Crystal Fiber Refractive Index Sensor Research Articles

Refractive index sensing characteristics of PCF-SPR based on dual-plasmon materials

Abstract In this paper, a photonic crystal fiber (PCF) refractive index sensor based on surface plasmon resonance (SPR) with dual plasmonic materials (indium tin oxide and gold) is proposed. We innovatively designed a dual-core PCF structure and pore arrangement effectively enhancing the coupling effect. Using two different plasma materials, phase matching is achieved at two different wavelengths for the evanescent and surface plasmon waves, resulting in dual resonance peaks. The refractive index sensing is accomplished by measuring the dual-peak resonance shift, which expands the detection wavelength and RI detection ranges. The sensor can detect analytes with refractive indices ranging from 1.32 to 1.43 at wavelengths between 0.4 um and 1.4 um. We optimized the photonic crystal fiber structure and studied the sensing performance of the sensor, improving its sensitivity. Simulation results indicate that the designed PCF sensor exhibits outstanding maximum dual-peak shift sensitivity (DPSS), reaching up to 28,000 RIU-1, along with maximum amplitude sensitivity (AS) and wavelength sensitivity (WS) of 18,500 RIU-1 and 34,500 RIU-1, respectively, in the direction of y-polarization. Furthermore, the sensor achieves high resolution, and the figure of merit (FOM) values can reach up to 5.134×10-7 and 2758. Consequently, the proposed sensor can provide high-precision and extensive-range measurements of solution refractive indices within the visible and infrared light spectrum, and it holds potential application prospects in numerous fields, such as food safety testing and chemical substance detection.

Optimization of highly sensitive three-layer photonic crystal fiber sensor based on plasmonic

In this work, a photonic crystal fiber (PCF) refractive index (RI) sensor has been designed and optimized. The RIs range covered by the sensor is from 1.38 to 1.41. The proposed optical sensor has three layers of air holes with 24, 12 and 6 holes in each layer. The geometry parameters of the proposed sensor (the radius of the air holes and the thickness of the plasmonic layer) have been optimized using the Nelder-Mead algorithm and the FEM numerical with the objective of achieving the highest sensitivity. To achieve an optimized structure with minimal sensitivity to fabrication errors, the rotation angle of the hole layers has been analyzed. The results indicate that, due to the specific geometry of the proposed structure, variations in the rotation angle and displacement of the air holes have no significant impact on the outcomes. The results also indicate that the sensor’s maximum amplitude sensitivity (AS), maximum wavelength sensitivity (WS), and figure of merit (FOM) are 10000 (RIU−1), 23000 (nm/RIU) and 131 (RIU−1) respectively. The optimized design provides high sensitivity, a wide diagnostic range for the detection of the analytes’ RIs, and the advantages of a gold plasmonic layer, ensuring high stability in biological environments. This combination results in enhanced performance of the sensor for various applications particularly in biosensing and medical fields. The designed structural geometry also eliminates the effects of tolerances in manufacturing processes which makes the proposed PCF device a very efficient sensor.

Simulation analysis of a photonic crystal fiber refractive index sensor based on a double-layer film structure and surface plasmon resonance technology

A photonic crystal fiber surface plasmon resonance sensor based on a double-layer membrane structure is designed and analyzed. In the simple sensing structure with only one air hole size, TiO2 and Au layers with specific thicknesses are sequentially coated on the optical fiber to form a double-layer structure. The sensing characteristics of the double-layer membrane structure are studied by the finite element method. Compared to the single-layer membrane structure, the double-layer membrane sensor has significant sensing properties such as a better wavelength sensitivity and a smaller full width at half maximum in the loss spectrum. In the refractive index range between 1.37 and 1.43, the maximum wavelength sensitivity and average wavelength sensitivity of the sensor are 19,900 nm/RIU and 7417 nm/RIU, respectively, and the resolution can be up to 5.03×10−6RIU. The proposed photonic crystal fiber optic sensor achieves high performance with a simpler sensing structure than previous photonic crystal fiber optic sensors, and eliminates the step of polishing, which will greatly reduce the difficulty of actual fabrication and the error due to uneven polishing. The results show that the photonic crystal fiber optic sensor with a double-layer membrane structure has excellent performance. Due to its high sensitivity and resolution, it has great potential for applications in environmental monitoring, biosensing and chemical sensing.

Gold-coated D-shaped photonic crystal fiber refractive index sensor with a wide detection range and large manufacturing tolerance

A D-shaped photonic crystal fiber refractive index (RI) sensor is designed, and its performance is analyzed using the finite element method (FEM). A gold film is coated on the D-shaped surface of the fiber as a plasmonic material for surface plasmon resonance sensing. The U-shaped arrangement of holes of the same size in the fiber structure enhances the coupling resonance between the core mode and the surface plasmon polariton mode. Numerical results show that the RI range of the sensor is 1.20–1.40, the maximum wavelength sensitivity is 16008.98 nm/RIU, and the detection width is up to 0.2 RIU. In addition, this study analyzes the manufacturing tolerance for the sizes of the air holes. The results show that the manufacturing tolerance for the three types of air holes is as high as 25%, 11.1%, and 10.2% when h is 40µm. These findings lay the foundation for the mass production of sensors. The above results indicate that the sensor has remarkable advantages such as enhanced sensitivity, wide measurement range, and exceptional manufacturing stability, and has promising applications in the fields of bio-detection, drug supply detection, and water pollution control.

A novel D-shaped photonic crystal fiber refractive index sensor based on surface plasmon resonance effect

A novel D-shaped photonic crystal fiber refractive index sensor based on surface plasmon resonance effect

D-type photonic crystal fiber refractive index sensor based on Bloch surface waves

Bioassays are important in health assessment, disease diagnosis, treatment monitoring, disease prevention, and environmental monitoring to provide better health management and quality of life for individuals and society. A D-type photonic crystal fiber optic sensor based on Bloch surface waves is proposed for biological detection within an ultra-wide refractive index. The designed D-type fiber was side-polished and alternately deposited with one-dimensional photonic crystals (1DPCs) on the polished side, consisting of a set of TiO2 and SiO2 alternating media with moderate refractive index differences. The designed PCF consists of symmetric air holes and polished structures. The structural parameters of this sensor are also analyzed and discussed in order to obtain better detection performance. The designed Bloch surface wave D-type photonic crystal fiber optic sensor has a maximum refractive index sensitivity of 5400 nm/RIU and a maximum amplitude sensitivity of 513.00RIU−1. The sensor also has a resolution of 1.85×10−5RIU and an excellent maximum quality factor (FOM) of 222.43RIU−1. These results show a higher figure of merit (FOM) than conventional methods, resulting in increased sensitivity and accuracy. The proposed sensor can detect the RI of unspecified analytes between 1.20 and 1.50, allowing for the analysis of many different types of analytes, such as viruses, blood plasma, cancer cells, sugars, proteins, DNA/RNA, and many more.

D-type photonic crystal fiber refractive index sensor with ultra-high fabrication stability and ultra-wide detection range

D-type photonic crystal fiber refractive index sensor with ultra-high fabrication stability and ultra-wide detection range

Design of a New Type of In-Hole Gold-Coated High-Performance Quasi-PCF Sensor Enhanced with Surface Plasmon Resonance

With the development of aerospace, deep-sea exploration and other technologies, the demand for anti-electromagnetic, high-sensitivity and miniaturized sensors is increasingly urgent. In this paper, a model of a quasi-photonic crystal fiber (Q-PCF) refractive index (RI) sensor enhanced with surface plasmon resonance (SPR) is proposed. A stable gold film with a significant SPR effect is applied to the two identically sized and oppositely positioned air holes of the proposed sensor, and all air holes are filled with analyte. A detailed analysis of the mode characteristics, structural parameters and RI sensing performance of the sensor has been carried out using the finite element method. It has been shown that the maximum sensitivity (S) is 4977.59 nm/RIU in the RI range of 1.35–1.40, corresponding to a resolution (R) of 2.01 × 10−5 RIU and a figure of merit (FOM) of 160.36 RIU−1. The proposed Q-PCF sensor has unique fabrication advantages and outstanding sensing properties, providing a new idea for biosensing, complex environment monitoring and long-range measurement, and is of great practical value in the field of highly integrated sensing.

High sensitivity photonic crystal fiber temperature and refractive index sensor based on surface plasmon resonance

High sensitivity photonic crystal fiber temperature and refractive index sensor based on surface plasmon resonance

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

Photonic crystal fiber refractive index sensor based on SPR

Photonic crystal fiber refractive index sensor based on SPR

Design and analysis of surface plasmon resonance sensor based on multi-core photonic crystal fiber

A three-core photonic crystal fiber refractive index sensor based on the surface plasmon resonance effect is proposed. The three cores of this sensor are symmetrical about the center. The gold film deposited outside the fiber structure makes this sensor contact with the analyte directly, which not only reduces the complexity of the fabrication but also makes the limiting loss very low. The sensing performance of the proposed sensor is investigated by using the finite element method. Numerical results show that the loss spectra of the x-polarized core mode are consistent with the y-polarized core mode. The sensor realizes the sensing detection of the analyte refractive index ranging from 1.37 to 1.42. When the analyte’s refractive index is 1.42, the maximum wavelength sensitivity of 2427 nm/RIU for x and y polarization, the corresponding maximum resolution can reach 4.12 × 10−5 RIU.

A novel photonic crystal fiber refractive index sensor with ultra wide detection range based on surface plasmon resonance effect

In this paper, a novel photonic crystal fiber (PCF) refractive index (RI) sensor based on surface plasmon resonance (SPR) effect is proposed. With the full vector finite element method, the SPR-PCF RI sensor is designed, and the mode coupling effects between the X-polarization (X-pol) and Y-polarization (Y-pol) core modes and second-order surface plasmon polariton modes are analyzed. The simulation results show that the structure parameters of the proposed PCF have significant influences on the resonance wavelength drift and wavelength sensitivity (WS). Finally, in the RI range of 1.32 ~ 1.48, the average WSs of the X-pol and Y-pol core modes can reach − 4735.83 nm/RIU and − 4525.83 nm/RIU, respectively. Moreover, the maximum resolution (R) and figure of merits (FOM) of the X-pol and Y-pol core modes are 4.71 × 10−6 and 4.65 × 10−6 RIU, and 134 and 177 RIU−1, respectively. Compared with other reported results, the proposed SPR-PCF RI sensor can achieve wide detection range, high average WS, good linearity, high R, and large FOM, so it will have important applications in the fields of biochemistry, medicine, and environmental science.

Double-sided photonic crystal fiber (PCF) temperature and refractive index (RI) sensor based on surface plasmon resonance (SPR)

A double-sided photonic crystal fiber (PCF) temperature and refractive index (RI) sensor based on surface plasmon resonance (SPR) is reported to simultaneously measure temperature and RI. An arc groove covered with gold is filled with chloroform for temperature detection. The D-shaped plane coated with silver is in direct contact with the analyte to provide the RI. Two independent channels distinguish temperature and RI changes, thus completely solving the cross-sensitivity problem. The sensing characteristics of the plane coating, arc coating, and inner ring coating are discussed. The influence of gold film closure on the optimum RI measurement range was identified, and the best sensing structure of chloroform as a temperature-sensitive material is obtained. The sensing characteristics of different types of metal films are investigated. It is concluded that the band separation may be achieved by plating gold film and silver film in the arc groove and D-plane, respectively. The influence of the central angle of the arc groove on the sensor characteristics was investigated. High-order resonance may be avoided at a 180° center angle. The influence of the thickness of the metal film on the sensitivity of the sensor is studied numerically, and the optimal coating thickness is 50 nm. This work simplifies the selection of the RI range of sensing materials and provides a new approach to solve the high-order resonance and band interference in SPR multi-parameter sensors.

Surface plasmon resonance (SPR)-based D-shaped photonic crystal fiber polarization filter and refractive index sensor with a hexagonal pore structure

A D-shaped photonic crystal fiber (PCF) polarization filter and sensor with a standard hexagonal arrangement of pores is designed. The effects of geometric parameters, metal film thickness, liquid refractive index, and optical material refractive index on polarization filtering and sensing characteristics are analyzed by the finite element method (FEM). The proposed PCF shows single-polarization filtering in communication window and has ultra-high corresponding bandwidth. At the 1.55 µm communication window band, the confinement loss of the y-polarized core mode is 819.27 dB/cm, while the x-polarized core mode is only 3.45 dB/cm. The crosstalk (CT) reached a maximum of 708.6 dB in the communication bands, and the corresponding bandwidth reaches 1000 µm when the fiber length is 1 mm. Meanwhile, the D-type PCF is widely used in sensing because it avoids filling the gold film and analyte in the internal pores. The change in the thickness of the mental coating from 39 nm to 22 nm provides the proposed PCF with sensing properties. By reducing the refractive index of fiber material, the maximum sensitivity is 10,741 nm/RIU. When the refractive index measurement range of the analyte is specified from 1.33 to 1.36, the average sensitivity reaches 7313 nm/RIU. Good performance enables the proposed compatible filtering and sensing PCF may be used in a wide range of scenarios.

A novel surface plasmon resonance-based photonic crystal fiber refractive index sensor with an ultra-wide detection range

In this paper, a novel photonic crystal fiber (PCF) refractive index (RI) sensor with an ultra-wide detection range based on the surface plasmon resonance (SPR) effect is proposed. By selectively filling the air hole with the analyte and introducing the gold-coated air hole, the high performance RI sensing can be achieved. The simulation results show that the asymmetric structure of the PCF makes the x-polarization (x-pol) and y-polarization (y-pol) core modes have different sensing characteristics. The average wavelength sensitivity of the proposed SPR-PCF RI sensor can reach − 4523 nm/RIU in the RI range from 1.25 to 1.45 for the x-pol core mode as well as − 4851 nm/RIU in the RI range from 1.25 to 1.49 for the y-pol core mode. The maximum amplitude sensitivities of − 1239.19 RIU−1 and − 1633.54 RIU−1 for the x-pol and y-pol core modes are also achieved. Moreover, the proposed SPR-PCF RI sensor can obtain the maximum resolutions of 1.603 × 10−5 and 1.695 × 10−5 RIU and figure of merits of 226.92 and 105.76 RIU−1 for the x-pol and y-pol core modes, respectively. It is believed that the proposed SPR-PCF RI sensor has potential applications in the chemistry, biology, and environment monitoring.

High-sensitivity refractive index sensor with cascaded dual-core photonic crystal fiber based on vernier effect

A cascaded dual-core photonic crystal fiber (DC-PCF) refractive index sensor is proposed. The sensor is composed by cascading a single-mode fiber with a DC-PCF, thus realizing the vernier effect. The central air hole of the DC-PCF is filled with different refractive indices. The refractive index sensitivity is investigated using the full vector finite element method (FEM). The simulation results show that the cascade structure of the DC-PCF with three different air hole diameter parameters has high sensitivity up to −303376 nm/RIU in the refractive index range of 1.362–1.366, and the highest sensitivity of the cascade corresponds to a resolution of 3.30 × 10−7. The sensitivity is increased by 37 times compared to the DC-PCF without vernier effect.By replacing the central air hole material, the sensor can be used for temperature sensing, magnetic field sensing and water quality analysis.

Polished photonic crystal fiber refractive index sensor based on surface plasmon resonance

A polished photonic crystal fiber sensor based on surface plasmon resonance for refractive index (RI) detection is proposed and analyzed by finite element analysis. The design of polishing can greatly increase the birefringence of photonic crystal fiber and ensure a uniform coating film, thus improving sensor performance. The outer air of the structure is arranged in half of an octagonal shape, and the inner layer is arranged in a quadrilateral shape, which can effectively improve coupling strength in the y -polarization direction. The sensor works mainly in visible and infrared wavelengths with a detection range of 1.33 to 1.38. Through analysis of external RI changes, pore structure parameters, and silver mold thickness, the maximum sensitivity is 14800 nm/RIU, maximum amplitude sensitivity is 766.7008 R I U − 1 , resolution is up to 6.7568 × 10 − 6 R I U , and maximum figure of merit is 548.1481. The sensor is suitable for biomedicine, environmental monitoring, chemistry, and other fields.

High sensitivity refractive index sensor based on triple layer MgF2-gold-MgF2 coated nano metal films photonic crystal fiber

A high sensitivity triple layer photonic crystal fiber (PCF) refractive index (RI) sensor based on surface plasmon resonance (SPR) is proposed for RI analytes sensing. As a plasmonic material, a nanofilm gold layer with two MgF2 layers is used that assists to achieve high sensitivity, larger birefringence, maximum resolution and high transmittance profile. The entire analysis and sensing performance of this proposed structure is done by using the finite element method (FEM) for 1.7 µm to 3.7 µm wavelength. The highly SPR sensitive RI analytes are injected into the outmost air holes of the cladding where fused silica is served as the base material. The highest wavelength sensitivity response of 28,046.205 nm/RIU is obtained at RI analytes 1.38. The maximum resolution, birefringence and transmittance variance are 3.94 × 10−5 RIU, 3.59 × 10−4 and −45.80 dB respective in the RI analytes range 1.32–1.38. The outstanding sensing performance suggests the proposed triple layer PCF sensor as a promising candidate in the field of RI analyte sensing.

A High‐Sensitivity Refractive Index Sensor Based on an External Gold Coating of a Square‐Lattice Photonic Crystal Fiber

A high‐sensitivity square‐lattice photonic crystal fiber (PCF) refractive index (RI) sensor based on an external gold coating is proposed. This design eliminates the limitations of selective coating and liquid penetration in the micrometer holes, and avoids the side polishing of D‐type fibers. The effects of air hole diameter and gold film thickness on the sensing performance are studied in detail using the full vector finite element method (FV‐FEM). In addition, the sensing performance of the gold‐coated PCF under the optimized parameters is compared with that of PCF with the same air hole diameter and a gold grating. The results show that the proposed PCF has a higher structural tolerance to the air hole diameter, which improves the manufacturing feasibility. Moreover, the gold‐coated PCF has a maximum sensitivity of 31 000 nm RIU−1 and a resolution of 3.23 × 10−6 RIU in the RI measurement range of 1.34–1.49. The maximum sensitivity of the gold‐grating PCF with lower loss is 30 000 nm RIU−1 in the RI detection range of 1.38–1.46, and the resolution is 3.33 × 10−6 RIU. Low loss is beneficial for extending the length of the fiber, which is convenient for practical implementation. Thus, it has potential applications in biomolecular and biochemical analysis.