Photonic Crystal Fiber Refractive Index Research Articles

Photonic Crystal Fiber SPR Liquid Sensor Based on Elliptical Detective Channel.

This paper proposes a Photonic Crystal Fiber (PCF) refractive index sensor model based on the surface plasmon resonance effect. The proposed PCF model also uses the full vector finite element method to transfer the structure under the anisotropic Perfect Matching Layer (PML) boundary condition. Numerical calculations were carried out on the sensor characteristics. The calculation results show that the elliptical air hole on the left side of the PCF core is coated with a gold-nano film which serves as a Surface Plasmon Resonance (SPR) sensing channel to detect the refractive index of liquid materials. Compared with other structures, the resonant peak generated by the excited SPR effect from the elliptical sensing channel has a high sensitivity to the change of the refractive index of the liquid to be measured. With the help of this attribute, it is relatively easy to adjust the sensitivity. The refractive index range of this structure is within 1.43–1.49 and the sensitivity is up to 12,719.97 nm·RIU−1. The linearity is good; R2 = 0.99927, which is very suitable for liquid sensing.

Highly sensitive dual-core symmetrical side-polished modified D-shaped SPR based PCF refractive index sensor with deeply etched micro openings

A novel dual side-polished photonic crystal fiber (DSP-PCF) refractive index (RI) sensor is proposed for the RI detection range of 1.30−1.35. An active plasmonic metal gold (Au) is deposited on a polished flat fiber surface to generate plasmons so that it can detect the change in RIs of its surrounding medium. A thin titanium dioxide (TiO2) layer is coated to assist the adhesion of Au layer with silica-based fiber. To enhance the sensitivity, silicon nitride (Si3N4) is deposited on the top of Au to make it as a dielectric sensing layer. Simulation outcomes demonstrate that the maximum wavelength sensitivity (WS), amplitude sensitivity (AS) and RI resolution reach the highest value of 35,000 nmRIU−1, 350 RIU−1 and 4.347×10-6RIU, respectively, for DSP-PCF. Additionally, the obtained WS for DSP-PCF is far better than the recently reported PCF sensors in the above mentioned RI detection range to the best of our knowledge. With these significant outcomes over the wide analyte RI range, the proposed sensor opens new possible study windows in the field of organic chemicals and biological sensing.

Dual core four open channel circularly slotted gold coated plasmonic biosensor

In this paper, a four open channel dual-core photonic crystal fiber (OC-DC-PCF) refractive index (RI) sensor is numerically investigated by finite element method (FEM) based software for the detection of unknown biomolecules. To create the surface plasmon resonance (SPR) effect, novel plasmonic material gold (Au) is externally deposited to the selected slotted region which makes this design cost-effective. We obtain the maximum wavelength sensitivity (WS) 38000 nm/RIU and the amplitude sensitivity (AS) of 1286 RIU−1 by using wavelength and amplitude interrogation method respectively. The average spectral sensitivity is 6308 nm/RIU. The maximum figure of merit (FOM) of 760 RIU along with the maximum sensor resolution of 2.63×10−6 RIU is achieved within the analyte RI range of 1.33 to 1.45 for this design which is better than the reported existing works. According to its high sensitivity and cost-effective nature, large detection range, high linearity and FOM, low propagation loss, and low fabrication complexity- it can be an appreciable competitor in the region of bio sensing. The proposed sensor can detect successfully the biomolecules like water, ethanol, fused silica, silicone oil, kerosene, acetone, glucose solution, Teflon, cornea, lens, liver and intestinal mucosa of human etc.

A D-Shaped Photonic Crystal Fiber Refractive Index Sensor Coated with Graphene and Zinc Oxide.

A surface plasmon resonance (SPR) sensor based on a D-shaped photonic crystal fiber (PCF) with an uncomplicated structure is proposed to detect the change of refractive index of liquid analytes, and numerical simulation is carried out by the finite element method (FEM). Using silver as the plasmonic metal, the performances of the SPR-PCF sensor coated with a graphene layer and zinc oxide (ZnO) layer were assessed. The sensor designed is only coated with material on the polished surface, which makes the sensor production uncomplicated and solves the problems of filling material in the hole and coating on the hole wall. The effects of structural parameters such as graphene layer thickness, silver layer thickness, ZnO thickness, lattice spacing and manufacturing tolerance of blowhole diameter on the sensor performance were numerically simulated. The numerical results show that the sensitivity of the SPR-PCF sensor coated with 25 nm ZnO is highest in the ZnO thickness range from 10 to 25 nm. In the refractive index range of 1.37–1.41 for liquid analyte, the maximum sensitivity and corresponding resolution reach 6000 nm/RIU and 1.667 × 10−5, respectively. In addition, the sensor has good stability and high structural tolerance under the tolerance of ±5% of blowhole diameter. This work has wide application value in the detection of biochemical analytes, water pollution monitoring, food quality, and medical diagnosis.

Design of Photonic Crystal Fiber Refractive Index Sensor Based on Surface Plasmon Resonance Effect for the Dual-Wavebands Measurement

ABSTRACT In this paper, we propose a photonic crystal fiber (PCF) refractive index (RI) sensor based on the surface plasmon resonance (SPR) effect. The coupling and sensing characteristics of the proposed PCF-SPR RI sensor are investigated by the finite element method. The proposed PCF-SPR RI sensor can achieve the dual-wavebands measurement. By controlling the analytes height and incident light wavelength, the PCF-SPR RI sensor shows different sensing performances. The maximum wavelength sensitivities of the proposed PCF-SPR RI sensors can be up to 2000 and 4000 nm/RIU in the wavelength ranges of 0.75 to 1.0 and 1.2 to 2 μm, respectively.

Highly Sensitive Localized Surface Plasmon Polariton Based D-Type Twin-Hole Photonic Crystal Fiber Microbiosensor: Enhanced Scheme for SERS Reinforcement.

The emerging development of sensing technology initiates innovative sensors achieving low-cost to facilitate practical realization. An interesting crush of the work is to propose a simple structural sensor and to analyze the different schemes of the metal coating by stimulated emission of Raman scattering (SERS) intensification. For the first time, we propose a simple geometrical photonic crystal fiber refractive index based sensor (PCF-RIBS) with three different Schemes A, B, and C, i.e., gold (A) layer-coated surface plasmon resonance (SPR) based D-type PCF-RIBS; Au with titanium-di-oxide (TiO) layer-coated SPR D-type PCF-RIBS; and Au + TiO grating-coated localized surface plasmon resonance (LSPR) D-type PCF-RIBS. Characterizing the three different Schemes A, B, and C using finite element method simulation shows, a maximum wavelength sensitivity of 48,000 nm/RIU, 52,000 nm/RIU and 75,000 nm/RIU, respectively, for a wide range of analyte-refractive index from 1.33 to 1.45 and operates in the wavelength range from 500–2000 nm. Of all the Schemes, Scheme C is found to excite a relatively larger number of surface-plasmons. Eventually, it exhibits improved sensing performances compared to SPR based Schemes A and B. Consequently, it would turn out to be an appropriate candidate to detect a broad range of biological and chemical sample detection.

Detection of cancer affected cell using Sagnac interferometer based photonic crystal fiber refractive index sensor

The light interaction with the cell of any part or organ of the body gives useful information regarding the changes in optical properties for different cells. A photonic crystal fiber, selectively filled by the sample cell is proposed to detect the cancer cell based on the refractive index (RI). Upon considering the change of optical properties of the proposed fiber due to different RI of normal and cancer cell, sensitivities are attained of 11,428.57, 17,142.85, 31,428.57, and 34,285.71 nm/RIU for Jurkat, PC12, MCF-7, and MDA-MB-231 cell from the transmission spectrum obtained by the Sagnac interferometer phenomena.

TiO2/gold-graphene hybrid solid core SPR based PCF RI sensor for sensitivity enhancement

We propose a d-shaped photonic crystal fiber (PCF) refractive index (RI) sensor based on surface plasmon resonance (SPR), capable to work in both visible and near-infrared (NIR) wavelength (410–1790 nm) region. Gold (Au) is deposited on the flat outer surface of the PCF to excite the plasmons. A thin titanium dioxide (TiO2) layer is sandwiched between fiber surface and gold layer so that the gold nanoparticles can strongly attach with the fiber surface. It also helps to shift the resonance wavelength of the proposed sensor to near IR region which is much advantageous for biosensing. A thin graphene layer is applied on Au to assist adsorption of ample biomolecules on its surface. It also prevents gold from oxidation. Simulation results show the theoretical maximum wavelength sensitivity of 48,900 nm/RIU and average sensitivity of 13112.5 nm/RIU in the RI rage of 1.32−1.40. Besides this, the proposed sensor shows the higher amplitude sensitivity of 738.74/RIU with high resolution and maximum figure of merit (FOM) of 7.604×10-6RIU and 611.25/RIU, respectively. These promising outcomes of the proposed sensor make itself to be a potential candidate for the various analyte (organic chemicals, biomolecules) detection. Moreover, the fabrication feasibility of our proposed D-shaped sensor becomes easier than the circular PCF sensors as it avoids the internal coating of the plasmonic metals.

A high linearity refractive index sensor based on D-shaped photonic-crystal fiber with built-in metal wires

We proposed a D-shaped photonic crystal fiber refractive index sensor based on surface plasmon resonance for the detection of refractive-index (RI) liquid analytes between 1.27 and 1.37. In contrast to the common D-shaped structure photonic crystal fiber, three metal wires were added between the D-surface and top level air holes in our design, which prevent the analytes from contacting the metal. It is particularly suitable for detecting some analytes which are easy to react with metal. The sensing performance of D-shaped photonic crystal fiber was studied by the finite element method. Simulation result shows that the sensor has a very good linearity. The adjusted R2 values of resonance wavelengths fitting lines are 0.9996 in 1.27−1.32. The sensitivity of the designed sensor can be as high as 11,500 nm/RIU, and a high resolution of 8.7 × 10−6 RIU is achieved when na = 1.36.An average sensitivity of 8,846.67 nm/RIU in the sensing range 1.27−1.32, and 10,812 nm/RIU in 1.33−1.37 with high linearity is obtained. The D-shaped optical fiber usually realizes the sensing function by coating a metal film, but the method of adding metal wires has rarely been reported before. Owing to the high linearity, high resonance intensity and sensitivity, the proposed sensor can find important applications in environmental, biological and biochemical analytes detection.

Twin core photonic crystal fiber refractive index sensor for early detection of blood cancer

This paper presents a twin-core photonic crystal fiber (TC-PCF) for early detection of blood cancer based on refractive index (RI) of the normal and cancerous blood cell. The samples of the normal and cancerous cells are considered at 30–70% and 80% in liquid form, respectively, and proposed to be infiltrated into the center air hole which is comparatively larger than the others. By considering the refractive index (RI), the change in the coupling length and transmitted spectrum of the proposed TC-PCF for the normal and cancerous cells is observed by using the finite element method (FEM). According to the transmitted spectrum shift, the proposed sensor can exhibit a large sensitivity of 8571.43 nm/RIU. Owing to simple detection mechanism, the proposed TC-PCF sensor can be used for blood cancer detection effectively and cheaply.

Dual-polarized ultrahigh sensitive gold/MoS2/graphene based D-shaped PCF refractive index sensor in visible to near-IR region

We propose a surface plasmon resonance based D-shaped photonic crystal fiber (PCF) refractive index (RI) sensor in visible to near-infrared spectrum. It is suitable for the detection of biomedical/biochemical analytes within the different analyte refractive indices ranging from 1.33 to 1.40. Gold is used as an active metal deposited on the partially removed cladding of the D-shaped PCF. Subsequently, a thin layer of molybdenum disulfide (MoS2) is deposited on the gold because it supports intensive confinement of plasmon polaritons with low loss. Further, a flake of graphene is deposited on MoS2 layer as it provides oxidation resistance to gold and MoS2 layers. MoS2 improves the sensing characteristics of the proposed D-shaped PCF due to its high surface adsorption efficiency and excellent band gap tunability. Moreover, the structure parameter such as the diameter of the largest air hole and the thickness of gold, graphene and MoS2 layer is varied to observe its effect on sensing performance of the proposed PCF. The simulation result showed that the sensitivity was improved and reached to 14,933.34 nm/RIU (refractive index unit) with a high figure of merit and an effective RI resolution of 401.05 RIU−1 and $$6.69\times {10}^{-6}$$ RIU, respectively. With such sensing characteristics, our proposed sensor can be a potential candidate in plasmonic sensors.

A Tunable High-Sensitivity Refractive Index of Analyte Biosensor Based on Metal-Nanoscale Covered Photonic Crystal Fiber With Surface Plasmon Resonance

A tunable high-sensitivity gold-film covered photonic crystal fiber refractive index biosensor based on surface plasmon resonance is proposed. The finite element method is used to analyze and discuss the sensing performance of the biosensor to the analyte. The radio interference (RI) of the analyte is detected by flowing it though the outer fiber surface. The phase matching condition is satisfied between the fundamental mode and the surface plasmon polariton modes, whose resonance coupling can be achieved. The complete coupling and incomplete coupling are excited as the analyte RI increases, and the resonance strength of the complete coupling is stronger than that of the incomplete coupling. It can be proved by calculation that the resonance coupling for the fundamental mode and the fifth-, sixth-, or seventh-order SPP mode has been obtained at different wavelengths. However, the biosensor has obtained four ranges including the analyte RI from 1.33 to 1.38, 1.405 to 1.425, 1.425 to 1.445, and 1.405 to 1.445, respectively. Their average sensitivities are 1971, 8220, 15180, and 5140 nm/RIU, and the linearities are 0.82982, 0.99771, 0.98104, and 0.99837, respectively. In short, the superior performance of tunable, wide-range, and high sensitivity is obtained, which shows a bright application prospect in the field of bio-detection technology.

High-sensitivity photonic crystal fiber refractive index sensor based on directional coupler

A high-sensitivity photonic crystal fiber (PCF) refractive index sensor based on the resonant coupling of core mode and defect mode is studied by the finite element method. The large liquid-filled is placed near to the core for easy coupling with the core mode. The simulation results show that when the refractive index of the analyte is 1.425–1.45 and 1.45–1.46, the average sensitivity is 60,611 and 28,000 nm/RIU respectively, and the corresponding minimum detection limits are 1.58 × 10−6 and 2.86 × 10−6 RIU.

High sensitivity photonic crystal fiber sensor based on dual-core coupling with circular lattice

Abstract A novel high-sensitivity circular dual-core photonic crystal fiber refractive index sensor is proposed in this paper. The effects of air hole spacing, liquid filled air hole diameter and cladding air hole diameter on its sensor sensitivity are analyzed in detail. The simulation results show that the liquid refractive index that the sensor can detect ranges from 1.33 to 1.41. By optimizing the geometric parameters, when the analyte refractive index is 1.33 and 1.41, respectively, the minimum sensitivity of this PCF sensor is 8929 nm/RIU, and the maximum value can reach 22071 nm/RIU. Due to its high sensitivity and simple structure, this PCF sensor can be widely used for chemical detection and biomolecule detection.

High Sensitivity Photonic Crystal Fiber Refractive Index Sensor with Gold Coated Externally Based on Surface Plasmon Resonance.

In this paper we propose a gold-plated photonic crystal fiber (PCF) refractive index sensor based on surface plasmon resonance (SPR), in which gold is coated on the external surface of PCF for easy fabrication and practical detection. The finite element method (FEM) is used for the performance analysis, and the numerical results show that the thickness of the gold film, the refractive index of the analyte, the radius of the air hole in the first layer, the second layer, and the central air hole can affect the sensing properties of the sensor. By optimizing the sensor structure, the maximum wavelength sensitivity can reach 11000 nm/RIU and the maximum amplitude sensitivity can reach 641 RIU−1. Due to its high sensitivity, the proposed sensor can be used for practical biological and chemical sensing.

Ultrahigh sensitivity refractive index sensor of a D-shaped PCF based on surface plasmon resonance.

We propose a D-shaped photonic crystal fiber (PCF) refractive index sensor with ultrahigh sensitivity and a wide detection range. The gold layer is deposited on the polished surface, avoiding filling or coating inside the air holes of the PCF. The influences of the gold layer thickness and the diameter of the larger air holes are investigated. The sensing characteristics of the proposed sensor are analyzed by the finite element method. The maximum sensitivity can reach 31,000 nm/RIU, and the refractive index detection range is from 1.32 to 1.40. Our proposed PCF has excellent sensing characteristics and is competitive in sensing devices.

Surface Plasmon Resonance Sensor Based on a Novel D-Shaped Photonic Crystal Fiber for Low Refractive Index Detection

A novel D-shaped photonic crystal fiber refractive index sensor based on surface plasmon resonance (SPR) is proposed and numerically studied. Different from the normal D-shaped structures, we here used an open-ring channel coated with gold film to excite the plamonic modes. The coupling properties and sensing performance of this structure are analyzed using finite element method. Simulation results indicate that the sensor has a sensing range from 1.20 to 1.29. When the analyte refractive index (RI) is above 1.25, the anti-crossing effect starts to appear, and the peak loss of the loss spectra remains nearly constant with increasing RI. The maximum spectral sensitivity of 11055 nm/RIU and high resolution of $9.05\times 10^{-6}$ RIU can be obtained at 1.29. For the purpose of optimizing sensing performance, the effects of the structure parameters on the resonant spectra are also studied. The excellent sensing performance makes the proposed SPR sensor a competitive candidate in low refractive index detection applications.

D-shaped photonic crystal fiber refractive index sensor based on surface plasmon resonance.

A type of D-shaped photonic crystal fiber sensor based on surface plasmon resonance (SPR) is proposed for refractive index sensing and analyzed by the finite element method. The SPR 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. Numerical results show that the sensor can detect a range of refractive index ranging from 1.33 to 1.38. When the thickness of metal film is t=20 nm, the maximum sensitivity of 10,493 nm/RIU is obtained with a very high resolution of 9.53×10-6 RIU. The good sensing performance makes the proposed sensor a competitive candidate for environmental, biological, and biochemical sensing applications.

Design of a surface plasmon resonance refractive index sensor with high sensitivity

This paper presents a highly sensitive photonic crystal fiber (PCF) refractive index sensor based on the surface plasmon resonance (SPR) effect operating in the telecommunication wavelengths. Gold is used as the plasmonic material due to its chemical stability and titanium dioxide (TiO2) is used to shift the resonance wavelength in the telecommunication bands. Both materials are deposited sequentially on the PCF surface, which is comparatively easy to fabricate. Numerical investigations show that the proposed sensor exhibits very high wavelength sensitivity of 10,800 nm/RIU and amplitude sensitivity of 514 RIU−1 in the sensing range between 1.46 and 1.48. Moreover, it exhibits maximum sensor resolution of 9.25×10−6 RIU and high linearity over a wide sensing range. The proposed sensor can be practically realized due to its simple and straightforward structure.

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

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 sensor, two gold wires obtained by chemical reaction are filled in two air holes between the upper and lower channels. Numerical results show that the refractive indexes of the analytes can be detected from 1.30 to 1.79. It’s a very broad detection range that is rarely seen in the field of photonic crystal fiber sensor based on surface plasmon resonance. The average sensitivity of this photonic crystal fiber could be 100 nm/refractive index unit (RIU) in the dynamic index range from 1.30 to 1.63. In the range from 1.63 to 1.79, the highest sensitivity could reach to 3233 nm/RIU. The ability to integrate four large-size microfluidic channels for efficient analyte flow in is attractive for the development of integrated highly sensitive PCF-SPR sensors.