Photonic Crystal Fiber Refractive Index Research Articles

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

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

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

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

Photonic crystal fiber refractive index temperature sensor based on double spherical cascade

A dual spherical photonic crystal fiber (PCF) Mach-Zender refractive index temperature sensor is proposed. The sensing structure is a PCF fused to a spherical structure made of two single-mode fibers, of which the two spherical structures serve as beam splitter and coupler, respectively, for refractive index sensing experiments. In addition, temperature sensing experiments were conducted by filling the middle PCF with ethanol using the same structure. Experimental results show a maximum sensitivity of 190.26 nm/RIU for the wavelength drift of the resonance valley of the interference spectrum in the refractive index range of 1.348–1.358. The maximum sensitivity of the wavelength drift of the resonant valley of the interference spectrum is − 0.306 nm/°C for temperatures in the range of 40–50 °C. The sensor studied in this paper is characterized by high sensitivity, simple manufacturing, and low cost.

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.

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.