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This paper presents a dual-core two-parameter optical fiber sensor based on the surface plasmonic resonance (SPR) effect. It is analyzed by the finite element method. The proposed sensor is a dual-channel structure designed with photonic crystal fiber (PCF) as the base material: one channel is coated with a gold film to measure the refractive index (RI) of the solution to be measured, and the other channel is coated with a gold film and polydimethylsiloxane to measure the temperature of the solution to be measured. The exposed microslot structure on both sides reduces the complexity of sensing measurements. The results show that the maximum RI sensitivity of the sensor is 19,900 nm/RIU, and the maximum sensitivity to temperature is 8.7 nm/℃. This work is conducive to realizing a PCF sensor with high sensitivity, large measurement range, real-time monitoring, and easy preparation. As a result, the sensor is expected to be widely used in fields such as biology and chemicals. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) sensing methods enable highly sensitive, fast response, and label-free analysis of biomolecular interactions. For SPR sensors, sensitivity and full width at half maximum (FWHM) are two incompatible performance parameters. We propose a refractive index (RI) sensor using a dual-core photonic crystal fiber (PCF) and SPR effects to achieve high sensitivity and a narrow FWHM simultaneously. The air holes of the sensor appear in a hexagonal arrangement, and polishing technology introduces two polishing planes into the cladding. A gold film is deposited on one side of the polished plane to form a highly sensitive RI sensing channel. Five gold nanowires are deposited on the other side of the polished plane to form a RI sensing channel with a narrow FWHM. We analyzed and optimized its structural parameters using the finite element method and determined the optimal structural parameters. The numerical results demonstrate that the maximum sensitivity of the sensor is 21,000 nm/RIU with the narrowest FWHM of 31 nm. Therefore, measuring the refractive index simultaneously with two sensing channels increases the detection accuracy of the measurement. In addition, the findings further indicate that variations in structural parameters do not significantly impact the sensing performance of the sensor, which makes the production of the sensor relatively simple. In conclusion, our work provides a new research method for realizing high sensitivity and a narrow FWHM simultaneously. [ABSTRACT FROM AUTHOR]

A D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor is proposed to measure the refractive index in visible and near-infrared regions. Compared with traditional PCF, the use of D-shaped PCF can avoid filling materials and coatings in the hole. The plasma material of sensors is silver, and graphene is coated on the surface of the silver film. Graphene layer can not only prevent the oxidation of the silver but also improve the performance of the sensor. Then the influence of structural parameters on the sensor performance is studied by the finite element method (FEM). Results show that the performance of the sensor is not sensitive to the structural parameters, which makes the sensor has a good manufacturing tolerance. Moreover, when the refractive index (RI) of the analyte is 1.33 ~ 1.41, the maximum wavelength sensitivity is 13,750 nm/RIU, and the corresponding RI resolution is 7.27 × 10−6 RIU−1. In addition, the maximum figure of merit is 201 RIU−1. The proposed sensor is advanced with high sensitivity, simple structure and big fabrication tolerance, which could become a competitive candidate for water pollution monitoring, medical diagnosis, biochemical analysis, and detection fields. [ABSTRACT FROM AUTHOR]

In this paper, we propose a broadband mode converter based on photonic crystal fiber (PCF) starting from the method of propagation constant height fitting. Using the finite element method and the beam propagation method, three typical mode converters in the S + C + L range, LP01 to LP11, LP01 to LP21, and LP01 to LP31, are calculated. Numerical results show that the mode coupling efficiency of this mode converter is over 90% and the mode extinction ratio is over 10 dB. This converter can realize pattern multiplexing in a cascade manner. On this basis, we propose a multi-core mode multiplexer structure. On the premise of sacrificing some performance, three modes can be reused at the same time. Mode converters of PCF structure can be fabricated by PCF post-processing technology. It is expected to become an important part of the future mode division multiplexing (MDM) optical communication system. [ABSTRACT FROM AUTHOR]

A high sensitivity plasmonic temperature sensor based on a side-polished photonic crystal fiber is proposed in this work. In order to achieve high sensitivity and high stability, the gold layer is coated on the side-polished photonic crystal fiber to support surface plasmon resonance. The mixture of ethanol and chloroform is used as the thermosensitive liquid. The performances of the proposed temperature sensor were investigated by the finite element method (FEM). Simulation results indicate that the sensitivity of the temperature sensor is as high as 7.82 nm/°C. It has good linearity (R 2 = 0.99803), the resolution of 1.1 Ă— 10âˆ'3 °C, and the amplitude sensitivity of 0.1008 °Câˆ'1. In addition, the sizes of the small air hole and polishing depth have little influence on the sensitivity. Therefore, the proposed sensor shows a high structure tolerance. The excellent performance and high structure tolerance of the sensor make it an appropriate choice for temperature measurement. [ABSTRACT FROM AUTHOR]

An ultra high-sensitivity temperature and refractive index (RI) sensor based on surface plasmon resonance (SPR) effect in D-shape high birefringence photonic crystal fiber (PCF) is presented and discussed by the finite element method (FEM). The designed PCF is polished to enhance the interaction of the evanescent field with the external medium, ultimately improving the sensing performance. The influence of three different plasma materials, gold, silver and aluminum, on the sensing performance was investigated. Finally, the chemically stable plasma material gold is selected to coat on flat surface of D-shape PCF for SPR sensing, realizing the sensitive real-time monitoring of RI and temperature. The sensing performance was greatly improved, with a wide RI (1.43 to 1.50) and temperature (36 $^{\circ }$ C to 86 $^{\circ }$ C) detection range, and the corresponding maximum sensitivity was 44850 nm/RIU and −16.875 nm/ $^{\circ }$ C, respectively. Furthermore, the sensitivity is not particularly sensitive to the sizes of the designed air holes, which leads to a sensor with high structure tolerance. Numerical results show that the coating thickness not only affects the sensitivity but also the detection range of the sensor, so we can tune the RI and temperature detection range by adjusting the gold film thickness to meet specific detection requirements. The sensor with enhanced sensitivity, tunable detection range, and high fabrication tolerance has a wide application prospect in the field of life science research, chemical production, and environmental monitoring. [ABSTRACT FROM AUTHOR]

A magnetic field sensor based on a Sagnac interferometer using a magnetic fluid-filled birefringent photonic crystal fiber (MF-BPCF) was proposed and studied by finite element method. Two large air holes in the birefringent photonic crystal fiber were designed to fill with magnetic fluid. The MF-BPCF in the proposed Sagnac interferometer acted as the sensing head. As magnetic field perpendicular to the MF-BPCF, magnetic fluid was anisotropic. The characteristics of the output spectrum of the Sagnac interferometer was simulated. The results showed that when the phase difference $\phi$ satisfied integer multiples of $2\pi$ , several dip wavelengths appeared. Not only the intensity but also the direction of the magnetic field was measured. The measuring sensitivity could be further promoted by making the dip wavelength approach $\lambda _{B_g=0}$. [ABSTRACT FROM AUTHOR]

An elliptical photonic crystal fiber (PCF) polarization filter based on surface plasmon resonance is proposed. Two smaller elliptical air-holes are selectively filled with gold wires to improve the filter characteristics by the surface plasmon effect. The transmission characteristics and influence of structural parameters are analyzed by the finite-element method. Research shows that the loss of y-polarization is much greater than that of x-polarization. The air holes filled with gold have the greatest influence on the loss of PCF, and the air holes around the fiber core have the greatest effect on the dispersion. In the optimized model, the loss of y-polarization is 333.84 dB/cm, but the loss of x-polarization is only 1.5 dB/cm at 1.55 $\mu \text{m}$. Besides, when the length fiber is $L= 3$ mm, the extinction ratio is 866 dB, and the bandwidth can reach 500 nm, which embodies high extinction ratio and wide bandwidth of this filter. [ABSTRACT FROM AUTHOR]

We propose a modified design for a photonic crystal fiber (PCF) polarization filter based on surface plasmon resonance (SPR). The air holes are arrayed in diamond lattices, and the diameter of the holes around the gold-coated holes are different that can separate the refractive index of the x-polarization and y-polarization second order surface plasmon polariton (SPP) modes. The influences of structural parameters of the photonic crystal fiber (PCF) on the filter characteristics are studied using the finite element method (FEM). Great changes have taken place in the results of numerical simulation by changing the thickness of the gold film and air hole diameter. Simulation results show that the resonance wavelength is communication wavelength 1550 mm, the loss of the y-polarization mode is 43,126.7 dB/m. When the length of the fiber is 500 μm, extinction ratio is more than 20 dB at the communication wavelength, and bandwidth achieve to 190 nm. It is an important property of PCF polarization filter in production. [ABSTRACT FROM AUTHOR]

A broad bandwidth polarization filter based on photonic crystal fiber (PCF) coated with gold layer is proposed and simulated by the full vector finite element method. The surface plasmon resonance coupling theory is studied, and the factors that affect the polarization filtering effect are analyzed. By changing the structural parameters of the PCF, we realize polarization filter at 1.55 and 1.48 μm. In the designed polarization filter, the maximum loss of the unwanted y-polarization at 1.55 μm is 803.56 dB/cm and at 1.48 μm is 732.69 dB/cm. Besides, a broad bandwidth of 1000 nm with the crosstalk better than 20 dB is obtained. The suggested PCF is competitive for polarization device. [ABSTRACT FROM AUTHOR]

We propose a modified design for a Core shift photonic crystal fiber (PCF) polarization filter based on surface plasmon resonance. The Core shiftting is achieved by the air holes with different diameters around the gold-coated holes, which can separate the refractive index of the x-polarization and y-polarization second order surface plasmon polariton modes. The influences of structural parameters of the PCF on the filter characteristics are studied using the finite element method. Simulation results great changes have taken place in the results of numerical simulation by changing the thickness of the gold film and air hole diameter. We obtain a resonance wavelength with 1550 nm. The y-polarization mode is supressed significantly with the loss of 58,456.7 dB/m. With the length of the fiber is 300 μm, a extinction ratio is higher than 20 dB and a bandwidth achieve to 450 nm at the communication wavelength can be got. All these properties we achieved in the core shift PCF are important properties of PCF in broadband polarization filter in application. Our design can offer some guidance to the production of the polarization filter. [ABSTRACT FROM AUTHOR]

A kind of polarized filtering photonic crystal fiber (PCF) with nanoscale gold film is studied by using the finite element method. The cross-section structure of the PCF is composed of a hexagonal lattice of air holes in which an air hole is gold coated, and the air-hole layout is modified. By our structure, the loss of x-polarized mode is further larger than the loss of y-polarized mode and the loss peak appears at the wavelength 1.31 μm. The corresponding loss in x-polarized can reach a value of 85,780 dB/m at the resonance wavelength. It can be used for the communication windows of 1.31 μm which can be used for carrying data/voice. When the length of fiber is longer than 30 μm, the extinction ratio is better than 20 dB at the wavelength 1.31 μm. When the length of fiber is longer than 210 μm, the extinction ratio is better than 20 dB with the wavelength ranging from 1.26 to 2 μm. The broadband polarized filtering PCF covering 740 nm is achieved. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A polarization splitter based on dual-core photonic crystal fiber filled with tellurite glass in the central hole is proposed. The characteristics are studied by finite element method. The influences of the parameters $$d_{1}, d_{2}, \varLambda$$ on the coupling length and coupling length ratio (CLR) are analyzed. The curves of coupling lengths of X-polarization, Y-polarization light dependence on the operable wavelength $$\lambda$$ are flat under the optimized structural parameters which is helpful to realize broadband polarization splitter. The simulation results indicate that the CLR could reach to 2.006 at the wavelength of $$1.55\,\upmu {\hbox {m}}$$ . The fiber length is only 510 $$\upmu {\hbox {m}}$$ and the bandwidth of extinction ratio greater than 20 dB is 284 nm, i.e., from 1461 to 1745 nm which could be widely used in the large-capacity, broad-bandwidth and integrated optical communication systems. As the fiber length decreases, we find the bandwidth increases. But the extinction ratio at 1.55 $$\upmu {\hbox {m}}$$ is lower than 20 dB as the fiber length is less than 510 $$\upmu {\hbox {m}}$$ . [ABSTRACT FROM AUTHOR]

We design two kinds of plasmonic broadband polarization splitters based on dual-core photonic crystal fiber (DC-PCF) with elliptical Au or Ag nanowire in this paper. It is analyzed for the polarization independent characterestics of the designed DC-PCF by the finite element method (FEM). In order to excite the surface plasmon resonance (SPR), the metal Au and Ag are filled into elliptical central air hole. The resonance coupling between the fourth- or fifth-order surface plasmon modes (SPMs) and core-guided modes (CGMs) are founded by this numerical simulation. The device lengths of the designed splitters with Au nanowire are 2937 and 827 μm at the wavelength of 1.31 and 1.55 μm, respectively. As the extinction ratios are better than −20 dB, its bandwidths are better than 94 and 103 nm. For the designed Ag nanowire splitter, the device lengths are 3066 or 809 μm at 1.31 or 1.55 μm, respectively. The bandwidths with the extinction ratio better than −20 dB are 66 and 104 nm, respectively. [ABSTRACT FROM AUTHOR]

The filtering characteristics and applications of photonic crystal fibers being selectively infiltrated with one aluminum rod were investigated based on the finite-element method. The aluminum rod being selectively infiltrated into one cladding air hole acted as a defect core and generated surface plasmon polaritons on its surface. As the phase matching condition was satisfied, the light transferring in fiber core coupled to the surface of the aluminum rod and the confinement losses of core modes experienced an abrupt increase. The filtering characteristics could be modified by adjusting the fiber structure parameters, such as diameters of air holes and the aluminum rod. Two applications of the photonic crystal fibers being selectively infiltrated with one aluminum rod were studied. First, a polarization filter with ultrabroad bandwidth was designed based on the cascaded resonances between fiber core modes and surface plasmon polariton modes. The bandwidth of the polarization filter was as broad as 600 nm covering wavelengths from 1.4 to 2.0 μm. Second, an intensity-type refractive index sensor was designed based on the filtering characteristics. The output power ratio and sensitivity increased as the refractive index of analyte increases and reached to 3.91 dB and 128 dB/RIU in x-polarized direction at the analyte refractive index of 1.37, respectively. [ABSTRACT FROM PUBLISHER]

A single-polarization photonic crystal fiber (PCF) based on surface plasmon resonance (SPR) is proposed. Finite element method is employed in simulating the PCF with gold-coated. The resonance wavelength can be modulated by changing the thickness of gold layer. At the resonance wavelength 1.55 μm, the loss of y-polarized mode is much larger than the loss of x-polarized mode. When the fiber length is set to 2 mm, the value of extinction ratio reaches to −118.7 dB, the y-polarized mode is suppressed and only x-polarized mode can be guided. The fiber is applicable in the production of single-polarization filter. The PCF has a simple structure and a big error tolerance, it has a good practicability. [ABSTRACT FROM AUTHOR]

A polarization filter at the two communication windows of 1.31 and 1.55 μm based on photonic crystal fiber (PCF) coated by nanoscale gold film is proposed. The effects of geometrical parameters of the PCF on the performances of polarization filter are evaluated by finite element method (FEM). Numerical simulations reveal that the polarization filter possesses ultra-short length of 400 μm and high extinction ratios of 41 and −150 dB at the communication wavelengths of 1.31 and 1.55 μm respectively. The bandwidth of extinction ratio (ER) better than 20 dB is 58 nm at the communication window of 1.31 μm. Moreover, the bandwidth of ER better than −20 dB is 164 nm at the communication window of 1.55 μm. [ABSTRACT FROM AUTHOR]

A tunable fiber polarization filter by filling different index liquids into the central hole of photonic crystal fiber (PCF) is proposed and demonstrated. The dispersion characteristics and loss spectra of the polarization filter are evaluated by finite element method (FEM). The gold wires are selectively filled into the cladding air holes of the PCF. When the phase matching condition is satisfied, the liquid-core mode couples to surface plasmon polaritons (SPP) mode intensely. The resonance wavelength varies with the change of the structural parameters and liquids. By adjusting the refractive index of the liquid, we realize the polarization filter at the wavelength of 1.31, 1.49, and 1.55 $\mu$m, respectively, under the optimized structural parameters. This is the first time to propose the narrowband polarization filter at the communication wavelength of 1.31 $\mu$m to our best knowledge based on the coupling between liquid-core mode and SPP mode, and the full width half maximum (FWHM) is only 16 nm. The loss of X-polarized mode is 44336 dB/m at $\lambda$ = 1.31 $\mu$m, and the corresponding loss of Y-polarization mode is 224 dB/m. By comparison, we find the birefringence in our structure is further better than that in conventional structure. High birefringence is helpful to separate the resonance wavelength positions of the two orthogonal polarized modes. The result also reveals that resonance loss becomes small with increasing the distance between liquid core and gold wire. [ABSTRACT FROM PUBLISHER]

The polarization filter characteristics of Au wires and liquid crystal infiltrated photonic crystal fibers are investigated by using the finite element method. The nematic liquid crystal of E7 being injected into cladding air holes is benefit to induce large birefringence under controllable electrical field. The simulation results show that the surface plasmon resonance is strongly inspired by core modes in y-polarized direction. Meanwhile, the coupling between core modes in x-polarized direction and surface plasmon polaritons modes is faint. The confinement losses can achieve 446 dB/cm in y-polarized direction and 0.8 dB/cm in x-polarized direction at wavelength of 1550 nm in one of our designed fiber. The effects of fiber structural parameters and temperature are investigated with a view of tuning and optimizing the confinement loss spectrum. Own to the large contrast of confinement losses in two orthogonal directions, the designed Au wires and liquid crystal infiltrated photonic crystal fibers promise candidate for tunable polarization filter devices. [ABSTRACT FROM AUTHOR]

With the homemade solid-core silica-based photonic crystal fiber (PCF), we observe the generation of soliton and four-wave mixing (FWM) when the femtosecond pulse is pumped at 0.822 \mu\m , belonging to the normal-dispersion regime. It is generally acknowledged that FWM is unrelated to third-order dispersion, whereas we use the fourth-order Runge–Kutta method to simulate the PCF properties by taking into account the third-order dispersion or not; the result we got is different from the conventional one. The numerical simulations are greatly consistent with the experiment results, and the FWM is dominated by negative fourth-order and negative sixth-order dispersion in the experiment. The main dynamic process is explained as the soliton, and the FWM generation can be induced by third-order dispersion. We indicate that low Raman threshold has played a very active role in this process, and we propose a conception of stimulated FWM effect in this paper. [ABSTRACT FROM PUBLISHER]

An ultrabroad bandwidth polarization filter based on D-shaped photonic crystal fibers with gold film is proposed. The design of gold film deposited on the polished plane of the D-shaped photonic crystal fibers is benefit to generate multiple resonances between surface plasmon polaritons and photons. In our designed polarization filter, the resonant intensity in y-polarization direction is much stronger than in x-polarization direction. An ultrabroad bandwidth of exceeding 1 μm with extinction ratio better than -20 dB is obtained. The performance characteristics of the filter can be improved further by optimizing the structure parameters of the D-shaped photonic crystal fibers. [ABSTRACT FROM AUTHOR]

A broadband single-polarization photonic crystal fiber polarized filter based on surface plasmon resonance is proposed based on finite element method. Numerical simulations show the confinement loss of y-PCM (y-polarized core mode) is much higher than that of x-PCM (x-polarized core mode) in the wavelength range 1.20-1.63 μm. The confinement loss of y-polarized mode is 45,240 and 10,200 dB/m at the communication wavelength 1.31 and 1.55 um, respectively, and the corresponding loss of x-polarized mode is just 90 and 80 dB/m. When the fiber length is 3 mm, the bandwidth of extinction ratio better than -20 dB is greater than 430 nm covering almost all the communication wavelength. To our best knowledge, the bandwidth is the widest. The impacts of structural parameters on the resonance characteristics are also discussed. The structure could be further optimized for better result. [ABSTRACT FROM AUTHOR]

A novel polarization splitter based on d-shaped dual-core photonic crystal fiber with gold film is proposed and analyzed by the finite element method. The designed polarization splitter involves side-polishing of photonic crystal fiber and depositing of gold film. The numerical results reveal that the separate length is 0.782 mm and the extinction ratios are -151 and -55 dB for the x- and y-polarized modes at the communication wavelength of 1,550 nm. The bandwidths of the polarization splitter are 40 and 65 nm for the x- and y-polarized modes with extinction ratios better than -20 dB and insertion losses lower than 0.3 dB. This d-shaped dual-core photonic crystal fiber is competitive for polarization splitter. [ABSTRACT FROM AUTHOR]

A polarization splitter in three-core photonic crystal fiber with rectangle lattice based on resonant tunneling effect is studied by the finite element method. The transverse-electric (TE) mode polarized light is limited to the launched port and the transverse-magnetic (TM) mode polarized light can directionally couple to the other port due to the large birefringence. A polarization splitter with a coupling length of 2.592 mm, extinction ratios ofERA= –151 dB andERC= –22 dB, insertion losses ofILTE= 0.027 dB,ILTM= 2.89E–15, and 15 dB, and a bandwidth of 29 nm at the communication wavelength of 1550 nm is obtained. The designed polarization splitter exhibits nice performance characteristics under reasonable fabrication tolerance. The characteristics of the polarization splitter are influenced by the effect of surface plasmon resonance. The golden wires infilling into the air holes reduce the coupling length to 1.695 mm. [ABSTRACT FROM AUTHOR]

A circular ultra-short A s 2 S 3 filled double-core photonic crystal fiber polarization beam splitter is proposed. The finite element method is used to study the performance of the designed photonic crystal fiber polarization beam splitter. By filling high refractive index A s 2 S 3 into the central air hole, the coupling performance of the double-core PCF is improved. By optimizing geometric parameters, the splitting length of the circular beam splitter can be as short as 72.43 μ m, and the extinction ratio can reach −151.42 dB. The high extinction ratio makes the circular polarization beam splitter have a good beam splitting function. The designed circular double-core photonic crystal fiber has the same cladding pore diameter, which is easier to prepare than other photonic crystal fibers with complex pore structure. Due to the advantages of high extinction ratio, extremely short beam splitting function and simple structure, the designed polarization beam splitter will be widely used in all-optical networks and optical device preparation. [ABSTRACT FROM AUTHOR]

A polarization-dependent supercontinuum spectrum source of light from the UV to infrared region has been generated in our photonic crystal fiber with birefringence B = 2.23×10. By tuning the polarization direction of the input pulse, it is found that the width of the supercontinuum spectrum changes dramatically with the input polarization directions. At the same time, we qualitatively explain the blue-shift peak and the red-shift peak in the experimental spectrum using phase matching conditions on dispersive waves, stoke waves and the pump wave. In addition, we also found that supercontinuum spectrum generation, to some extent, is dependent on the pump wavelength and average power of the pump. The spectrum is broadened with the increase of average power, but unchanged after average power reaches a certain value; when the pump wavelength is located in the anomalous dispersion and further away from the zero-dispersion wavelength, the spectrum of the supercontinuum is wider. [ABSTRACT FROM AUTHOR]

This paper proposes a highly sensitive surface plasmon resonance (SPR) refractive index sensor based on the photonic crystal fiber (PCF). The optical properties of the PCF are investigated by modulating the refractive index of a liquid analyte. The finite element method (FEM) is used to calculate and analyze the PCF structure. After optimization, the fiber can achieve high linearity of 0.9931 and an average refractive index sensitivity of up to 14,771.4 nm/RIU over a refractive index range from 1.47 to 1.52, with the maximum wavelength sensitivity of 18,000.5 nm/RIU. The proposed structure can be used in various sensing applications, including biological monitoring, environmental monitoring, and chemical production with the modification and analysis of the proposed structure. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The characteristics of a novel dual-core photonic crystal fiber are investigated. In the center of photonic crystal fiber, an energy transmission channel is introduced. The optimized photonic crystal fiber can be used for polarization splitter, which has a short length and low loss. [ABSTRACT FROM AUTHOR]

The novel offset core photonic crystal fiber filter is designed and analyzed, whose dispersion relations and polarization characteristics are simulated by finite element method using COMSOL Multiphysics software. The filter structure is optimized by changing diameter of air holes and the thickness of Au layer. Simulation results show that loss of y-polarized mode reaches 657 dB/cm while the loss of x-polarized mode is very low at the communication window (1.55μm). The crosstalk of filter reaches 56.2 dB at 1.55μm wavelength and the 20 dB band width of the filter is 100 nm when the propagation distance is 1μm. Not only the filter shows good performance but also the proposed photonic crystal fiber can be applied to other fields. [ABSTRACT FROM AUTHOR]