Search

We demonstrate numerically and experimentally the generation of the supercontinuum (SC) in water-filled-cladding photonic crystal fiber (PCF). The fiber-based on fused silica glass with regular hexagonal lattice consists of seven rings of air holes in the cladding region, which are all infiltrated with water. As result, the flat spectrum with bandwidths of 102.5 nm around the central pumping wavelength was achieved with input energy of 9.0 nJ and pulse duration of 400 fs at 1030 nm central wavelength, where the SC is mainly generated from the self-phase modulation (SPM). In addition, the chromatic dispersion of the investigated fiber was measured over a wide wavelength range from 0.6 to 1.75 μm using the Mach–Zehnder interferometer configuration and then verified against simulated results. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Spurred by the continuous development of orbital angular momentum (OAM) optical fiber communication technology, many photonic crystal fibers (PCFs) with excellent properties have been proposed. However, design and optimization of the performance of PCFs are usually complex. In this paper, a new optimization method is described and demonstrated on a LaSF09 high refractive index ring with a certain thickness inlaid in the central pore. The effective index difference, dispersion, effective mode area, nonlinear coefficient, numerical aperture (NA), OAM purity, walk-off length, and confinement loss at 1.55 μm are analyzed. A conventional photonic crystal fiber (PCF) that can transmit OAM modes is used to verify the method and our results reveal the validity and large potential of the method pertaining to the design and optimization of PCFs. [ABSTRACT FROM AUTHOR]

The present study proposes a photonic crystal fiber sensor based on a plasmon resonance. A thin gold metal layer was used as a plasmonic‐active material to produce the surface plasmons to detect changes in the refractive index (RI) around it. The performance of the proposed sensor is evaluated by the finite‐element method for various refractive indices. The sensitivity of this sensor ranges from 3740 to 51227 nm/RIU for the RI range of 1.36–1.42 in the wavelength range of 700–1900 nm. Within this range, we observed the highest resolution, the best FOM, and amplitude sensitivity with values of 1.95 × 10−6 RIU, 883.224 RIU−1, and 2328.59 RIU−1, respectively. This sensor has a simple structure and a better performance as compared with available sensors. The present study opens a new window to studies in the fields of biological materials, chemical materials, and the environment. [ABSTRACT FROM AUTHOR]

In order to realize temperature and refractive index (RI) detection of the analyte in the same space–time, a dual parameter detection photonic crystal fiber (PCF) optical sensor is proposed in this paper. Meanwhile, it can effectively avoid the interference of analyte temperature with RI detection. Furthermore, a dual polished D-type structure is designed to provide mutually independent detection channels for temperature and RI, respectively. In addition, silver is used as the metal layer material, and polydimethylsiloxane (PDMS) and titanium dioxide (TiO2) are used as the temperature-sensitive materials and RI-sensitive materials, respectively. This structure design enables the two detection results to be output in parallel without interfering with each other. The proposed optical fiber sensor has a wide detection range and good detection performance. The temperature detection range can be as wide as −60 to 100°C, and the RI detection range is 1.30–1.40. The best temperature resolution can be 1.42 × 10−2 RIU, and the temperature wavelength sensitivity is 0.7 nm/°C. While the RI wavelength sensitivity is up to 1.25 × 104 nm/RIU, and the wavelength resolution is 8 × 10−6 RIU. The detailed fabrication process of the sensor is given in this paper, as well as the practical application scenarios. Therefore, the optical fiber sensor proposed in this paper has research significance for the development of dual parameter detection optical fiber sensors. [ABSTRACT FROM AUTHOR]

We report a large mode area photonic crystal fiber with a flat-top mode field. The optical fiber has a multi-layer square structure with air holes and doped layer. A flat and top-hat-like mode intensity profile is provided through the reasonable design of the doped layer. The modal characteristics including effective mode area, dispersion, bending loss, confinement loss and field profile are investigated. The proposed fiber with a top-hat mode generation has potential applications in laser drilling, laser cleaning, imaging, spectroscopy, and so on. [ABSTRACT FROM AUTHOR]

In this paper, a photonic crystal fiber sensor for surface plasmon resonance (SPR) is proposed and verified by wavelength interrogation. The structure design of the proposed PCF model is simple, and the size of the outer air hole has little effect on the sensor performance. Compared with the previously proposed sensor, the fabrication process of the sensor is very easy. At the same time, the surface plasmon resonance effect formed by the silver film on the polished surface provides a platform for the detection of liquid analytes. The numerical simulation results show that the trapezoidal photonic crystal fiber refractive index sensor based on silver-silicon cladding has an air hole d1 = 1.2 μm, an air hole d2 = 1.3 μm, an air hole spacing v = 1.5 μm, a metal silver film thickness t_Ag = 30 nm, the best sensing performance is achieved when the silicon oxide protective layer t_SiO2 = 20 nm. Its wavelength sensitivity is 24000 nm/RIU, the analyte refractive index detection range is 1.31–1.39, the resolution is 1.1102 × 10–6, and the amplitude sensitivity is − 4314.65RIU−1. Our proposed sensor uses SIO2 layer as a protective layer, which can not only prevent the plasma metal silver film from being oxidized, but also increase the sensitivity of the sensor. Therefore, the sensor designed in this study is very suitable for organic chemical detection and medical diagnosis. [ABSTRACT FROM AUTHOR]

This paper reveals special design features of the proposed highly nonlinear circular-lattice-silicon-core and silica-doped-with-fluorine (1%) cladding-composite photonic crystal fiber (PCF) in the Mid-infrared region of the spectrum. A region of small negative group velocity dispersion (GVD), managed higher order dispersions (HODs), and unique nonlinearity of silicon have been used to demonstrate a supercontinuum broadening from 1500 nm to 4700 nm with consumption of low input power of 400 W over short fiber distances. It will be also shown that the fiber's high-level engineered structure finally results in a simple manufacturing process compared with other designed nano-sized silicon PCFs. The designed fiber could have massive potential in gas sensing, soliton effect pulse compression, spectroscopy, material processing, etc. [ABSTRACT FROM AUTHOR]

A high-sensitivity refractive index (RI) sensor is proposed and designed, which is an in-line Mach–Zehnder interferometer (IMZI) with a photonic crystal fiber (PCF) and multilevel micro spindle structures fabricated by the arc-discharging and tapering method. To improve the sensitivity, a tapered multimode fiber (MMF) is inserted into the PCF. The performance of RI and temperature detection has been analyzed and discussed. The maximum RI sensitivity of −2958.875 nm/RIU is achieved by detecting the NaCl solution. In addition, the maximum temperature sensitivity is 6.4 pm/ o C in the range of 25 o C –65 o C , and the maximum measurement error changes caused by temperature is −0.0170‰/ o C. It shows that the sensor is very sensitive to RI yet insensitive to temperature. • An in-line Mach-Zehnder interferometer is proposed. It uses multilevel micro spindle structures, photonic crystal fibers and tapered multimode fiber structure to improve sensitivity and extinction ratio. • The sensor's refractive index sensitivity reaches to −2958.875 nm/RIU in the range of 1.33–1.334. The extremely high sensitivity for refractive index is able to detect the subtle change of liquid's refractive index. • In the range of 25 °C–65 °C, the maximum temperature sensitivity is 6.4 pm/°C. It shows that the sensor is insensitive to temperature which can avoid the crosstalk between the detection of refractive index and temperature. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) sensing technology has been widely used in biometrics, but the weak detection capability and low sensitivity limit the development of SPR biosensors. In this work, we propose to employ the transition metal disulfide (TMD) material MoS 2 to induce the SPR effect into the near-infrared band. The aim of this work is to develop a near-infrared sensor capable of quantitatively detecting the concentration of cDNA, which is able to solve the problems of low sensitivity, parameter crosstalk and so on. The results show that the sensitivity of the SPR sensor at infrared wavelengths is 1.69 times higher than that of visible, and the infrared wave is more suitable as an excitation source for the SPR effect because it has a stronger evanescent field. In addition, we have prepared a DNA hybridization sensor that can work in the near-infrared band to detect complementary DNA (cDNA) concentration. Moreover, a combined cascade and parallel strategy realized the temperature and PH detection. The sensor uses the photonic crystal fiber as the platform, silver film as an excitation layer, and MoS 2 as a modulation layer. The optimal parameters of the sensor were determined during the experiment, and the three-parameter detection was successfully realized. The experimental results show that the three sensing channels can work independently, and the DNA hybridization probe can achieve selective detection of cDNA with a sensitivity as high as 0.22 nm/(nmol/L). The proposed three-channel DNA hybridization sensor has high sensitivity and accuracy. The innovation of this work is to demonstrate that infrared waves are more suitable to be used as the excitation source of SPR sensors and that the proposed three-channel sensor has a promising future in early diagnosis and biosensing. [Display omitted] • This work demonstrates that the SPR in the infrared band is more suitable for the field of biosensing. • This work presents an infrared SPR biosensor for detecting DNA concentration. • This work presents a three-channel sensor that can simultaneously detect temperature, PH and DNA concentration. • This work demonstrates the modulation effect of MoS 2 film on SPR. [ABSTRACT FROM AUTHOR]

—In this work photonic crystal fibers of different cross-sectional patterns are studied. Dirac points of these various lattices are explored, propagation diagrams showing positions of the Dirac spectrums are obtained, and their application in fiber guiding is discussed. A quasi-3D FDTD simulation method, which is simpler and more efficient than a commercial 3D FDTD simulation software, is developed for photonic crystal fiber. This method is then applied to the new photonic crystal fiber proposed in [Fiber guiding at the Dirac frequency beyond photonic bandgaps, Light Sci. & App. 4 (2015) e304.]. Dirac-point guidance, which is based on Dirac localization of photons, is verified for these fibers. • Dirac point guiding exists in lattices possess triangular and inversion symmetries. • Multiple vector Dirac modes form far away from the light line. • Quasi-3D FDTD is much more efficiency than 3D FDTD in computer memory and time. • Dirac mode enables remote coupling, results in new coupling and sensing features. [ABSTRACT FROM AUTHOR]

In this paper, a high-sensitivity biosensor for refractive index (RI) detection based on surface plasmon resonance (SPR) is proposed and analyzed. Based on the new D-shaped photonic crystal fiber (PCF). In the design, we chose gold on the polished part as the plasmonic material to improve the SPR effect. In addition, the numerical results were analyzed using the finite element method (FEM) for sensing applications. Accordingly, we measure RI at different wavelengths. The simulation results showed a high sensitivity of 12,300 nm/RIU in the RI range ranging from 1.27 to 1.41 and a maximum amplitude sensitivity AS of 1623.6 RIU−1, with a sensing RI resolution of 8.13 × 10−6 RIU and a maximum figure of merit (FOM) of 560 RIU−1. Due to the excellent parameters of the proposed sensor and the possibility of measuring larger RI ranges of the analyte, it is believed to be very useful in biomedicine and environmental sciences. [ABSTRACT FROM AUTHOR]

Optical fiber sensing has a wide range of applications in various fields. It requires strong sensitivity and synergistic effects of sensors. Two-dimensional materials have been extensively explored, due to their excellent properties and great applications in electronics, optoelectronics, spintronics, and other fields. In this paper, we combined optical fiber sensing with two-dimensional materials and have presented an ultra-high sensitivity two-polarized D-type photonic crystal fiber (PCF) sensor on the basis of molybdenum dioxide (MoO2) nanofilm. Numerical simulations show that the sensor is able to detect the refractive index (RI) of the analyzer from 1.393 to 1.416. The average wavelength sensitivity of the sensor is 21,668.81 nm/RIU in the x-polarized direction and 23,401.80 nm/RIU in the y-polarized direction. It has been shown that MoO2 has the great potential for optical fiber sensing as a plasmonic sensing material. [ABSTRACT FROM AUTHOR]

Photonic crystal fiber (PCF) is a crucial component of optical fiber. Today, PCF has sparked widespread interest because of its potential in sensor systems, photonic devices, and communication. However, the features of technologies are updating day by day, and to keep up with the latest features, optical fiber sensors are a key issue for the Internet of Things (IoT) technologies. The primary goal of the offered project is to design an optical sensor for IoT-compatible devices with maximum sensitivity and minimum loss. Therefore, this project presents a unique circular-shaped PCF sensor based on surface plasmon resonance (SPR) for evaluating analyte refractive index (RI). With the utilization of the finite element approach, the sensing capabilities of the proposed structure have been examined via numerical simulations incorporating an iterative optimization. However, in this configuration, several capillaries are collected and conducted to yield a circular-shaped silica structure, and the flattened layer is then coated with a gold (Au) material. The gold material obtains the SPR pulse in the PCF’s broadcast spectrum. In this structure, the operating wavelength range of 0.94–0.62 μm yields efficient results. All the parameters are numerically simulated for the analyte, with RI = 1.34–1.37. After the simulation and formal analysis, the offered sensor gives the highest wavelength sensitivity response of 18,403.59 nm/RIU and a minimum loss peak of 193.87 dB/cm. We believe the structural design can also be an appropriate candidate for biological and organic detection, as well as other IoT-based applications. [ABSTRACT FROM AUTHOR]

• The DRH-PCF is optimised in the band 1.26µm to 1.66µm and supports 200 Stable optical modes at 1.5µm. • DRH-PCF features high mode purity > 95% and flat dispersion ~3 ps/mm/km. • Low confinement loss <10−5dB/m and fiber bend (R B) tolerance (R B =1cm to 80cm). • Deep Learning model to train DRH-PCF structure. • Model prediction of n eff , a eff and estimation within <5% of numerical data. Multimode capability in photonic crystal fiber (PCF) is an important feature in fiber development. This study presents an innovative Dual Ring Hollow core PCF (DRH-PCF), designed to support a large number of multimode operations with minimal loss and flat dispersion optimized in the wavelength range of 1.26 µm to 1.66 µm. The DRH-PCF structure comprises a high-purity silica matrix, featuring a unique configuration that includes a hollow core and high indexed Lithium niobate (LiNbO 3)-Arsenic trisulfide (As 2 S 3) dual rings of thickness 0.6 µm. This arrangement is complemented by a pattern of strategically placed air holes encircling the fiber. Our PCF is engineered to support an impressive 200 and more orbital angular momentum modes, with low confinement loss (∼10−5 dB/m) and near-flat dispersion (∼3 ps/mm/km) and very large power fraction (∼0.99), while maintaining high mode purity of >95 %. Furthermore, the fiber exhibits a near-flat dispersion profile over a wide spectral range, with a measured dispersion of ∼6 ps/(nm·km) around the operational wavelength. Stability due to fiber bend is also investigated for extreme bend tolerance (Bend radii R B =1cm to 80 cm). Deep Learning prediction is used to train and predict the performance of the fiber and obtained remarkably close results (within 5 %). This combination of features makes our PCF an excellent candidate for diverse applications in high-capacity optical communication systems, sensing technologies, and nonlinear optics. [ABSTRACT FROM AUTHOR]

This work presents a photonic crystal fiber (PCF)–based surface plasmon resonance (SPR) biosensor with dual cores and bilateral-surface detection capability to enhance the early identification of cancerous cells. The biosensor processes cell samples including both malignant cancerous cells and healthy normal cells through varying refractive indices. The optimized design of the sensor achieves enhanced wavelength and amplitude sensitivities and identification accuracy in terms of resolution. The bilateral-surface precision PCF SPR biosensor allows for continuous tracking of dynamic biomolecular interactions with the plasmonic region by detecting changes in resonance conditions. The suggested biosensor is evaluated numerically using the finite element method (FEM)–based COMSOL tool. Its performance is assessed for several malignant cells such as MCF7, MDAMB231, PC12, HeLa, Jurkat, and Basal over a refractive index range of 1.360 to 1.401, and they were found to have wavelength sensitivities of 5714.28, 5714.28, 4285.72, 4285.71, 3333.33, and 3000 nm/RIU, respectively. The maximum wavelength sensitivity of 5714.28 nm/RIU is observed for the MCF7 and MDAMB231 cells, and the maximum amplitude sensitivity of 899.248 RIU-1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{-1}$$\end{document} is achieved for the MCF7 cell. The greatest sensor resolution of 3.33 ×\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\times $$\end{document} 10-5\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{-5}$$\end{document} RIU is achieved for the Basal cell. Therefore, the proposed PCF SPR sensor with its simple geometry and overall high-performance characteristics is a promising candidate for the early detection of six different cancer cells. [ABSTRACT FROM AUTHOR]

This paper describes an octagonal photonic crystal fiber (OPCF) magnetic field sensor based on the surface plasmon resonance effect. The magnetic fluid is filled into the first layer of air holes of the OPCF, and the Au is coated into the air hole located in the y-direction. The external magnetic field intensity can be determined by observing the change in the confinement loss spectra caused by the effect of the external magnetic field on the refractive index of the magnetic fluid. A finite element method is used to simulate the effects of structural parameters such as air hole diameter, stomatal spacing, and gold coating thickness on the performance of the fiber optic magnetic field sensor. The sensitivity of the proposed optical fiber magnetic field sensor is 757.1 pm/Oe, a FOM value of 2.16 Oe−1, and an AS value of 1.43 × 10−3 Oe−1, and the detection range is 50–200 Oe. The OPCF magnetic field sensor enables the development of lightweight and high-precision electromagnetic detection equipment due to the fact that OPCF magnetic field sensors do not require excessive modification of PCF, have less damage, are simple in structure, and have low production costs. It will improve the efficiency and quality of data collection in electromagnetic geological exploration and accelerate the transformation and upgradation of intelligent and green geological exploration. [ABSTRACT FROM AUTHOR]

A novel PCF-SPR sensor with hybrid sensing capability is presented in this study for detecting both coronavirus and alcohol concentration simultaneously. The sensor utilizes both external and internal sensing approaches to enable simultaneous multi-analyte detection. A thin gold film applied uniformly to the entire external surface as well as the external section of the internal circle that contains the analyte facilitates the surface plasmon resonance (SPR) phenomenon. This hybrid sensor demonstrates excellent performance across the RI range of 1.29 to 1.42 (external, 1.29–1.37; internal, 1.34–1.42). The sensor’s simulation results and performance are analyzed using the finite element method (FEM)–based COMSOL Multiphysics 5.3a. The performance parameters, including wavelength sensitivity (WS), amplitude sensitivity (AS), figure of merit (FOM), and sensor resolution (SR), are assessed for both external and internal sensing modes. The maximum WS and AS are observed to be 13,000 nm/RIU (external) and 5000 nm/RIU (internal), and -\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$-$$\end{document}1216.45 RIU-1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{-1}$$\end{document} (external) and -\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$-$$\end{document}85.8465 RIU-1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{-1}$$\end{document} (internal), respectively. The minimum SR is found to be 7.69×10-6\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$10^{-6}$$\end{document} RIU (external) and 2.00×10-5\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$10^{-5}$$\end{document} RIU (internal), while the highest FOM is noted as 650 RIU-1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{-1}$$\end{document} (external) and 66.667 RIU-1\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$^{-1}$$\end{document} (internal). The hybrid sensor is capable of detecting coronavirus samples at concentrations ranging from 0 to 62.5 nM and determining COVID-positive or negative status using a threshold of 1.953125 nM. It also detects alcohol concentrations in water mixtures ranging from 15 to 70%. With its compact design and high sensitivity, this sensor shows promise for biological analyte sensing. [ABSTRACT FROM AUTHOR]

In this proposed work, a novel graded index photonic crystal fiber (GI-PCF) with gold-TiO2 layered coating is presented as a surface plasmon resonance (SPR)-based refractive index sensor for a wide range of refractive indices. Present fiber is characterized by two types of air holes: one having gradually increasing radius and other having constant radius. The performance of the proposed sensor is tested on wavelength sensitivity (WS), amplitude sensitivity (AS), sensor resolution, and figure of merit (FOM). Detailed modal analysis of the designed SPR sensor is analyzed by the finite element method. Structural design optimization has been analyzed with respect to various different structural parameters, such as the radius of different air holes, the inherent grading of holes, and the thickness of gold and TiO2 layers. Our detailed analysis summarized the effectiveness of graded design over conventional design. The calculation result shows a high WS of 22,600 nm/RIU. Apart from high WS, an enhanced AS of -1410 RIU−1 is also observed, which is a key highlight of our PCF sensor. Further, the sensor’s resolution is also obtained having a magnitude of 4.43 × 10−6 RIU and FOM is 403.57 RIU−1. Thus, the GI-PCF sensor proves its excellent ability to measure both wavelength and amplitude sensitivity with excellent FOM for a wide range of refractive indices. Such a sensor can find its application in various sensing areas, i.e., biomedical, chemical, and industrial field. Apart from promising numerical values, the PCF structure is also possible to fabricate using currently existing fabrication techniques. [ABSTRACT FROM AUTHOR]

Large core fibers typically offer high coupling efficiency with laser sources and standard single-mode fibers in supercontinuum generation systems. However, their large cores result in large effective mode areas, leading to low nonlinearity for spectral broadening. In this paper, we report the development of a large core fiber that exhibits high nonlinearity for broad-spanning supercontinuum (SC) generation. The fiber is made of transparent glass (lead-bismuth-gallate) having high nonlinearity. The nonlinear coefficient of the fiber is 36.5 W−1 km−1 at 1560 nm, which is three times higher than that of commercial nonlinear silica fibers. The linear properties of the fiber are numerically and experimentally verified, while the nonlinear propagation is thoroughly characterized numerically, taking into account the influence of relative intensity noise (RIN) and both X-/Y- polarization components. Numerical results demonstrate that the fiber allows the high-coherence normal-dispersion SC generation with a spectral bandwidth of 850 nm (from 1300 nm to 2150 nm) when being pumped by 100 fs laser pulses at 1560 nm with a peak power of 30 kW. Anomalous-dispersion SC generation with an octave spectral bandwidth (1150 nm–2450 nm) is obtained when using 1950 nm fs pulses with a pulse duration of 100 fs and a peak power of 20 kW. In addition, the coherence degradation due to the interaction between polarization components of the fundamental mode is numerically investigated for several pulse durations (100 fs – 200 fs). The results indicate that using short laser pulses (100 fs) enables wider bandwidth SC generation with high coherence in both normal and anomalous dispersion regimes. With a large core diameter, high nonlinearity, and high transparency, the investigated fiber is well-suited to develop a compact all-fiber supercontinuum source with broad spectral bandwidth and high output power. Such a system benefits numerous applications, including multi-photon microscopy and sub-ppm detection of nerve agent simulants. [ABSTRACT FROM AUTHOR]

An intensity-demodulated fiber-optic magnetometer is proposed and experimentally investigated, which is fabricated via fusion splicing a segment of photonic crystal fiber (PCF) between single-mode fibers (SMFs), with the cladding air holes of PCF filled with magnetic fluid. Using the magneto-optical properties of the magnetic fluid, the transmission spectrum is changed with an external magnetic field. Based on the intensity variations in the transmission spectrum, the magnetic field is detected, and a sensitivity of 0.238 dB/mT is obtained at 1550.03 nm with the length of PCF 5.5 cm. By converting light signals into electrical signals, a sensitivity of 0.003 V/mT is achieved. The fiber-optic magnetometer possesses the advantages of simple fabrication, compact/robust structure, and low cost.

Photonic crystal fibers (PCFs) have emerged as promising candidates for enabling high-performance 5G communication systems, attributed to their low loss and wide bandwidth characteristics. In this research, we leverage the capabilities of COMSOL Multiphysics v5.6 software to meticulously design a novel photonic crystal fiber (PCF) design based on Topas, featuring a rectangular air gap core with integrated slots, surrounded by a cladding composed of circular and octagon air holes. The circular air holes are arranged in square and octagon lattice structures, while the octagon air holes form a rhombic lattice. The proposed structure exhibits a high birefringence of 0.05 and low effective material loss (EML) of 0.059 cm−1 and 0.057 cm−1 at 2 THz for x and y polarization mode, respectively. Moreover, the proposed waveguide also has a low confinement loss of 10−10 and 10−11 cm−1 for x and y polarization mode. Thus, the proposed PCF structure exhibits significant potential for facilitating 5G requirements.

In this work, a modified square photonic crystal fiber (MS-PCF) architecture is exposed with ultra-high negative dispersion for communication window. The validation of the model is successfully performed by applying an efficient full-vector finite element method (FV-FEM) with anisotropic perfectly matched layers (PMLs) for precise simulation of PCFs. Additionally, waveguide dispersion engineering is accomplished by tuning the structural parameters of the MS-PCF. From the numerical investigation, negative dispersion behavior permits remarkable suppression rather than positive dispersion. It offers the high negative dispersion of −2357.54 ps/nm/km and Kerr nonlinearity (γ) of 74.68 W−1 km−1 simultaneously at the operating wavelength, λ = 1550 nm. Nevertheless, the designed fiber ensures the mono mode operation in the entire band of interest from λ = 1340 nm to λ = 1580 nm. MS-PCF with these outstanding optical performances has distinguished potency to be practiced as a dispersion compensating fiber in optical communication systems.

The control of light in photonic crystal fiber (PCF) is a special characteristic that is obtained due to the relations between material and light. In this paper, a surface plasmon resonance (SPR) based PCF sensor is introduced with two open-channel which cover an extensive field of bio-detection applications. Gold (Au) is considered as an effective plasmonic ingredient. The transformation of light through the fiber core is coupled with the gold and stimulates SPR. The proposed PCF-SPR sensor reports the highest wavelength sensitivity (WS) of 7000 nm/RIU (refractive index unit) as well as an amplitude sensitivity (AS) of 593.61 RIU−1. It also acquires an increased sensor resolution of 1.43 × 10−5 RIU and a decent figure of merit (FOM) is 94.97 RIU−1. Additionally, the operating constraints of the sensor such as corresponding air-holes diameter, the pitch, gold layer (Au) thickness and open-channel radius are revised to improve detection performance. The overall measurement is carried out over a broad range of variations in refractive index (RI) from 1.33 to 1.40. The sensor's appreciable performance makes it suitable for bio-sensing applications.

In this paper, a novel photonic crystal fiber (PCF) is numerically characterized by finite element method (FEM) based mode solver software for bio-analyte sensing, particularly for detecting natural sucrose having a refractive index (RI) ranging from 1.29 to 1.42. The proposed PCF consists of a solid silica core and adjacent rectangular air holes in the cladding. To introduce the widely known surface plasmon resonance (SPR) phenomenon into the proposed sensor, the entire outer surface is covered by a thin gold film. The sensing methodology is appropriately addressed, and each of the designed parameters of the sensor structure is tuned sufficiently to find out the desired sensing performance. Considering RI change at the outer surface, appealing sensing performance such as maximum wavelength sensitivity of 216,000 nm/RIU and maximum amplitude sensitivity of 1138.52 RIU-1 are attained. In addition, the proposed sensor possesses a resolution of 4.63×10-7 RIU, linearity of 0.9891, the figure of merit of 1981.651 RIU-1, and detection accuracy of 0.019802 nm-1. However, except for sucrose detection, the promising sensing characteristics of the proposed sensor indicate its potential to be effectively used to detect biochemical and organic samples.© 2022 Optica Publishing Group under the terms of the Optica Publishing Group Publishing Agreement.

Microstructure fibers, integrating microfluidic channels and light guidance in one fiber, enable three-dimensional surface-enhanced Raman scattering (SERS) detection for large signal accumulation. However, the available fiber SERS probes are complicated to prepare and they are not reusable. In addition, light interacts with analytes in a form of an evanescent field, which is very weak. In this paper, we developed a SERS platform based on suspended-core photonic crystal fibers decorated with Ag/ZnO nanocomposites on the inner surface for direct, ultrasensitive, and reusable analyte detection. The unique configuration not only transfers a core-localized field to the liquid interface to greatly enhance the light–analyte interaction but also facilitates charge transfer to further improve the SERS detection sensitivity and degradation efficiency. The detection limit of crystal violet solution is 10–13 M, and the enhancement factor reaches 1011. The relative standard deviation is as low as 5.4%, ensuring the reproducibility of SERS detection. The probe has good photocatalytic performance and can degrade molecules under ultraviolet-light illumination within 20 min. This ultrasensitive and reusable SERS probe shows great application potential in rapid and in situ liquid detection. [ABSTRACT FROM AUTHOR]

This paper presents and numerically analyzes a refractive index sensor based on side-polished D-shaped two-channel photonic crystal fiber (PCF) and surface plasmon resonance (SPR). The effects of pore duty ratio, polishing depth, and thickness of a Nano-Titania sensitizing layer on sensor performance are studied, and the sensor performance is analyzed and optimized. The results show that the sensitivity of the Nano-Titania sensitized sensor can reach 3392.86 nm/RIU and temperature sensitivity of the sensor is increased to 1.320 nm/K, and the amplitude sensitivity of the unsensitized sensor can reach 376.76 RIU−1. In addition, the influence of titanium dioxide layer on the mode field diameter of PCF fiber core is also studied. It is found out that the sensor with a 50 nm thick titanium dioxide film has a larger mode fiber diameter, and is more conducive to coupling with single-mode fiber. Our detailed results contribute to the understanding of SPR phenomena in hexagonal PCF and facilitate the implementation and application of SPR-PCF sensors. [ABSTRACT FROM AUTHOR]

A grapefruit-shape hollow-core liquid infiltrated photonic crystal fiber (LI-PCF) is proposed and evaluated to identify the percentage of kerosene in adulterated petrol. The proposed hollow-fiber sensor is designed with Cyclo Olefin Polymer (Zeonex) and likely to be filled with different samples of petrol which is adulated by the kerosene up to 100%. Considering the electromagnetic radiation in THz band, the sensing properties are thoroughly investigated by adopting finite element method (FEM) based COMSOL Multiphysics software. However, the proposed sensor offers a very high relative sensitivity (RS) of 97.27% and confinement loss (CL) less than 10−10 dB/m, and total loss under 0.07 dB/cm, at 2 THz operating frequency. Besides that, the sensor also possesses a low effective material loss (EML), high numerical aperture (NA), and large Marcuse spot size (MSS). The sensor structure is fabrication feasible through existing fabrication methodologies consequently making this petrol adulteration sensor a propitious aspirant for real-life applications of petrol adulteration measurements in commercial and industrial sensing. [ABSTRACT FROM AUTHOR]

In this paper, we design a novel photonic crystal fiber (PCF) chemical sensor wherein the cladding structure is made of a steering-wheel (SW)-shaped large non-circular air-hole. In this PCF, we introduce the rectangular air holes in the core and they are filled with any one of the analytes, namely, water, ethanol and benzene. We use the full-vectorial finite element method (FEM) to optimize the structural parameters. Based on the numerical results, we find that the proposed sensor exhibits a high relative sensitivity of 92.8%, 93.2% and 93.4% for water, ethanol and benzene, respectively, at THz. Furthermore, we study the various optical characteristics of the proposed PCF, namely, birefringence, effective area and numerical aperture (NA). [ABSTRACT FROM AUTHOR]

An unstable bilirubin level in the human blood causes many dangerous health problems, such as jaundice, coronary artery disease, ulcerative colitis, and brain lesions. Therefore, the accurate and early detection of bilirubin concentrations in the blood is mandatory. In this work, a highly sensitive biosensor based on photonic crystal fiber (PCF) for monitoring bilirubin levels is proposed and analyzed. The sensor parameters, including relative sensitivity, effective mode area, confinement loss, and effective material loss, are calculated. The geometrical parameters are studied, and a modal analysis of the suggested sensor is carried out using the full-vectorial finite element method (FEM). The fabrication tolerance of the geometrical parameters is also studied to ensure the fabrication feasibility of the reported design. High sensitivities of 95% and 98% are obtained for the x-polarized and y-polarized modes, respectively. Furthermore, a small material loss of 0.00193 cm−1, a small confinement loss of 2.03 × 10−14 dB/cm, and a large effective mode area of 0.046 mm2 are achieved for the y-polarized mode. It is believed that the presented sensor will be helpful in health care and in the early detection of bilirubin levels in the blood. [ABSTRACT FROM AUTHOR]

A compact temperature-refractive index (RI) flat photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) is presented in this paper. Sensing of temperature and RI takes place in the x- and y- polarization, respectively, to avoid the sensing crossover, eliminating the need for matrix calculation. Simultaneous detection of dual parameters can be implemented by monitoring the loss spectrum of core modes in two polarizations. Compared with the reported multi-function sensors, the designed PCF sensor provides higher sensitivities for both RI and temperature detection. A maximum wavelength sensitivity of −5 nm/°C is achieved in the temperature range of −30–40 °C. An excellent optimal wavelength sensitivity of 17,000 nm/RIU is accomplished in the RI range of 1.32–1.41. The best amplitude sensitivity of RI is up to 354.39 RIU−1. The resolution of RI and temperature sensing is 5.88 × 10−6 RIU and 0.02 °C, respectively. The highest value of the figure of merit (FOM) is 216.74 RIU−1. In addition, the flat polishing area of the gold layer reduces the manufacturing difficulty. The proposed sensor has the characteristics of high sensitivity, simple structure, good fabrication repeatability, and flexible operation. It has potential in medical diagnosis, chemical inspection, and many other fields. [ABSTRACT FROM AUTHOR]

Photonic Crystal Fibers (PCF) have drawn a lot of interest due to their potential to produce a distinctive spectrum of optical properties that are just not feasible in common fiber types, whereas PCF can work in both conditions if the refractive index (RI) of the core is higher than the refractive index of the cladding In this case light is guided through total internal reflection (TIR), while in the second condition, the refractive index (RI) of the core is lower than the refractive index of the cladding, the light is guided through a photonic bandgap effect, which is not possible with conventional fibers. The surface plasmon resonance (SPR) is used in the sensor design. In this overview, an analysis of current advancements in photonic crystal fiber sensor design for sensing applications is presented, as also the effect of gold and silver nanoparticles and other types of material used to coat optical crystal fibers for sensors, the focus of this article uses of PCF for various sensing applications. such as thermal sensors, gas sensors, and biosensors. These PCFs are available in two types solid core and hollow core. Solid core photonic PCF has traditionally been utilized for sensing applications because the cladding channels can be filled with gas or liquid, acting as a useful form of evanescent wave sensing and also can coat the outer surface with plasmonic material depending on the surface plasmonic resonance phenomenon. Hollow core PCF delivers significant gains because of the presence of samples in the core. Hollow core PCF is used for sensor purposes by s filling the core with different types of liquid or gases where the majority of the light is contained, increasing the interaction between light and matter. Due to the exceptional properties that such photonic crystal fiber can give, more sensors are anticipated to be created in the future. The development of various optical sensing methods, their advantages, disadvantages, and potential for point-of-care applications are all thoroughly covered. [ABSTRACT FROM AUTHOR]

A new porous core PolyEthylene Terephthalate Photonic crystal fiber (PET-PCF) has been proposed that promises to demonstrate substantial optical nonlinearity with the SCG in the near-infrared region. The suggested structure has a diamond-shaped core, which allows for excellent confinement inside the core and aids in achieving an excellent nonlinear coefficient value of 6000 GW−1 km−1 and birefringence of the order of 10–4 at 1550 nm. The proposed material PET is exceptionally lightweight, efficient, shatterproof, and low cost with a very high nonlinear refractive index and simple to fabricate by using the usual stack-and-build process. The PET-PCF becomes a good nonlinear fiber due to the air-polymer combination. Nonlinear signal processing and supercontinuum production will be possible with the suggested fiber. [ABSTRACT FROM AUTHOR]

This paper presents a novel GaAs-filled five-ring circular-coated photonic crystal fiber (PCF) architecture with highly birefringent and nonlinear characteristics. The elemental simulation analyses are carried out in the COMSOL software v5.5, employing the finite element method (FEM) with a perfectly matched layer (PML) boundary condition to scrutinize a wide range of optical properties, such as birefringence (Br), nonlinear coefficient (NLC), effective mode area (EMA), confinement loss (CL), dispersion, etc. The simulated findings illustrate that for the optimized structural parameters, an ultra-negative dispersion, as well as an ultra-high Br and NLC of 0.187 and 2.06 × 106 W−1 km−1 can be sequentially acquired at 1.55 µm wavelength. Further, the developed PCF with ultra-high Br and NLC properties is conveniently fabrication friendly, which is a beneficial factor for probable practical utilization in terms of biosensing applications, as well as supercontinuum generation, polarization maintaining, nonlinear optics and so forth. [ABSTRACT FROM AUTHOR]

This study introduces a distinctive LiNbO 3 -based five-ring heptagonal-shaped photonic crystal fiber (PCF) geometry that demonstrates exceptionally high birefringence (Br) and nonlinear coefficient (NLC). Fundamental simulation studies are conducted through the COMSOL software utilizing the finite element method (FEM) with a perfectly matched layer (PML) boundary condition in order to comprehensively explore a variety of relevant optical characteristics, including birefringence, effective area, nonlinearity, core power fraction, dispersion, numerical aperture, confinement loss and so on. The simulation outcomes reveal an ultra-high Br and NLC of 0.081 and 5843.32 W - 1 K m - 1 sequentially, at the operative wavelength of 1.55 μ m. The designed PCF with ultra-high Br and NLC features can be fabricated suitably, which is an advantageous aspect for potential prospective utilization in polarization-maintaining, nonlinear optics, supercontinuum generation, etc. [ABSTRACT FROM AUTHOR]

Triangular lattice-based hexagonal photonic crystal fiber (PCF) has been introduced with high negative dispersion and nonlinearity. Dispersion and nonlinearity are numerically examined by using the finite element method. A maximum negative dispersion of − 1054.73 ps/(nm km) with a high nonlinearity of 136.44 W−1 m−1 is accomplished at 5.6 μm. The negative dispersion curve covers a broad mid-infrared range from 3.2 to 10 μm. The simulated results reveal that the reported PCF is appropriate for dispersion compensation and nonlinear optics applications such as supercontinuum spectrum, wavelength conversion, etc. [ABSTRACT FROM AUTHOR]

A high-performance photonic crystal fiber sensor for sulfuric acid detection is designed and investigated, undertaken through a full vector Finite Element Method on COMSOL Multiphysics software to establish the optical properties of effective refractive index, power fraction, relative sensitivity, confinement loss, chromatic dispersion, and propagation constant. Different aqueous sulfuric acid concentrations of 0%, 10%, 20%, 30%, and 40% were selected as the test analytes. The dimensions of two cladding rings of the hexagon- and circular-shaped air holes and a circular core hole denoted outstanding outcomes of relative sensitivity and confinement loss. At 1.1 µm optimum wavelength, 0%, 10%, 20%, 30%, and 40% sulfuric acid concentrations depict relative sensitivities of 97.08%, 97.67%, 98.06%, 98.39%, and 98.67%, respectively, and confinement losses of 1.32 × 10−12 dB/m, 4.11 × 10−12 dB/m, 1.46 × 10−12 dB/m, 6.34 × 10−12 dB/m, and 2.12 × 10−12 dB/m, respectively. [ABSTRACT FROM AUTHOR]

This paper proposes and analyzes a simple surface plasmon resonance (SPR)-based elliptical air hole photonic crystal fiber (PCF) sensor. The fiber structure comprises an analyte channel of the fiber surface coated with a gold layer on the flat surface and the fiber's external surface. Numerical simulations are conducted using the finite element method (FEM) with an external sensing approach. We found that the thickness of plasmonic material (Au) is the most crucial factor that affects the full width at half maximum (FWHM) and confinement loss amplitude. We also demonstrated that the proposed elliptical air hole SPR-PCF is superior to circular air hole SPR-PCF in terms of confinement loss and FWHM. According to the wavelength interrogation technique, the simulation results show that the designed SPR-PCF sensor can attain a maximum sensitivity of 116,500 nm/RIU and a resolution of 8.58 × 10−7 RIU (RIU: refractive index unit) for the analyte RI of 1.395. We believe the proposed SPR-PCF sensor can be a potential candidate for biomolecular and biological analyte detection. [ABSTRACT FROM AUTHOR]

In this study we demonstrate a high-performance polarization rotator (PR) based on flat-shaped photonic crystal fiber. The flat surfaces of the fiber are plated on gold films as electrodes, and the core of the structure is filled with liquid crystal. The polarization rotation characteristics of the flat-shaped fiber can be effectively adjusted by applying external voltage. The optical properties are analyzed using the finite element method (FEM). The results show that the magnitude of the modulation voltage is closely related to the thickness of the flat fiber. When the fiber thickness is 20 μm, only 100 V is required to achieve the highest PR performance. In the wavelength of the 1.55 μm band (~200 nm bandwidth), the conversion length of the PR is only 3.99 μm, the conversion efficiency is close to 100%, and the minimum crosstalk value is −26.2 dB. The presented PR, with its excellent performance, might enable promising applications in the communication system and the photonic integrated circuits. [ABSTRACT FROM AUTHOR]

In this work, highly sensitive D-shaped photonic crystal fiber (PCF) sensor with plasmonic pyramid grating is introduced and analyzed. The sensing mechanism depends on the coupling between the fundamental core mode and the surface plasmon mode around the plasmonic pyramid grating. The resonance frequency depends on the analyte refractive index (RI) which can be employed to detect the analyte RI changes. The geometrical parameters of the proposed PCF and gold pyramid grating are studied to enhance the RI sensor sensitivity. The simulation results are obtained using full vectorial finite element method. The suggested sensor has higher sensitivity of 5200 nm/RIU than 3340 nm/RIU of the conventional grating design through the studied RI range from 1.355 to 1.385. Therefore, the reported RI sensor can be used for basal cancer cell detection with normal and cancerous cells' refractive indices of 1.36 and 1.38, respectively. Additionally, linear performance is achieved using the reported design. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrated a method of filling the air holes of a photonic crystal fiber (PCF), coated with gold film, with magnetic fluid (MF) to enhance the Surface Plasmon Resonance (SPR). The simulation results show that at the wavelength of 1260-1675 nm, the minimum loss coefficient of the y-polarization mode is 4.7 times that before filling with MF, and the x-polarization mode is 0.45 times greater. Then, based on this method, we designed a polarizing filter with a core diameter of 9 µm. The numerical simulation results indicate that it not only maintains the same core diameter as the single-mode fiber, but also has a larger bandwidth and a higher extinction ratio (ER). Additionally, we can optimize its ER at a specific wavelength by adjusting the magnetic field.

We propose a ring-core photonic quasi-crystal fiber (RC-PQCF) featuring a ring-shaped fiber core and two symmetrical SiO2 stress-applying parts (SAPs). By optimizing the mole percentage of GeO2 and geometrical parameters of the fiber, the design supports 34 full vector polarization modes (FV-PMs). The effective refractive index difference ($\Delta {n_{eff}}$) of adjacent FV-PMs is larger than $1.07 \times {10^{ - 4}}$ at 1550 nm. The confinement loss (${\mathrm{\alpha }}$) of FV-PMs is less than ${10^{ - 6}}$, which is sufficient to confine the light field in the ring-core. Through numerical analysis, broadband performance is investigated subsequently in the 1500–1600 nm. The dispersion (${D_\lambda }$) of FV-PMs is less than $138.14{\mathrm{\ ps}} \cdot {\mathrm{n}}{{\mathrm{m}}^{ - 1}} \cdot {\mathrm{k}}{{\mathrm{m}}^{ - 1}}$ and maintains a flat trend. The mode field area (${A_{eff}}$) of FV-PMs is larger compared to single mode fibers and the nonlinear coefficient (${\mathrm{\gamma }}$) of FV-PMs is within ($6.97 \times {10^{ - 4}}$, $1.54 \times {10^{ - 3}}$) ${{\mathrm{m}}^{ - 1}} \cdot {{\mathrm{W}}^{ - 1}}{\mathrm{\ }}$ in the 1500–1600 nm. The fiber is a promising design for mode division multiplexing (MDM) that supports the MIMO-free processing and improves the transmission capacity and spectral efficiency.

An all-fiber supercontinuum (SC) laser source with 50.7 W average output power and spectrum ranging from 500 nm to 2400 nm is demonstrated. With the generation of high peak power nanosecond pulses and photonic crystal fiber (PCF) in the self-Q-switched fiber laser, the output SC shows good spectral width and flatness which has a 20 dB bandwidth of 1900 nm except the 1064 nm peak. The effect of the PCF length on the spectral characteristics and output power of SC were carefully studied. To the best of our knowledge, this is the highest power of SC generated in a single-stage fiber laser with such a broadband spectrum. This ultra-compact SC generation method has the merits of simple structure, low cost and good robustness, which provide an easily available SC generation method for various practical applications.

Based on few-mode fiber (FMF) and photonic crystal fiber (PCF), a new temperature sensor with a FMF-PCF-FMF hybrid construction has been developed. Furthermore, the sensor has a longitudinally symmetrical structure that makes it have a flexible sensor head, which enhances the practical performance. Simulated results show that there are three resonant peaks with extinction ratio above 18 dB in the wavelength from 1630 nm to 1720 nm, and the temperature can be measured by calculating wavelength shift of resonant peaks. The experimental results show that the temperature sensitivity of the proposed sensor is as high as 38.6 pm/°C when the temperature ranges from 20°C to 80°C. Meanwhile, the strain sensitivity of the proposed sensor is as low as −0.457 pm/μϵ when strain ranges from 0 to 3000 μϵ. The high temperature sensitivity and ultralow strain sensitivity indicate that the proposed sensor can effectively eliminate the cross-sensitive issue of temperature and strain. In addition to excellent sensing performances, simple and compact structure make the proposed sensor be potential in practical applications.