We numerically demonstrate a surface plasmon resonance biosensor-based on dual-polarized spiral photonic crystal fiber (PCF). Chemically stable gold material is used as the active plasmonic material, which is placed on the outer layer of the PCF to facilitate practical fabrication. Finite-element method-based numerical investigations show that the proposed biosensor shows maximum wavelength sensitivity of 4600 and 4300 nm/RIU in ${x}$ - and ${y}$ -polarized modes at an analyte refractive index of 1.37. Moreover, for analyte refractive index ranging from 1.33 to 1.38, maximum amplitude sensitivities of 371.5 RIU−1 and 420.4 RIU−1 are obtained in ${x}$ - and ${y}$ -polarized modes, respectively. In addition, the effects of changing pitch, different air hole diameter of the PCF and thickness of the gold layer on the sensing performance are also investigated. Owing to high sensitivity, improved sensing resolution and appropriate linearity characteristics, the proposed dual-polarized spiral PCF can be implemented for the detection of biological analytes, organic chemicals, biomolecules, and other unknown analytes.

Spiral Photonic Crystal Fiber-Based Dual-Polarized Surface Plasmon Resonance Biosensor

Hollow-core silver coated photonic crystal fiber plasmonic sensor

We propose and numerically characterize the optical characteristics of a novel photonic crystal fiber (PCF) based surface plasmon resonance (SPR) sensor in the visible to near infrared (500-2000 nm) region for refractive index (RI) sensing. The finite element method (FEM) is used to design and study the influence of different geometric parameters on the sensing performance of the sensor. The chemically stable plasmonic material gold (Au) is used to produce excitation between the core and plasmonic mode. On a pure silica (SiO2) substrate, a rectangular structured core is used to facilitate the coupling strength between the core and the surface plasmon polariton (SPP) mode and thus improves the sensing performance. By tuning the geometric parameters, simulation results show a maximum wavelength sensitivity of 58000 nm/RIU (Refractive Index Unit) for the x polarization and 62000 nm/RIU for the y polarization for analyte refractive indices ranging from 1.33 to 1.43. Moreover, we characterize the amplitude sensitivity of the sensor that shows a maximum sensitivity of 1415 RIU-1 and 1293 RIU-1 for the x and y polarizations, respectively. To our knowledge, this is the highest sensitivity for an SPR in published literature, and facilitates future development of sensors for accurate and precise analyte measurement. The sensor also attains a maximum figure of merit (FOM) of 1140 and fine RI resolution of 1.6 × 10-6. Owing to strong coupling strength, high sensitivity, high FOM and improved sensing resolution, the proposed sensor is suited for real-time, inexpensive and accurate detection of biomedical and biological analytes, biomolecules, and organic chemicals.

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Dual-polarized highly sensitive plasmonic sensor in the visible to near-IR spectrum.

In this work, we proposed a high-resolution D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor based on gold grating. Gold grating is introduced to modulate the resonance wavelength and enhance the refractive index (RI) sensitivity. Structure parameters of PCF and gold grating are analyzed by the finite element method for optimizing the SPR sensor. The simulation results indicate that air hole pitch, air hole diameter, and gold thickness and grating constant have little influence on the sensitivity of the refractive index, which reduces the requirement of precise processing. For improving the resolution of RI sensing, a two-feature (2F) interrogation method, which combines wavelength interrogation and amplitude interrogation, is used. The maximum theoretical resolution of the SPR sensor reaches to 5.98×10-6  RIU in the range of 1.36-1.38, and the wavelength sensitivity reaches to 3340 nm/RIU. The proposed SPR sensor shows potential applications for developing a high-sensitivity, real-time, and fast-response SPR-RI sensor.

D-shaped photonic crystal fiber plasmonic refractive index sensor based on gold grating

This paper reports a novel approach for the efficient detection of blood and skin cancerous cells using PCF-based sensor. The proposed sensor contains an asymmetrical arrangement of rectangular holes where the core region is composed of a single rectangle. Zeonex is used as the fiber substance. The model is structured and numerically analyzed using the finite element method (FEM)-based software. The simulation of the proposed model validates its efficiency in cancer cell detection. Several performance parameters suggest that the proposed sensor attains optimum results at 2.0 THz. At this point, the sensitivities achieved in detecting blood cancer cells, normal cell (Jurkat), skin cancer cell, normal cell (basal), and water are 96.74, 96.56, 96.61, 96.34, and 95.69%, respectively. Besides, simulation results also suggest that the material and confinement loss are very low for this proposed sensor. Additionally, the simple rectangle-based model provides the ease of fabrication introducing prevailing strategies.

Mono-Rectangular Core Photonic Crystal Fiber (MRC-PCF) for Skin and Blood Cancer Detection

In this paper, we numerically demonstrate a two-layer circular lattice photonic crystal fiber (PCF) biosensor based on the principle of surface plasmon resonance (SPR). The finite element method (FEM) with circular perfectly matched layer (PML) boundary condition is applied to evaluate the performance of the proposed sensor. A thin gold layer is deposited outside the PCF structure, which acts as the plasmonic material for this design. The sensing layer (analyte) is implemented in the outermost layer, which permits easy and more practical fabrication process compared to analyte is put inside the air holes. It is demonstrated that, at gold layer thickness of 40 nm, the proposed sensor shows maximum sensitivity of 2200 nm/RIU using the wavelength interrogation method in the sensing range between 1.33–1.36. Besides, using an amplitude interrogation method, a maximum sensitivity of 266 RIU−1 and a maximum sensor resolution of 3.75 × 10−5 RIU are obtained. We also discuss how phase matching points are varied with different fiber parameters. Owing to high sensitivity and simple design, the proposed sensor may find important applications in biochemical and biological analyte detection.

https://www.mdpi.com/2304-6732/4/1/18/pdf

A Highly Sensitive Gold-Coated Photonic Crystal Fiber Biosensor Based on Surface Plasmon Resonance

Highly sensitive photonic crystal fiber plasmonic biosensor: Design and analysis

This letter presents a numerical investigation of a highly sensitive refractive index sensor based on surface plasmon resonance. An ultrathin niobium nanofilm is proposed as a new plasmonic material, which outperforms existing plasmonic materials. This nanofilm is employed on a photonic crystal fiber for the first time resulting sensing over a wide range of refractive indices. Finite-element method-based numerical analysis shows that maximum amplitude sensitivity of 1560 RIU $^{-1}$ and wavelength sensitivity of 8000 nm/RIU can be obtained for an analyte index of 1.40. A thin aluminum oxide (Al2O3) film is deposited on the outer layer of niobium film to enhance the coupling strength and in order to tune the resonance wavelength. Moreover, the effects of varying thickness of niobium nanofilm and Al2O3 film on sensing performance are also discussed. The proposed niobium nanofilm based sensor can be potentially implemented in biochemical and organic chemical sensing.

Plasmonic Refractive Index Sensor Employing Niobium Nanofilm on Photonic Crystal Fiber

In this paper, we numerically demonstrate a low-cost plasmonic refractive index sensor using two-sided open-channels that can operate in both visible and near-infrared region. Widely used finite element method (FEM) software is employed to characterize the sensing properties. A thin coating of gold layer is used inside the open channels of the photonic crystal fiber (PCF) to create the plasmons. It is reported that the highest wavelength sensitivity of 5000 nm/RIU with a sensor resolution of 2.0 × 10−5 RIU can be achieved at an analyte refractive of 1.38. Besides, it is also achievable to have the highest amplitude sensitivity of 396 RIU−1. The proposed sensor shows excellent linear characteristics with the highest figure of merit (FOM) of 47 RIU−1 between a refractive index of 1.33 and 1.39. Due to structural simplicity and improved sensitivity, the proposed plasmonic sensor is highly applicable in biological and biochemical analyte detections.

Sanjida Akter

Papers

Spiral Photonic Crystal Fiber-Based Dual-Polarized Surface Plasmon Resonance Biosensor

A Highly Sensitive Gold-Coated Photonic Crystal Fiber Biosensor Based on Surface Plasmon Resonance

Highly sensitive photonic crystal fiber plasmonic biosensor: Design and analysis

Plasmonic Refractive Index Sensor Employing Niobium Nanofilm on Photonic Crystal Fiber

Highly sensitive open-channels based plasmonic biosensor in visible to near-infrared wavelength