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The article is devoted to the numerical modeling of photonic crystal fibers. To this end, a nonlinear eigenvalue problem for a system of Muller boundary integral equations is constructed. To discretize it, the Galerkin method with an orthogonal trigonometric basis is used. The matrix elements of the nonlinear algebraic eigenvalue problem are calculated explicitly. As a numerical example, propagation constants and eigenwaves of a photonic crystal fiber with a liquid crystal core are found. [ABSTRACT FROM AUTHOR]

This paper presents the results of a detailed theoretical study of the bending properties of original all-glass leakage channel microstructured optical fibers (LC MOFs) over a bending radius range from 3 cm to 11 cm. These LC MOFs contain two layers of fluorine-doped silica glass elements with reduced refractive index, different diameters, and different distances between them. We determined the spatial distributions of the electric field components of different modes in addition to the usual parameters such as effective refractive indices, bending losses, and spatial intensity distributions. A detailed analysis showed that three modes for each polarization have to be considered to correctly calculate the bending losses. Two pairs of these three modes couple in two distinct bending radius ranges, specifically near 3.68 cm and near 5.95 cm, and the mode coupling in these pairs is resonant. The resulting bending losses of the LC MOF for two polarizations are very close to each other and have two maxima at bending radii of 3.68 cm and 5.95 cm. However, the nature of these maxima is not resonant; they are caused by the combined influence of all three modes, each of which has specific dependencies of losses and other parameters on the bending radius that exhibit quasi-resonant behavior near the corresponding bending radii. [ABSTRACT FROM AUTHOR]

In this paper, we design and demonstrate an all-fiber-sensitive refractive index (RI) sensor based on the Mach–Zehnder interferometer (MZI). It is constructed by splicing two no-core fibers (NCFs) and a photonic crystal fiber (PCF) between two single-mode fibers (SMFs) to obtain an SMF–NCF–PCF–NCF–SMF composite structure (SNPNS). A study of the effect of varying PCF lengths on the RI reveals that the shorter the length, the higher the sensitivity. The maximum RI sensitivity of 176.9 nm/RIU is attained within the RI range of 1.3365–1.3767 when the PCF length in the SNPNS structure is 3 cm. Meanwhile, the sensor exhibits a high stability in water, with an RSD of only 0.0019% for the interference trough over a duration of two hours. This proposed sensing structure offers the advantages of a large extinction ratio, small size, low temperature sensitivity, and simple fabrication, exhibiting a great potential in RI measurements. [ABSTRACT FROM AUTHOR]

Abstract In our study, we conducted a thorough analysis of the spectral characteristics of a D-shaped surface plasmon resonance (SPR) photonic crystal fiber (PCF) refractive index sensor, incorporating a full width at half maximum (FWHM) analysis. We explored four distinct plasmonic materials-silver (Ag), gold (Au), Ga-doped zinc oxide (GZO), and an Ag-nanowire metamaterial-to understand their impact on sensor performance. Our investigation encompassed a comprehensive theoretical modeling and analysis, aiming to unravel the intricate relationship between material composition, sensor geometry, and spectral response. By scrutinizing the sensing properties offered by each material, we laid the groundwork for designing multiplasmonic resonance sensors. Our findings provide valuable insights into how different materials can be harnessed to tailor SPR sensing platforms for diverse applications and environmental conditions, fostering the development of advanced and adaptable detection systems. This research not only advances our understanding of the fundamental principles governing SPR sensor performance but also underscores the potential for leveraging varied plasmonic materials to engineer bespoke sensing solutions optimized for specific requirements and performance metrics.

Abstract For the polarization multiplexing requirements in all-optical networks, this work presents a compact all-fiber polarization beam splitter (PBS) based on dual-core photonic crystal fiber (PCF) and an elliptical gold layer. Numerical analysis using the finite element method (FEM) demonstrates that the mode modulation effect of the central gold layer effectively reduces the dimensions of the proposed PBS. By determining reasonable structural parameters of the proposed PCF, the coupling length ratio (CLR) between X- and Y-polarized super-modes can approach 2, achieving a minimal device length of 0.122 mm. The PBS exhibits a maximum extinction ratio (ER) of − 65 dB at 1.55 μm, with an operating bandwidth spanning 100 nm (1.5–1.6 μm) and a stable insertion loss (IL) of ~ 1.5 dB at 1.55 μm. Furthermore, the manufacture feasibility and performance verification scheme are also investigated. It is widely anticipated that the designed PBS will play a crucial role in the ongoing development process of miniaturization and integration of photonic devices.

The mode coupling in a graded-index polymer photonic crystal fiber (GI PPCF) with a solid core has been investigated using the Langevin equation. Based on the computer-simulated Langevin force, the Langevin equation is numerically integrated. The numerical solutions of the Langevin equation align with those of the time-independent power flow equation (TI PFE). We showed that by solving the Langevin equation, which is a stochastic differential equation, one can successfully treat a mode coupling in GI PPCFs, which is an intrinsically stochastic process. We demonstrated that, in terms of effectiveness, the Langevin equation is preferable compared to the TI PFE. The GI PPCF achieves the equilibrium mode distribution (EMD) at a coupling length that is even shorter than the conventional GI plastic optical fiber (POF). The application of multimode GI PCFs in communications and optical fiber sensor systems will benefit from these findings. [ABSTRACT FROM AUTHOR]

Chikungunya virus (CHIKV) poses a significant public health threat due to its capacity to cause widespread and debilitating outbreaks. The virus is responsible for CHIKV fever, a disease characterized by severe joint pain, sudden onset of fever, headache, muscle pain, and rash. The virus has been reported in various regions globally, with outbreaks occurring in parts of Africa, Asia, the Americas, and the Indian subcontinent. Consequently, the scientific community expends substantial efforts in developing dependable, rapid, highly sensitive, and cost-effective techniques in order to identify the CHIKV virus. In this study, an innovative biomedical sensor using photonic crystal fiber technology enables precise detection of the CHIKV virus through uric acid, normal and infected plasma, red blood cells, and platelets in the blood. The introduced sensor identifies those kinds with extremely increased relative sensitivity and minimal losses in contrast to alternative photonic crystal fiber-based biosensors. The introduced sensor showcases a minimal confinement loss of 2.25 × 10− 13 cm− 1, a relative sensitivity of 99.37%, an effective area of 1.36 × 105 µm2, with a minimal effective material loss of 0.001966 cm–1, a numerical aperture of 0.1874, and low dispersion of 0.06. Also, the demonstrated sensor is able to function within the terahertz spectrum, covering a substantial span from 0.8 to 2.6 THz. Furthermore, an extensive comparison analysis is performed between the showcased sensor and related literature on photonic crystal fibers to verify the reliability and effectiveness of the introduced structure. [ABSTRACT FROM AUTHOR]

We report the design and theoretical study of a Ga‐Sb‐S chalcogenide glass‐based photonic crystal fiber (PCF) structure for mid‐infrared supercontinuum generation. The proposed design is engineered by adjusting the diameter of air holes in the cladding region and pitch, giving us control over the dispersion characteristics of the fiber. The optimized structure design offers the Zero Dispersion Wavelength of 5.2 μm. When pumped with 50 fs secant hyperbolic pulses of peak power 4.9 kW, for a fiber of length 8 mm at pump wavelength of 5 μm, the proposed structure design produces an ultra‐broadband supercontinuum spectrum spanning 1.5–14 μm. Proposed PCF design should be helpful in, biomedical imaging, supercontinuum sources, biosesning, and optical coherence tomography. [ABSTRACT FROM AUTHOR]

Generally, fiber with a large mode area is desired for fiber laser and beam delivery applications. But the use of these fiber types is restricted to linear optical applications due to the lower value of the nonlinear coefficient. This paper investigates a single material-based photonic crystal fiber (PCF) with improved optical characteristics, applicable for linear and nonlinear optics. The light propagation in the structure is explored by applying finite element solver-based COMSOL multiphysics software. Five nonlinear optical materials are utilized as background material to get the optimized material with high performance PCF. Using this PCF, the improved optical properties of PCF such as moderate effective mode area of 115.85 μ m 2 , chromatic dispersion, confinement loss of 10 − 6 dB/m, the nonlinear coefficient of 543W − 1 Km − 1 , splicing loss of 2.013 dB, and numerical aperture are numerically analyzed. This single-mode PCF also shows the low bending loss for the bending radius of 7 mm. The amended PCF structure is found to be suitable for high-power fiber laser, supercontinuum generation, wavelength conversion, and slow-light generation. [ABSTRACT FROM AUTHOR]

This paper presents a photonic crystal fiber (PCF) sensor that can be used to measure the temperature and magnetic field simultaneously, and to monitor the changes in them in the environment. When we designed the fiber structure, two circular channels of the same size were added to the fiber to facilitate the subsequent addition of materials. A gold film is added to the upper channel (ch1), and the channel is filled with a magnetic fluid (MF). The sensor can reflect changes in the temperature and magnetic field strength. The two channels containing MF and PDMS in the proposed fiber are called ch1 and ch2. The structure, mode and properties (temperature and magnetic field) were analyzed and discussed using the finite element method. By using the control variable method, the influence of Ta2O5 or no Ta2O5, the Ta2O5 thickness, the diameter of the special air hole, the distance from the fiber core and the distance between them in the displacement of the loss spectrum and the phase-matching condition of the coupling mode were studied. The resulting maximum temperature sensitivity is 6.3 nm/°C (SPR peak 5), and the maximum magnetic field sensitivity is 40 nm/Oe (SPR peak 4). Because the sensor can respond to temperature and magnetic field changes in the environment, it can play an important role in special environmental monitoring, industrial production and other fields. [ABSTRACT FROM AUTHOR]

This paper uses numerical investigation to present an efficient photonic crystal fiber (PCF) surface plasmon resonance (SPR) sensor. The proposed sensor is simulated and modelled by the finite element method (FEM). The plasmonic and analyte layers are utilized on the fiber's exterior to ease practical implementation. Additionally, the designed sensor contains all the circular air holes, making it simpler and easier to fabricate using currently available techniques. Silver (Ag) and tantalum pentaoxide (Ta2O5) are used as plasmonic materials for surface plasmon generations and to achieve smooth coupling. The sensor achieves the maximum wavelength sensitivity of 22860 nm/RIU and amplitude sensitivity of 1758 1/RIU. Moreover, the sensor shows a wide refractive range of chemical sensing capabilities within 1.375-1.400. Due to the broad RI detection range, the proposed sensor can detect various biological cells, biochemicals, and food additives, making this sensor applicable in medical applications and food quality control. [ABSTRACT FROM AUTHOR]

This work designed and implemented of photonic crystal fiber Fabry–Perot interferometer based on (SPR) technology for sensing the humidity of the environment. The FPI was created by directly splicing a short length of PCF (4 cm) solid core on one side with traditional multimode fiber (MMF) and depositing a nano-film of gold with a thickness of 40 nm on the end of the PCF sensor. The PCF–SPR experiment was observed for different degrees of relative humidity. The location of the resonant wavelength peaks is seen to change to longer wavelengths (redshift) as (the RH) increases due to the transmission of maximum energy from the reflected power of the light guided via the fiber to the surface plasmons. The calculated sensitivity, signal-to-noise ratio, figures of merit, and resolution are approaching; the S is 1.25 nm/%RH, SNR is 0.0066, the resolution is 0.08, and the FOM is 0.00083 for photonic crystal fiber. [ABSTRACT FROM AUTHOR]

A photonic crystal fiber (PCF) having hybrid structure cladding with an octagonal core has been introduced for use in liquid (petrochemical) sensing. Mathematical analysis has been done on the sensor performance in the 0.8–3.0 THz frequency range. Kerosene, diesel and purified petrol are pumped inside the core hole. Terahertz (THz) frequencies are used in the analysis as well as changing strut size to investigate the sensor's performance. PCF sensor exhibits a CL of 5.10 × 10–13 dB/m at 2.2 THz and a relative sensitivity of about 95.5%. The PCF also has effective area of 5.27 × 10−08 m2 along with very small EML of 0.00920 cm−1, and size of the spot is 2.563 × 10−04 μm. Several real-world terahertz usages will be conceivable thanks to the amazing accomplishments achieved with this optical waveguide. [ABSTRACT FROM AUTHOR]

The dodecagonal hollow core PCF-based edible oil sensor is put forward in this paper and quantitatively investigated over the terahertz regime. A professional tool based on the finite element method (FEM) called COMSOL Multiphysics is used to evaluate the proposed sensor's performance. The simulation findings show that the proposed sensor outperformed previous studies with high sensitivity of 102.07% and an incredibly low total loss of 4.35 × 10 - 4 cm - 1 at 3.2 THz with the optimum geometric parameters. In addition, this sensor has a high numerical aperture of 0.43 with ultra-low confinement loss of 4.92 × 10 - 15 dB/m . The huge hexagonal-shaped cladding uses to simplify its fabrication. Soon, everyday life oil detection technologies will heavily rely on its exceptional sensitivity and directing abilities. [ABSTRACT FROM AUTHOR]

In order to achieve a high-precision synchronous detection of two different refractive index (RI) analytes, a D-type surface plasmon resonance (SPR) photonic crystal fiber (PCF) RI sensor based on two channels is designed in this paper. The sensor uses a D-shaped planar region of the PCF and a large circular air hole below the core as the sensing channels. Surface plasmon resonance is induced by applying a coating of gold film on the surface. The full-vector finite-element method (FEM) is used to optimize the structural parameters of the optical fiber, and the sensing characteristics are studied, including wavelength sensitivity, RI resolution, full width at half maximum (FWHM), figure of merit (FOM), and signal-to-noise ratio (SNR). The results show that the channel 1 (Ch 1) can achieve RI detection of 1.36–1.39 in the wavelength range of 1500–2600 nm, and the channel 2 (Ch 2) can achieve RI detection of 1.46–1.57 in the wavelength range of 2100–3000 nm. The two sensing channels can detect independently or simultaneously measure two analytes with different RIs. The maximum wavelength sensitivity of the sensor can reach 30,000 nm/RIU in Channel 1 and 9900 nm/RIU in Channel 2. The RI resolutions of the two channels are 3.54 × 10−6 RIU and 10.88 × 10−6 RIU, respectively. Therefore, the sensor realizes dual-channel high- and low-RI synchronous detection in the ultra-long wavelength band from near-infrared to mid-infrared and achieves an ultra-wide RI detection range and ultra-high wavelength sensitivity. The sensor has a wide application prospect in the fields of chemical detection, biomedical sensing, and water environment monitoring. [ABSTRACT FROM AUTHOR]

A double U-shaped PCF-SPR sensor is proposed for the detection of analytes with low refractive indexes (RI). The U-shaped structure facilitates the penetration of analytes. Compared with a single formant sensor, the sensor exhibits double formant characteristics. Therefore, the analytes to be measured can be identified more accurately. This study employs the finite element method (FEM) to analyze the sensor. The findings suggest that the sensor is capable of detecting analytes with low RI ranging from 1.15 to 1.33 over an ultra-wide wavelength range of 800–6400nm. The maximum wavelength sensitivities of the first and second peaks of the sensor are 54,300nm/RIU and 60,000nm/RIU, respectively. In addition, this paper introduces double peak shift sensitivity (DPSS), the highest DPSS value is 55,700nm/RIU. Owing to these distinct characteristics, the sensor has great application prospects in the field of biosensing, especially in drug detection. [ABSTRACT FROM AUTHOR]

A surface plasmon resonance-based hollow core photonic crystal fiber (HC-SPR-PCF) is developed to detect gasoline adulteration with kerosene. The SPR-PCF sensor is fabricated via stack and draw, and atomic layer deposition (ALD). The performance of SPR-PCF sensors, such as sensitivity, loss, figure of merit (FoM), responsivity, and response time, are analysed experimentally in the wide refractive index (RI) range of 1.428–1.45. This experimental result shows that the proposed sensor with thin gold and aluminium oxide (Au + Al 2 O 3 ) plasmon active material exhibits a high amplitude sensitivity (321.59/RIU), low loss (0.0529 dB/cm), high responsivity (0.355875), and good FoM (1247.5/RIU). The presented experimental study has excellent potential in biochemical sensing applications due to its high sensitivity, low loss, linearity and fast response time. [ABSTRACT FROM AUTHOR]

An innovative photonic crystal fiber (PCF) biosensor using surface plasmon resonance (SPR) to diagnose six distinct kinds of cancers (skin cancer, cervical cancer, adrenal gland cancer, blood cancer, and breast cancer types 1 and 2) in cells is demonstrated here and incorporates with two microchannels and a bimetallic configuration. The numerical analysis utilizes the finite element method (FEM) combined with perfectly matched layers (PML). The plasmonic material employed in the biosensor is gold (Au), and a supportive material, titanium dioxide (TiO2), is combined with Au. By combining these two materials, the sensor's performance is improved. The numerical calculations indicate that breast cancer type 2 has the highest wavelength sensitivity (24,285.71 nm/RIU) and amplitude sensitivity (3959 RIU−1). The rest of the cancer cells' wavelength sensitivities are 11,000.00 nm/RIU (skin cancer), 13,333.33 nm/RIU (cervical cancer), 15,000.00 nm/RIU (blood cancer), 17,142.85 nm/RIU (adrenal gland cancer), and 21,428.57 nm/RIU (breast cancer type 1). This advanced biosensor has several uses in biological sensing and medical technology, and it has the potential to revolutionize cancer identification and medical diagnosis. [ABSTRACT FROM AUTHOR]

In response to the immediate requirements of modern high-speed and high-capacity integrated optical circuit development, this study introduces a broadband all-fiber polarization beam splitter (PBS) based on silicon dual-core photonic crystal fiber (PCF) and gold layers. Simulation results demonstrate that silicon as the substrate material is conducive to extending the operating range to the mid-infrared band of 3.0 ~ 3.6 μm. The modulation effect of the gold ring layers on the left and right sides of central elliptical hole is very impressive, and when the cladding hole diameter d1 = 1.3 μm, gold-coated hole diameter d2 = 1.8 d1 = 2.34 μm, hole-to-hole pitch Λ = 2.0 μm, gold layer thickness t = 50 nm, long axis a = 2.08 μm, and short axis b = 1.43 μm, coupling length ratio (CLR) between x- and y-polarized super-mode exactly is equal to 2. According to performance investigation by finite element method (FEM), this PBS is well suited for splitting out x-polarized light in core A, which can possess a minimum size of 0.66 mm, a maximum extinction ratio (ER) of 78 dB at 3.3 μm, a broad operating bandwidth of 450 nm, and a low insertion loss (IL) of 0.15 dB at 3.3 μm simultaneously. The proposed PBS features both high integration and high performance, which will be applicable to all-optical networks in mid-infrared fields. [ABSTRACT FROM AUTHOR]

Diabetes is a metabolic disease that seriously endangers human health, and monitoring glucose levels is one of the main diagnostic methods for its prevention and treatment. In this paper, we propose a high-performance glucose sensor based on the Sagnac interferometer (SI) utilizing photonic crystal fiber (PCF) with micro-holes. By setting two columns of micro-holes in the center of the PCF, the high birefringence effect is obtained to improve the detection sensitivity. All air holes are assumed to fill with the glucose solution, and the sensing characteristics of the PCF sensor are theoretically studied by the finite element method (FEM). The results show that the sensitivity and resolution of the PCF glucose sensor can reach 4.14 nm/(g/L) and 0.48 mg/dL within the concentration range of 0–120 g/L, respectively. In addition, the effects of the partial-filling methods and PCF structural parameters on the sensing performance are also analyzed to achieve optimal performance. The proposed glucose sensor possesses high sensitivity and simple structure, which exhibits good application prospects in the field of medical monitoring. [ABSTRACT FROM AUTHOR]

This study proposed photonic crystal fiber sensors with two distinct plasmonic layers were proposed and compared in order to identify skin cancer cells in comparison to normal blood cells. In order to attain high sensitivity for the detection of this surface plasmon resonance (SPR)-based sensor, a comparison is made between several layers of Silver-Titanium dioxide and Gold-Titanium dioxide. In addition, the presence of a TiO2 layer helps to lessen the chemical instability of silver and improves the SPR effect. For the purpose of this work, a numerical analysis of the sensor was performed using the finite element technique. It is possible to quantify the confinement loss of two sensors, as well as their sensitivity to changes in amplitude and wavelength, by modifying some influential factors such as the diameter of the airhole and the thickness of the plasmonic layer (Ag, Au). This allows for the evaluation of the effectiveness of the sensors in detecting a target analyte. For the purpose of identifying skin cancer cells, the highest amplitude sensitivity of silver as a plasmonic layer is 610 RIU-1, and the maximum spectral sensitivity is 7500 nm/RIU. The greatest spectral sensitivity of gold as a plasmonic layer for the detection of skin cancer cells is 7000 nm/RIU, while the maximum amplitude sensitivity of gold is 800 RIU-1. In-depth discussion has been held regarding the manufacturing procedure for the sensor that has been proposed. When it comes to the detection of organic and biological compounds, this biosensor that is now under investigation demonstrates promising characteristics due to its stability and good sensitivity. [ABSTRACT FROM AUTHOR]

For the polarization multiplexing requirements in all-optical networks, this work presents a compact all-fiber polarization beam splitter (PBS) based on dual-core photonic crystal fiber (PCF) and an elliptical gold layer. Numerical analysis using the finite element method (FEM) demonstrates that the mode modulation effect of the central gold layer effectively reduces the dimensions of the proposed PBS. By determining reasonable structural parameters of the proposed PCF, the coupling length ratio (CLR) between X- and Y-polarized super-modes can approach 2, achieving a minimal device length of 0.122 mm. The PBS exhibits a maximum extinction ratio (ER) of − 65 dB at 1.55 μm, with an operating bandwidth spanning 100 nm (1.5–1.6 μm) and a stable insertion loss (IL) of ~ 1.5 dB at 1.55 μm. Furthermore, the manufacture feasibility and performance verification scheme are also investigated. It is widely anticipated that the designed PBS will play a crucial role in the ongoing development process of miniaturization and integration of photonic devices. [ABSTRACT FROM AUTHOR]

This paper presents a numerical analysis of various sensing features of a hollow-core photonic crystal fiber-based milk sensor in the terahertz (THz) frequency range (e.g., 1.0 THz ≤ f ≤ 3.0 THz). The performance of this proposed sensor was evaluated by COMSOL Multiphysics, a commercial program that uses the finite element approach. The computational results indicate that the relative sensitivity is 97.984, 97.696, and 97.586% respectively, at f = 2.2 THz, for several types of cow milk, camel milk, and water; and the corresponding effective areas are 187,210, 187,870, 186,170 μm2. In addition, it has been explained that the effective material loss for water, cow, and camel milk is 0.0066172, 0.0066961, and 0.0066991 cm−1, respectively. Moreover, the proposed sensor also has low confinement losses are 1.86 × 10–13, 1.89 × 10–13, 1.891 × 10–13 dB/m a high numerical aperture (0.37), and birefringence is 4.5 × 10–04 under ideal geometry and operational circumstances compared to the previous research work. This sensor may be produced using standard manufacturing techniques, and due to its enhanced detecting capabilities, it can be a crucial part of milk sensing devices implemented in real life such as industry fields related to milk sensing by fabrication using the 3D printing method. [ABSTRACT FROM AUTHOR]

In this paper, a novel D-shaped photonic crystal fiber (PCF) refractive index (RI) sensor based on surface plasmon resonance (SPR) effect is proposed. By introducing a smiley-faced hole and Ag-TiO2 composite micro-grating, the high RI sensing performances can be realized. With finite element method, the propagation characteristics of the proposed D-shaped SPR-PCF RI sensor are numerically investigated. The simulation results show that the average wavelength sensitivity (WS) is 5400 nm/RIU, and the maximum WS can reach 15,500 nm/RIU in the RI range from 1.30 to 1.39. Besides, the proposed D-shaped SPR-PCF RI sensor can obtain the maximum resolution (R) of 4.95 × 10−5RIU and the maximum figure of merit (FOM) of 423.78 RIU−1, respectively. It is believed that the proposed SPR-PCF RI sensor has potential applications in the fields of environmental monitoring, biomedical analysis, and food safety management. [ABSTRACT FROM AUTHOR]

A novel Segmented Clad-Graded Index (SC-GI) photonic crystal fiber with a circular core composed of As38Se62 is proposed to realize the supercontinuum spectrum in the entire transparency range of As38Se62 (2–10 μm). SC-GI PCF conveys dual Zero Dispersion Wavelengths at around 2.4 μm and 6.4 μm. The devised PCF also offers a very small effective mode area of 2.46 μm2 and a very high nonlinear coefficient of 12,005 W−1 km−1 at the pump wavelength of 2.4 μm. Detailed numerical simulations reveal that a short length of SC-GI PCF (~ 28 mm) is capable of showing a broad SC spectrum ranging from 3 to 9.5 μm (− 30 dB level of power) using an input source of moderate peak power (1.8 kW) pumping at 3.4 μm. To the best of the author's knowledge, this is the first time report of SCG in Segmented Cladding Fiber design. The evaluated SC covers the transparency window of the background material and also covers the mid-IR region. This type of high broadening opens the gateway for applications like optical metrology, optical coherence tomography (OCT), food quality control, telecommunications and future applications covering the Mid-IR region.Please confirm the corresponding author is correctly identified and amend if necessary.Yes, Corresponding author is correctly mentioned. [ABSTRACT FROM AUTHOR]

In this article, a surface plasmon resonance (SPR) sensor based on photonic crystal fiber (PCF) is simulated and analyzed by finite element method (FEM). Gold and titanium oxide (TiO2) are used as plasmonic layers. The TiO2 layer is placed under the gold layer to increase the sensitivity of this sensor. The sensor's top and bottom surfaces are polished, and the plasmonic layer is placed on both these surfaces. Unlike sensors with typical external circular coating, less plasmonic material is used. Additionally, unlike internal coating sensors, there is no issue of partial air holes coating and achieving a uniform thickness of the plasmonic layer. Also using two plasmonic levels can expand the range of refractive index (RI) detection. The sensor's structure creates birefringence, allowing complete coupling between the core mode and both plasmonic layers. This results in more reliable detection ability. By optimizing the dimensions and arrangement of air holes and the sensor's structure, the ability to detect unknown analytes in the ultra-wide range of refractive index of 1.21–1.41 with the maximum wavelength sensitivity (WS) of 61,000 nm / RIU , the maximum amplitude sensitivity (AS) of 1294.29 RIU - 1 , the maximum figure of merit (FOM) of 657.14 RIU - 1 and the sensor resolution (SR) of 4.35 × 10–6 RIU have been obtained. This sensor operates in the visible to near-infrared wavelength range. During its design, feasibility in construction was taken into consideration, along with reducing the complexity and multiplicity of structural parameters. As a result, the sensor delivers excellent performance in detection parameters and is a suitable option for RI detection applications like organic chemicals and biosensing. [ABSTRACT FROM AUTHOR]

This study presents the design and analysis of a novel surface plasmon resonance sensor based on D-type photonic crystal fiber. The analyte channel in the sensor comprises an open ring with a thin gold film deposited on the channel, inducing the surface plasmon resonance effect to enhance the resonance effect and improve the spectral sensitivity of the sensor. The proposed design eliminates the need to introduce liquid into the analyte channel. Upon inserting the sensor into the vessel, the analyte automatically flows into the liquid channel. Simulations illustrate the capability of the proposed sensor to detect low refractive indices spanning from 1. 1 5 to 1. 2 6 , exhibiting a remarkable spectral sensitivity of up to 9000 nm/RIU. The surface plasmon resonance sensor presented in this study emerges as a competitive candidate for applications requiring low refractive index detection. It is all because of its promising sensing results, wide refractive index sensing range, and simple, compact fiber design. [ABSTRACT FROM AUTHOR]

In this paper, we have proposed a novel photonic crystal fiber (PCF) design having a spider-web (SW) cladding. The finite element method (FEM)-based COMSOL Multiphysics software has been used to investigate the guiding properties and performance of the fiber in the terahertz radiation regime. Detailed numerical analyses ensure that proposed fiber design possesses a low confinement loss ( ∼ 10 - 17 cm - 1 ) ) and low effective material loss (EML). The high core power fraction of 99 % and the effective mode area of 1.06 × 10 - 5 m 2 make this fiber an exception. V-parameter confirms the single-mode behavior of fiber over 0.1–3.0-THz frequency range. Thus, we can say that the proposed fiber can be useful in various applications of terahertz propagation such as broadband transmission, biosensors, and chemical sensors. [ABSTRACT FROM AUTHOR]

In this work, a single mode fiber (SMF) is spliced with a photonic crystal fiber (ESM-12) from both sides and tapered down to (92.1 µm) to create a surface plasmon resonance (SPR) based on Mach–Zehnder interferometer for the purpose of calculating the refractive indices of Carbonated liquids with different expiration dates. The (SMF-PCF-SMF) sensor is coated with gold film (Au) of 40 nm thickness on the stripped part of the spliced PCF to optimize the sensing performance of the fiber. The sensor has a sensitivity of (7.17) (µm/RIU), figure of merit is (19.14), signal-to-noise ratio of (0.536), and resolution of (1.3 × 10–4) (RIU). [ABSTRACT FROM AUTHOR]

In this article, a solid-core photonic crystal fiber was developed to examine different concentrations and refractive indices of dissolved glucose in water and blood samples using surface plasmon resonance. A photonic crystal fiber with coated sensor model based on (gold and silver) nanolayer was proposed. The experimental results exhibit a sensitivity of 1943.43 nm/RIU and 1892.18 nm/RIU for samples with glucose concentrations in water ranging from 80 mg/dl to 600 mg/dl when PCF is coated with gold and silver nanofilm, respectively. It also exhibits wavelength sensitivity of 1114.164 nm/RIU and 1012.364 nm/RIU for glucose concentrations in blood serum at range from 89 mg/dl to 611 mg/dl using PCF coated with identical 50 nm thick gold and silver nanofilms, respectively. It is found that the maximum resolution of the proposed PCF was 3.3 × 10–5. [ABSTRACT FROM AUTHOR]

Now a day's breast cancer is a concern in modern science and medicine, consequently establishing an effective and precise breast cancer cell detection approach becomes extremely important. Photonic crystal fiber-based sensor makes this approach smoother and more innovative. A unique THz sensor based on hollow core photonic crystal fiber facilitating chemical analytes detection within terahertz frequency range has been reported in the present work. Efficiency of the presented sensor has been investigated numerically applying simulation technology based on the finite element technique. A photonic crystal fiber biosensor is designed to detect cancerous cells, all the proposed combinations have been implemented by using finite element approach, and the performance of the proposed model has been evaluated by MATLAB software. The reported sensor could be operated in the frequency range 1.0–2.0 THz. Simulation results are found to be good enough, with highly birefringence (0.0020), lower confinement loss (17.33 × 10–9 dB/cm), lower effective area (3.04 × 10–8 µm2), a higher relative sensitivity (65.53%) along x-axis, relative sensitivity (53.63%) along y-axis, effective refractive index (1.376), nonlinear coefficient (6.38 × 1016) and dispersion (0.1588 ± 0.0121). Furthermore, the proposed sensor's manufacturing capabilities remain assured by its ease of implementation. [ABSTRACT FROM AUTHOR]

In this paper, a highly sensitive surface plasmon resonance-based photonic crystal fiber sensor for low refractive index (RI) sensing and detection is proposed. To excite the surface plasmon polariton (SPP) mode, Au and TiO2 were coated on the top and bottom of the sensor in the shape of notched rings. The utilization of TiO2 has the potential to augment the interplay between the core and surface SPP modes, leading to an enhancement of the sensitivity of the sensor. The finite element method was applied for evaluating the sensor's performance. The attainment of optimal wavelength sensitivity of 21,500 nm/RIU and matching resolution of 4.65 × 10–6 RIU was achieved through the refinement of structural parameters within the low RI detection range of 1.18–1.28. The findings of the study hold promise for potential applications in the fields of medical diagnostics and identification of low RI environments. [ABSTRACT FROM AUTHOR]

This paper presents the design of a high-efficiency spot size converter (SSC) for photonic crystal fiber (PCF) to silicon-based waveguides, utilizing composite optical waveguide structures. The SSC is composed of a series of waveguide cores, with one core progressively widening to enable all cores to collectively serve as a composite input port, while the broader core functions as the output port. Simulation results reveal that the proposed design efficiently facilitates mode and energy transfer between the waveguide and the PCF, achieving a coupling efficiency of up to 93.99% over a length of 66 μm. Additionally, the SSC exhibits polarization insensitivity, with the high circularity of the output beam enhancing vertical alignment tolerance, and maintaining excellent performance over a wide wavelength range. In sum, this SSC demonstrates excellent coupling efficiency and holds significant promise for applications in optical communication systems and optical integrated circuit systems.

This study introduces an innovative photonic crystal fiber (PCF) surface plasmon resonance (SPR) biosensor, notable for its sophisticated design and exceptional performance, utilizing gold as the plasmonic material. The sensor offers an expanded detection range and outstanding sensitivity, operating within a refractive index range of 1.27 to 1.43. It achieves a remarkable wavelength sensitivity of 157,000 nm/RIU with a resolution of 6.37 × 10⁻⁷ RIU and an amplitude sensitivity of 1263 RIU⁻¹ with a resolution of 7.92 × 10⁻⁵ RIU. Additionally, it boasts a figure of merit (FOM) of 1648, underscoring its superior capability in detecting biomolecular interactions. The suggested design is numerically analysed using the finite element method (FEM) of a gold-coated PCF-based SPR sensor designed for detecting changes in the refractive index (RI) within the range of 1.27 to 1.43. This range is related to various biological and chemical samples, including proteins, DNA, and biochemical analytes typically used in biomedical diagnostics and environmental monitoring. The integration of gold plasmonic elements enhances the sensor's sensitivity and stability while extending its detection capabilities across a broader range, allowing for versatile applications in biomedicine, environmental monitoring, and beyond. This research significantly advances optical biosensing technologies by offering a robust platform for high-precision detection across diverse domains. The sensor's advanced design and performance make it an invaluable tool for applications requiring accurate and reliable detection, driving innovations in areas such as biomedical diagnostics, environmental monitoring, food safety, and pharmaceutical quality control.

This research focuses on developing an innovative optical sensor utilizing photonic crystal fiber with a unique cladding structure. The photonic crystal fiber’s cladding consists of four layers of circular air holes, with two of them filled with hemoglobin. This arrangement renders the photonic crystal fiber sensitive to changes in hemoglobin concentration, primarily investigating its impact on chromatic dispersion – the wavelength-dependent refractive index variation. The study analyzes two specific wavelengths, 1.2 µm and 1.4 µm, finding high sensitivity at 1.2 µm, calculated to be 0.232 ps/(nm·km)/(g/L). The potential application lies in malaria diagnosis through non-invasive blood sample analysis. We selected the refractive index of an infected red blood cell at the ring stage, setting it at n = 1.395. Our proposed sensor demonstrates outstanding performance in diagnosing malaria at an HGB concentration of 38 g/L at 1.2 µm and at an HGB concentration of 40 g/L at 1.4 µm. By monitoring hemoglobin concentration changes, this photonic crystal fiber-based sensor offers a promising method for early and accurate malaria detection, thus potentially improving global healthcare.

Abstract Using the flexibility and diversity of material and structure designs possible with 3D printing fiber technology, an all‐solid photonic crystal fiber (PCF) is fabricated using borate (B2O3) doping. The geometry, material, and optical properties of this 3D printed PCF are characterized and analyzed using optical microscopy, scanning electron microscopy (SEM), fiber index profilometry, and Fourier transform infrared (FTIR) microscopy. Analysis demonstrates that B2O3 doped in fabricated PCF has experienced evaporation leading to mass loss during drawing. In addition, there is no observable difference between the structure of substrate silica (SiO2) and the SiO2 nanoparticles. However, microdomain differences may explain enhanced reflectance. Furthermore, a Mach–Zehnder interferometer (MZI) sensor is constructed with this 3D printed solid PCF and applied to temperature, refractive index, tensile force, and bending sensing. The specially designed 3D printed PCF has maximum temperature sensitivity up to Δλ/ΔT ≈0.075 nm °C−1. When immersed in 76.34 wt.% glycerol‐water solution, the sensitivity can be further improved. These results demonstrate that 3D printing fiber technology enables the custom fabrication of highly sensitive optical fiber sensors, increasing opportunities for the development of diverse and flexible sensors and devices for future internet‐of‐things (IoT) applications.

Abstract Designing Photonic Crystal Fibers incorporating the Surface Plasmon Resonance Phenomenon (PCF-SPR) has led to numerous interesting applications. This investigation presents an exceptionally responsive surface plasmon resonance sensor, seamlessly integrated into a dual-core photonic crystal fiber, specifically designed for low refractive index (RI) detection. The integration of a plasmonic material, namely silver (Ag), externally deposited on the fiber structure, facilitates real-time monitoring of variations in the refractive index of the surrounding medium. To ensure long-term functionality and prevent oxidation, a thin layer of titanium dioxide (TiO2) covers the silver coating. To optimize the sensor, five key design parameters, including pitch, air hole diameter, and silver thickness, are fine-tuned using the Taguchi L8(25) orthogonal array. The optimal results obtained present spectral and amplitude sensitivities that reach remarkable values of 10,000 nm/RIU and 235,882 RIU-1, respectively. In addition, Artificial Neural Network (ANN) optimization techniques, specifically Multi-Layer Perceptron (MLP) and Particle Swarm Optimization (PSO), are used to predict a critical optical property of the sensor confinement loss (αloss). These predictions are derived from the same input structure parameters that are present in the full L32(25) design experiment. A genetic algorithm (GA) is then applied for optimization with the goal of maximizing the confinement loss. Our results highlight the effectiveness of training PSO artificial neural networks and demonstrate their ability to quickly and accurately predict results for unknown geometric dimensions, demonstrating their significant potential in this innovative context. The proposed sensor design can be used for various applications including pharmaceutical inspection and detection of low refractive index analytes.