Lattice Photonic Crystal Fiber Research Articles

Characteristics study of a dual-wavelength polarization filter based on gold-filled square lattice photonic crystal fiber

This study proposes a polarization filter based on gold-filled photonic crystal fiber (PCF) with a square lattice structure. Utilizing the finite element method (FEM), the filtering characteristics of the model were numerically simulated. The dispersion relation and loss characteristics of this structure were analyzed, and the optimal structural parameters were obtained through structural adjustments. Furthermore, the performance of the filter was evaluated under a 2% variation in manufacturing tolerances for gold film thickness (), air hole spacing (), and air hole diameters () and (). Results indicated that at the 1310 nm and 1550 nm communication windows, the confinement losses of the filter were 1354.6 dB/cm and 869.04 dB/cm, respectively, while the losses for the -polarization were merely 16.97 dB/cm and 0.98 dB/cm. When the filter length was set to 0.5 mm, the maximum extinction ratios (ERs) for the two windows reached 588.2 dB and 370.6 dB, and the filter bandwidth extended to 640 nm. Moreover, the characteristics of the filter under manufacturing tolerances were computed, revealing that the filter’s performance remained stable and feasible despite manufacturing errors. The proposed rectangular gold-coated PCF is anticipated to have broad applications in optical fiber communication and optical information processing.

Study on optical properties of hexagonal lattice photonic crystal fibers infiltrated with heavy water

In this paper, we analyzed a PCF made from fused silica glass, with a core filled with heavy water. The guiding properties of proposed fibers in terms of effective refractive index, attenuation, and dispersion of the fundamental mode were studied and optimized setups were selected and analyzed in detail. After 25 simulations, we determined two structures possessing optimal dispersion with the lattice constant (Ʌ) and the filling factor as follows: Ʌ = 1.1 µm, d/Ʌ = 0.92 for #F1 and Ʌ = 1.4 µm, d/Ʌ = 0.92 for #F2. Besides, high nonlinearity and low confinement loss are also outstanding points in our model. Thanks to these advantages, the proposed fibers have been targeted for flat and smooth broadband supercontinuum (SC) generation for near-infrared applications.

Numerical Investigation of Optical Properties in Carbon Tetrachloride-Filled Photonic Crystal Fibers

In this work, we design circular lattice photonic crystal fibers using Lumerical Mode Solution software, its hollow core filled with carbon tetrachloride. Optical properties including effective refractive index, chromatic dispersion, nonlinearity, and fiber loss were investigated numerically in detail based on solving Maxwell's wave equations. The small effective mode areas of only a few µm2, and confinement loss as low as 14.799 dB/m at specific pump wavelengths were obtained. It was found that near-zero ultra-flattened chromatic dispersion with fluctuations of ±0.44 ps/nm.km spans from 1300 to 1830 nm. Three photonic crystal fibers with optimal structure and features were suggested for broadband supercontinuum generation orientation.

Broadband supercontinuum generation in hollow-core photonic crystal fibers infiltrated with chloroform

The chloroform-infiltrated square lattice photonic crystal fibers (PCFs) are designed with the difference of the air hole diameters in the cladding to improve chromatic dispersion and nonlinear properties. Based on numerical simulation results, two optimal structures with flat dispersion, high nonlinear coefficient, and small confinement loss are used for supercontinuum (SC) generation. The first fiber has an all-normal dispersion regime, a nonlinear coefficient of 486.355[Formula: see text]W[Formula: see text].km[Formula: see text] generating an SC spectrum of 640.3[Formula: see text]nm within 30 dB levels at a pump wavelength of 0.945[Formula: see text][Formula: see text]m with peak power as low as 1.44[Formula: see text]kW. With anomalous dispersion properties, the second fiber gives a very broad SC spectrum of 1471.8[Formula: see text]nm within 30 dB levels at a 1.4[Formula: see text][Formula: see text]m pumping wavelength with a peak power of 20[Formula: see text]kW. All-fiber SC sources operating with low-power pump lasers can use these fibers to effectively replace glass-core fibers.

Supercontinuum spectra above 2700 nm in circular lattice photonic crystal fiber infiltrated chloroform with the low peak power

Supercontinuum spectra above 2700 nm in circular lattice photonic crystal fiber infiltrated chloroform with the low peak power

Broadband supercontinuum generation in a square lattice photonic crystal fiber with C6H6-core using low pump power

Broadband supercontinuum generation in a square lattice photonic crystal fiber with C6H6-core using low pump power

Highly coherent supercontinuum generation in circular lattice photonic crystal fibers using low-power pulses

Two structures of circular lattice Photonic Crystal Fibers (PCFs) based on Ge20Sb15Se65 (GSS) material have been proposed for a highly coherent broadband supercontinuum generation (SCG) in the mid-infrared region. Numerical studies using the Finite Difference Eigenmode (FDE) solver on both structures show that the fundamental modes are well confined in the core while the confinement losses are very low. Also, the high nonlinear coefficient of 22.01 W−1m−1 and 17.99202 W−1m−1 for the two structures ensure that these structures can accomplish high nonlinear activity. It has been found that broadband supercontinuums (SCs) spanning from 0.45 μm to 5.3 μm and 0.48 μm to 6.5 μm can be generated using a hyperbolic secant pulse of 0.5 kW. The proposed structures also show very good structural tolerance to optical properties that prevents any radical shift in SC spectra owing to potential fabrication mismatch.

Multifunctional chalcogenide (As[formula omitted]S[formula omitted], As[formula omitted]Se[formula omitted]) dual-core photonic crystal fiber with elliptical air-hole for mid-IR optical communications: Design and analysis

This work presents an integrated design of a multifunctional hexagonal lattice dual-core photonic crystal fiber (DC-PCF) with elliptical air-hole surrounding the cores, using two different chalcogenides (As2S3-Arsenic sulfide and As2Se3-Arsenic selenide) for mid-infrared (mid-IR) optical communications. Numerical study of both chalcogenide DC-PCF structures exhibits that the DC-PCFs are highly birefringent and single-moded in the mid-IR wavelength region (5 μm to 13 μm) of optical communications. Results show that both DC-PCFs can be operated as polarization splitters at 9 μm wavelength for two orthogonal modes and they can also be used as WDM MUX-DeMUX for both X- and Y-polarization fundamental supermodes separating 9 μm/10 μm wavelengths (As2S3 DC-PCF) and 8 μm/9 μm wavelengths (As2Se3 DC-PCF). Moreover, the proposed chalcogenide DC-PCFs, with much lower splice loss at 8–10 μm wavelength region, are appropriate enough for the practical applications in integrated optics and photonics.

Temperature-based dispersion compensating ability of a photonic crystal fiber

The effects of temperature on the dispersion properties of a square lattice photonic crystal fiber (PCF) have been studied. Holes in the cladding part of PCF are packed with a semiconducting material, InSb, whose characteristics depend upon temperature in the terahertz optical frequency. The effective index of PCF is calculated with the help of a semivectorial finite difference technique. Using the effective index values, computation of chromatic dispersion parameters is done, which are plotted against wavelength. Four temperatures have been considered in our work from 290 to 335 K in equal steps. The results depict that as the temperature rises, the values of effective indexes of PCF decrease while dispersion of the fiber increases. In places where temperature is not constant and keeps varying, this type of PCF can be installed for multiple optical channel dispersion compensating applications. It has also been observed that with the change in surrounding temperatures, mode carrying capacity of the fiber remains unaffected, which makes this fiber suitable for special applications, such as distributed perimeter sensing of chemical plants.

Design of novel circular lattice photonic crystal fiber suitable for transporting 48 OAM modes

Design of novel circular lattice photonic crystal fiber suitable for transporting 48 OAM modes

Polarization-independent wavelength splitter based on silicon nanowire embedded dual-core pentagonal lattice photonic crystal fiber for optical communication systems

A silicon nanowire embedded dual-core pentagonal photonic crystal fiber (PCF)-based polarization-independent wavelength splitter is proposed. The proposed PCF structure is analyzed using the finite element method. The wavelength splitting behavior of the PCF is investigated using the coupled-mode theory. The structural parameters of the PCF are optimized to achieve a coupling length ratio of 2. For the proposed PCF of length 102 μm, the cross-talk (CT) of −48.27 and −61.54 dB and CT bandwidth of 29.3 and 37.7 nm at 1.3 and 1.55 μm for X-polarization mode is achieved. However, the proposed PCF of length 115.5 μm attained the CT of −42.83 and −46.74 dB and CT bandwidth of 27.6 and 34.5 nm at 1.3 and 1.55 μm, respectively for Y-polarization mode. The polarization-independent wavelength splitter is achieved with the proposed PCF of length 108.75 μm. The proposed PCF-based wavelength splitter will be an inevitable candidate for integrated optical systems.

Low loss flat dispersive hexagonal porous core THz fiber

A low loss porous core hexagonal lattice photonic crystal fiber (PCF) is proposed. Design procedure and properties are investigated in terahertz (THz) band. We explore different important properties of the PCF to evaluate the merit of proposed design. Circular air hole at the center surrounded by rectangular air hole array in the fiber core is designed in such a way that maximizes the core porosity of the fiber. The structure of cladding, on the other hand, is designed with a large hexagonal air hole array with tiny isolation width, resulting in a minimum total loss. The bulk material loss is diminished by 85.8% using core porosity of 80%. Numerical result shows relatively low confinement loss at 1 THz with flattened dispersion. Withal, single-mode propagation is exhibited in the proposed PCF design. The novel approach of this proposed PCF is unique to ensure good confinement in the core with a reasonable amount of power fraction.

Irregular hexagonal core based surface plasmon resonance sensor in near-infrared region

In this work, a highly sensitive yet simple hexagonal photonic crystal fiber (PCF) based surface plasmon resonance (SPR) refractive index (RI) sensor is proposed. The proposed structure consists of twelve purely circular air-holes to render the fabrication process easily realizable. For the feasibility of operation, the target analyte, and the plasmonic material, Indium Tin Oxide (ITO) are employed around the outer surface of the sensor. The performance of the sensor is numerically analyzed using the full-vectorial finite element method (FEM) for different fiber geometric parameters and RI variations. A step-by-step design procedure has been followed starting from the regular hexagonal lattice PCF structure. The optimal sensor performance is obtained by tuning the geometric parameters over the relevant numeric range. It is shown that the proposed sensor achieves a maximum wavelength sensitivity of 37000 nm/RIU and a maximum amplitude sensitivity of 407.285 RIU-1for a dielectric RI range from 1.33 to 1.40 in the near-infrared wavelength regime (1470 nm − 2220 nm). Apart from this, to ensure high detection accuracy of small refractive index (RI) changes, the sensor achieves the highest wavelength resolution and amplitude resolution of 2.70×10-6 RIU and 2.46×10-5RIU-1, respectively, along with the highest Figure of Merit of 217.65 RIU-1. Hence, the proposed PCF-SPR sensor can potentially be used to detect unknown refractive indices for various applications including biosensing.

High birefringence and broadband dispersion compensation photonic crystal fiber

Abstract We propose a perfectly square lattice photonic crystal fiber (PCF) which shows high birefringence and negative dispersion. To set up high asymmetry in the core, dual line imperfection is considered where the fill fraction ratio and defect air hole diameter exhibit significant impact on dispersion and birefringence. Numerical analyses of guiding properties of the proposed PCF are done using finite element method with perfectly matched layer boundary condition from 1.2 to 1.8 μm wavelength. The optimized square lattice PCF presents high birefringence of 2.48 × 10−2 and dispersion of −777.66 (ps/nm.km) at 1.55 μm wavelength. In addition, the proposed PCF offers ultra-low confinement and insertion loss at 1.55 μm wavelength. Moreover, −0.45 (ps/nm2.km) dispersion slope and 0.0045 nm−1 relative dispersion slope are observed at 1.55 μm wavelength. Additionally, the proposed PCF maintains dispersion and birefringence variation of ±30 (ps/nm.km) and ±0.00001 between 1.5 and 1.6 μm wavelength ranges, respectively. Furthermore, the proposed PCF shows high quality factor and low bit error rate at 10 dBm input power. We believe the proposed square lattice PCF can be deployed in wavelength division multiplexing based optical fiber transmission system for wide-band dispersion compensation.

Design and Simulation of Photonic Crystal Fiber for Liquid Sensing

A simple hexagonal lattice photonic crystal fiber model with liquid-infiltrated core for different liquids: water, ethanol and benzene, has been proposed. In the proposed structure, three air hole rings are present in the cladding and three equal sized air holes are present in the core. Numerical investigation of the proposed fiber has been performed using full vector finite element method with anisotropic perfectly match layers, to show that the proposed simple structure exhibits high relative sensitivity, high power fraction, relatively high birefringence, low chromatic dispersion, low confinement loss, small effective area, and high nonlinear coefficient. All these properties have been numerically investigated at a wider wavelength regime 0.6–1.8 μm within mostly the IR region. Relative sensitivities of water, ethanol and benzene are obtained at 62.60%, 65.34% and 74.50%, respectively, and the nonlinear coefficients are 69.4 W−1 km−1 for water, 73.8 W−1 km−1 for ethanol and 95.4 W−1 km−1 for benzene, at 1.3 µm operating wavelength. The simple structure can be easily fabricated for practical use, and assessment of its multiple waveguide properties has justified its usage in real liquid detection.

Modeling of low non-linearity and low confinement loss photonic crystal fiber by introducing asymmetric defect structures

In this article, confinement loss in hexagonal lattice photonic crystal fiber has been investigated, by using COMSOL Multiphysics based on finite element method. The proposed structure consists of four circular air holes rings, where three circular air holes near the center are replaced by elliptical air holes, which have a major and minor diameter. The Confinement loss was studied in term of minor diameter and wavelength in the range of about 1200–1800 (nm). We realized that the rise of minor diameter lead to decreases of imaginary part of effective index and therefore the confinement loss reduces.

Dual-core gold coated photonic crystal fiber plasmonic sensor: Design and analysis

A simple circular lattice dual-core photonic crystal fiber (PCF) based plasmonic sensor is numerically investigated in this paper within the visible to near-infrared (450 nm to 1150 nm) region. To examine the sensing performances and the guiding properties of the sensor, Finite Element Method (FEM) based mode solver software is applied in the presence of Perfectly Matched Layer (PML) and Scattering Boundary Conditions (SBC). Chemically inoperative plasmonic material gold is deposited at the outer surface of the raised sensor to create the Surface Plasmon Resonance (SPR) effect. This sensor proffers the maximum wavelength sensitivity of 11,200 nm/RIU and the amplitude sensitivity of 505.037RIU-1 according to the simulation results. It also allows the maximum Figure of Merit (FOM) of 275RIU-1 along with the sensor resolution of 8.92×10-6 RIU for wavelength sensing within the RI range of 1.33 to 1.44. Moreover, the impact of various structural parameters (e.g. air hole, pitch, plasmon layer thickness) on the sensing performance of the structure is also described in detail. All these results indicate that this fabrication friendly, highly sensitive sensor can be a promising applicant in the field of biosensing.

Design and analysis of birefringent SPR based PCF biosensor with ultra-high sensitivity and low loss

A novel, perfectly hexagonal lattice photonic crystal fiber (PCF) biosensor based on surface plasmon resonance (SPR) is proposed in this research. To design and investigate the influence of several initial geometric parameters on the sensing properties of the sensor, finite element method (FEM) based commercially available COMSOL Multiphysics version 5.3a is used. A 20 nm layer of chemically stable plasmonic material gold (Au) is used to make the excitation possible between the core and plasmonic modes. A thin film of TiO2 is placed on the glass surface, which allures the field from the core guided mode and also assists in the adhesion of gold (Au) on the fiber. By exploiting the geometric parameters, simulation results show a maximum wavelength sensitivity of 16,000 nm/RIU (Refractive Index Unit) and 17,000 nm/RIU for x-polarization and y-polarization respectively due to the dielectric refractive index (RI) variation from 1.33 to 1.41. It is shown that the highest obtained amplitude sensitivity of the proposed sensor reaches 4596 RIU−1 and 4557 RIU−1, respectively, for x-polarization and y-polarization with the maximum loss of 3.73 dB/cm and 4.48 dB/cm. Additionally, the maximum sensor resolution (amplitude) of 2.18 × 10-6 and 2.19 × 10-6, the maximum sensor resolution (wavelength) of 6.25 × 10-6 and 5.88 × 10-6 for x- and y-polarization modes respectively and maximum birefringence of 8.8984 × 10-4 is attained. Due to its high sensing characteristics, the mentioned sensor is expected to contribute to the accurate detection of biological and organic chemical analytes.

Gold-coated photonic crystal fiber based polarization filter for dual communication windows

Future optical integrated circuits can be created by overcoming the diffraction limit of light that imposes a lower bound on the size limit of optical devices and plasmonics can meet the desired requirements of producing very compact optical devices. A plasmonic based compact and broadband polarizer, capable of producing single polarized ray concurrently around the two communication windows of 1.31μm and 1.55μm, based on hexagonal lattice photonic crystal fiber is proposed. The results show that the confinement loss of x- and y-polarized modes are 1014.05 dB/cm and 0.048 dB/cm, respectively, at the wavelength of 1.31μm meaning that x-polarized mode is 20812 times lossier than y-polarized mode. Similarly, the achieved loss ratio between two orthogonal polarized modes is 6439 at the wavelength of 1.55μm. In addition, the filter can also maintain a broad bandwidth of over 800 nm by keeping crosstalk greater than 20 dB for the device length of 100μm. The bandwidth and maximum crosstalk value can be extended by loosing compactness of the device. The simultaneous filtering performance around two communication windows with broad bandwidth and compact in length makes the proposed filter a suitable candidate for optical communication and sensing system.

A Comparative Analysis between Low Loss Kagome Structured THz Hollow Core and Porous Core PCF

This paper presents a comparative study between a porous core kagome lattice photonic crystal fiber (PCF) and a air filled Hollow core kagome lattice PCF (HC-PCF), which acts as a low loss and polarization maintaining tera hertz (THz) waveguide. Proposed PCFs are simulated using finite element method (FEM), including the effective material loss (EML), confinement loss and single mode propagation. Cyclic olefin copolymer, also known as TOPAS material have been chosen for the air micro structured inhibited coupled design of PCF which has the lowest bulk material absorption loss of 0.2 cm-1. Expressions are given to asses this optimization and the result are shown for the variation of core diameter from 425 μm to 600 μm for both the Hollow core and porous core PCFs and for the comparison with porous core the optimized porosity taken as 60% and 70% along with the frequency of 1THz. The analysis results approximately 80% to 90% improvement in losses in case of passing THz waves through HC-PCF rather than Porous core PCF. By varying core parameter such as core porosity and core diameter and strut width at 1THz, the goal is to show an optimized solution consisting of low EML and confinement loss for both of the wave guidance and comparing the results to analyze and hence finding out a better solution.