCP, gold + BCP, and silver + silicon + BCP on the unclad portion of the fiber have been used for studying the role of each layer. Further, to optimize the performance of the sensor, the films of varying thicknesses were coated using thermal evaporation technique. Experiments have been performed for the ammonia concentrations ranging from 0 to 150 ppm around the probe. To record the SPR spectrum, light from a polychromatic source is launched in the fiber and the spectrum is recorded at the other end of the fiber. The spectrum has a peak at lower wavelength while a dip at the higher wavelength. The dip corresponds to SPR while the peak appears to be due to fluorescence properties of the dye. It has been observed that as the ammonia gas comes in contact of the BCP layer, it changes the refractive index of the BCP dye which, in turn, changes the resonance wavelength. Further, the change in refractive index increases as the concentration of ammonia gas increases up to certain concentration of ammonia after that it saturates. Silicon layer has been shown as a protection layer for silver and gold from oxidation and acts as a tuner of wavelength. The proposed ammonia sensor has small response as well as recovery time.     

Graphene-MoS2 Hybrid Structure Enhanced Fiber Optic Surface Plasmon Resonance Sensor

Plasmonics - In this paper, a fiber optic surface plasmon resonance sensor based on graphene-MoS2 hybrid structure is presented. The wavelength interrogation method is employed to analyze the...     

Light Humidity Sensor of Surface Plasmon Resonance by Symmetric Metal Film

The field of plasmonics has experienced a renaissance in recent years by providing a large variety of new physical effects and applications. Here, we demonstrate a light humidity sensor of surface plasmon resonance (SPR) by a symmetric metal film, which uses P polarised light of emergent He–Ne laser to stimulate SPR. Resonance angle change received by the spectrum detector can determine humidity via the relationship between humidity and effective refractive index. When the relatively short wavelengths are shown in the model, the evanescent wave penetration depth is shallow, resonance state is weak and energy loss is low. The opposite results are obtained, when the wavelength is long. Also, with increasing thickness, the resonance peak becomes acute, thereby indicating the improvement in detection accuracy. When the metal thickness of our model is 50 nm, the resonance peak of the reflection spectrum is narrower, accuracy is high and reflectivity is close to 0. By analysing the experimental results, the SPR resonance phenomenon is shown. The electromagnetic field energy is highly concentrated near the interface between the metal and SiO₂, which appears highly localized. The resolution of the structure can reach 0.37% RH (relative humidity), which is significantly more than the resolution of capacitive humidity sensor, i.e., resolution is usually 1% RH to 2% RH. The optical sensor of our development can provide a key device for long-distance transmission sensing, in special conditions such as low temperature.

     

Nano-gap-Enhanced Surface Plasmon Resonance Sensors

This paper analyzes how dual-mode surface plasmon resonance sensors can be further improved if one were to introduce small (∼20 nm) gaps in the film surface. First, a figure of merit, the sensor’s limit of detection (LOD), is defined in order to optimize the design of the nano-gap sensor. Secondly, the LOD of this design is compared with that of an optimized planar dual-mode design. Through this analysis, it is shown that the LOD of the planar sensor can be improved upon by around a factor of 7 when compared with the nano-gap-enhanced design. Furthermore, with the nano-gap design, the lower wavelength plasmon mode demonstrates remarkably improved selectivity when compared with the conventional sensor. In order to explain these results, the dispersion of each plasmon mode along with the electromagnetic field profiles are modeled and analyzed.     

Graphene/Au-Enhanced Plastic Clad Silica Fiber Optic Surface Plasmon Resonance Sensor

Owing to its large surface-to-volume ratio and good biocompatibility, graphene has been identified as a highly promising candidate as the sensing layer for fiber optic sensors. In this paper, a graphene/Au-enhanced plastic clad silica (PCS) fiber optic surface plasmon resonance (SPR) sensor is presented. A sheet of graphene is employed as a sensing layer coated around the Au film on the PCS fiber surface. The PCS fiber is chosen to overcome the shortcomings of the structured microfibers and construct a more stable and reliable device. It is demonstrated that the introduction of graphene can enhance the intensity of the confined electric field surrounding the sensing layer, which results in a stronger light-matter interaction and thereby the improved sensitivity. The sensitivity of graphene-based fiber optic SPR sensor exhibits more than two times larger than that of the conventional gold film SPR fiber optic sensor. Furthermore, the dynamic response analyses reveal that the graphene/Au fiber optic SPR sensor exhibits a fast response (5 s response time) and excellent reusability (3.5% fluctuation) to the protein biomolecules. Such a graphene/Au fiber optic SPR sensor with high sensitivity and fast response shows a great promise for the future biochemical application.     

Extra-broad Photonic Crystal Fiber Refractive Index Sensor Based on Surface Plasmon Resonance

Plasmonics - We propose and investigate a photonic crystal fiber (PCF) refractive index sensor with triangular lattice and four large-size channels based on surface plasmon resonance. In such...     

A Waveguide-Coupled Surface Plasmon Resonance Sensor Using an Au-MgF2-Au Structure

Plasmonics - We describe an Au-MgF2-Au trilayered waveguide-coupled surface plasmon resonance (WCSPR) sensor in this article. The characteristics of this sensing structure are compared with those...     

Fiber-based Surface Plasmon Resonance Sensor for Lead Ion Detection in Aqueous Solution

Plasmonics - Maghemite/reduced graphene oxide nanocomposite has been successfully deposited onto the surface of a gold-coated D-shaped optical fiber. The synergetic combination of gold, graphene,...     

Liquid Crystal-Based Surface Plasmon Resonance Biosensor

Plasmonics - Surface plasmon resonance has many applications in designing biosensors. In this paper, an easy fabrication liquid crystal-based surface plasmon resonance (LC-SPR) biosensor is...     

Highly Sensitive Surface Plasmon Resonance Based D-Shaped Photonic Crystal Fiber Refractive Index Sensor

In this article, a D-shaped photonic crystal fiber based surface plasmon resonance sensor is proposed for refractive index sensing. Surface plasmon resonance effect between surface plasmon polariton modes and fiber core modes of the designed D-shaped photonic crystal fiber is used to measure the refractive index of the analyte. By using finite element method, the sensing properties of the proposed sensor are investigated, and a very high average sensitivity of 7700 nm/RIU with the resolution of 1.30 × 10^?5 RIU is obtained for the analyte of different refractive indices varies from 1.43 to 1.46. In the proposed sensor, the analyte and coating of gold are placed on the plane surface of the photonic crystal fiber, hence there is no necessity of the filling of voids, thus it is gentle to apply and easy to use.     

Analysis of Graphene-Based Photonic Crystal Fiber Sensor Using Birefringence and Surface Plasmon Resonance

Plasmonics - We present and numerically characterize a photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor. By adjusting the air hole sizes of the PCF, the effective...     

Imaging of Surfaces by Concurrent Surface Plasmon Resonance and Surface Plasmon Resonance-Enhanced Fluorescence

Surface plasmon resonance imaging and surface plasmon induced fluorescent are sensitive tools for surface analysis. However, existing instruments in this area have provided limited capability for concurrent detection, and may be large and expensive. We demonstrate a highly cost-effective system capable of concurrent surface plasmon resonance microscopy (SPRM) and surface plasmon resonance-enhanced fluorescence (SPRF) imaging, allowing for simultaneous monitoring of reflectivity and fluorescence from discrete spatial regions. The instrument allows for high performance imaging and quantitative measurements with surface plasmon resonance, and surface plasmon induced fluorescence, with inexpensive off-the-shelf components.