Low Confinement Loss Research Articles

Numerical Modeling of a Rectangular Hollow-Core Waveguide for the Detection of Fuel Adulteration in Terahertz Region

A petrol adulteration sensor based on a rectangular shaped hollow-core photonic crystal fiber is proposed and numerically analyzed in the terahertz regime. The performance of the proposed sensor was evaluated when it is employed to characterize different kerosene mixtures. In this research, the adulterated fuel sample is filled in the rectangular hollow channel and the electromagnetic signal of the terahertz band is also driven through the same channel. The received signal after the interaction of fuel with the terahertz signal will advise the refractive index of the fuel oil inside the core, which will also bear the information of how much extrinsic component is present in the fuel. The finite element method based simulation shows that the proposed sensor can reach a high relative sensitivity of 89% and presents low confinement losses at 2.8 THz. The reported sensing structure is easily realizable with the conventional manufacturing techniques. Consequently, this proposed fiber may be treated as an essential part of real-life applications of petrol adulteration measurements.

Theoretical analysis of large negative dispersion photonic crystal fiber with small confinement loss.

Solid core circular and octagonal photonic crystal fibers (CPCF and OPCF) are proposed for analyzing different guiding properties such as dispersion, effective mode area, nonlinearity, and confinement loss from 0.8 to 2.6 µm wavelength. The proposed structures use three different types of background materials: SF10, BK7, and silica. Moreover, the fill fraction is varied by changing the diameter of the air hole where the lattice pitch is unchanged. The proposed PCFs show a high negative dispersion with low confinement loss and small effective mode area. In the proposed design, the finite element method with a perfectly matched layer absorbing boundary condition is used. At 1.8 µm wavelength with 0.6 fill fraction, the maximum negative dispersion of -922.5ps/(nm.km) is observed for CPCF when the background material is SF10. In addition, at this particular wavelength, the confinement loss is observed to be very small. Moreover, -560.12ps/(nm.km) dispersion is found for the similar condition at 1.55 µm wavelength. On the other hand, using BK7 as the background material, -706.77ps/(nm.km) dispersion is found at 1.55 µm wavelength for CPCF. Results also imply that CPCF shows better performance than OPCF for a wide wavelength range. Furthermore, at 1.55 µm wavelength, silica-based glass exhibits maximum dispersion, whereas increasing wavelength flint type glass shows the similar result. Analyzing different guiding properties of PCFs has significant impact on broadband dispersion compensation applications, especially using SF10.

Design and FEM analysis of pentagonal photonic crystal fiber for highly non-linear applications

A Pentagonal Photonic Crystal Fiber (P-PCF) injected with $$ {\text{As}}_{2} {\text{S}}_{5} $$ in elliptic core has been propounded by FEM technique. The simulation is carried out by perfectly matched layer using COMSOL Multiphysics software. Several features of the PCF have been analyzed as such nonlinearity, confinement loss, birefringence, effective mode area, power fraction, numerical aperture and dispersion by synthesizing the shape of the cladding holes and the elliptic core. The P-PCF renders a higher nonlinear coefficient of 8000 $$ {\text{W}}^{ - 1} \,{\text{km}}^{ - 1} $$ , numerical aperture of 0.44, power fraction of 84% and lower confinement loss of $$ 10^{ - 7} $$ at 1.00 μm wavelength. Furthermore, higher birefringence and near zero dispersion are also gained. A perfect geometric fabrication and exclusive properties of chalcogenide glass is used as a core makes the PCF so dynamic in polarization controlling schemes, super continuum systems as well as nonlinear fields.

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.

Novel design of dual guided photonic crystal fiber for large capacity transmission in high-speed optics communications with supporting good quality OAM and LP modes

In this article, we propose, investigate, and analyze a novel designed two guided modes regions ring-core photonic crystal fiber (PCF) with relatively greater effective refractive index separation and also high isolation value which can be negligible the crosstalk among the guided channels. The designed PCF can be well supported up to 76 orbital angular momentum (OAM) modes and 6 linear polarization (LP) modes over 800 nm bandwidth. The background and ring-core materials of the proposed PCF are silicon and Shcott sulfur difluoride (SF2) glass, respectively. All characteristic features of the proposed PCF are successively analyzed using the finite element method (FEM) and the perfectly matched layer (PML) as a boundary condition within the COMSOL Multiphysics simulator. The designed PCF possess the good propagation features because the results show that the better mode quality (96%), the isolation value is kept above 72 dB that produces the very low crosstalk between the guided channels, high numerical aperture, relatively flat and small dispersion variations, and low confinement loss, etc. Therefore, these outstanding properties of the designed PCF prove that it has potential applications to enable the large-capacity transmission along with the high-speed optics communications.

Hexagonal photonic crystal Fiber (H-PCF) based optical sensor with high relative sensitivity and low confinement loss for terahertz (THz) regime

This paper presents an analysis on a hexagonal cladding with a rotated-hexa core in photonic crystal fiber (H-PCF) based optical sensor formation with simultaneously minimal confinement loss and higher sensitivity for chemical sensing functions. The numerical assessment of the designed structure is achieved with the procedure of finite element method (FEM) and perfectly matched layers (PML) boundary condition in the comsol multiphysics software tool. As per FEM numerical analysis, the proposed PCF sensor presents the extreme relative sensitivity at 81.46%, 82.26% and 79.22% for three chemicals at 1 terahertz (THz) such as Ethanol (n = 1.354), Benzene (n = 1.366) and Water (n = 1.330), respectively. Moreover, at 1 terahertz (THz) the low confinement losses are 5.85 × 10−08, 6.07 × 10−08 and 5.84 × 10−08 dB/m for similar three chemicals. The effective area, the effective mode index and the total power fraction are also elaborately explained. Furthermore, we hope that our proposed structure can be operated intensely in the field of biomedical, bio-sensing experiments and industrial applications in terahertz (THz) waveguide technology.

TOPAS based porous core photonic crystal fiber for terahertz chemical sensor

This paper contributes a novel design of photonic crystal fiber (PCF) with a combination of porous core structure and TOPAS as background material is proposed for chemical sensor in terahertz regime. A finite element method (FEM) has been used for investigation of the optical properties such as relative sensitivity, power fraction (PF), effective area, numerical aperture (NA) and confinement loss of the proposed structure. The findings of the simulations show that the proposed structure provides high relative sensitivity with low confinement loss for sensing different chemical substances like ethanol, benzene, and water. The relative sensitivity of the proposed sensor is 70 %, 68.59 % and 67.62 % for benzene, ethanol, and water, respectively at a frequency of 1.14 THz. Confinement loss of the proposed sensor has the order of 10−11 dB/m, which is very low and therefore convenient for practical applications as chemical sensor. In addition, V-parameter, Marcuse spot size (MSS) and Beam divergence (BD) are also carefully examined from 0.2 THz to 1.3 THz. The proposed sensor is mainly used to detect toxic chemicals for commercial purposes.

Design and analysis of a highly sensitive octagonal hollow core photonic crystal fiber for chemical sensing

Due to the dire need to monitor, sense, and control useful and harmful chemicals for industrial, environmental, and biomedical purposes, chemical sensing has become an eminent topic among researchers. Hence, we focus mainly on a modified kagome design with a relatively high sensitivity of 99.8%, effective material loss of 0.000263 cm − 1 for constant absorption loss, and 0.0004204 cm − 1 for variable absorption loss and low confinement loss of 2.117 × 10 − 17 cm − 1 investigated with the help of the full vector finite element method in Comsol multiphysics using water, ethanol, and benzene as analytes while considering other parameters, such as nonlinearity, dispersion, numerical aperture, and effective area which are equally investigated and discussed. The results obtained are tabulated and compared with recent works published.

Numerical Analysis of Supercontinuum Generated Microstructured Optical Fiber with all Normal Chromatic Dispersion

A micro-structured photonic crystal fiber (M-PCF) with all normal chromatic dispersion has been proposed for supercontinuum spectrum generation which is applicable in optical transmission and optical coherence tomography applications. Calculations of its different properties using finite difference method have shown that the proposed M-PCF has a high nonlinear coefficients at 1.06 μm, 1.30 μm and 1.55 μm wavelength with flattened chromatic dispersion, low confinement losses and broad supercontinuum spectrum. Moreover, it has been shown that the proposed design obtain high power and short fiber length at 1.06 μm, 1.30 and 1.55 μm center wavelengths by propagating sech2 picosecond optical pulses with 1.0 ps pulse width at a full width at half maximum.

Design of a chemical sensing circular photonic crystal fiber with high relative sensitivity and low confinement loss for terahertz (THz) regime

This paper contributes a novel proposal of a chemical sensor (CS) that is based on the elliptical rotated-hexacore photonic crystal fiber (ERH-PCF) for several chemical substances in the terahertz (THz) frequency regime. A full-vectorial finite element method (FEM) and perfectly matched layer (PML) frontier complaint are used to design this circular photonic crystal fiber (C-PCF) on software tools, and all numerical results in terahertz (THz) waveguide are achieved successfully. The proposed sensor shows maximum relative sensitivity (RS) that is 70.51%, 71.11% and 68.08% and less confinement loss that is 2.53 × 10-03 dB/m, 2.77 × 10-06 dB/m and 1.07 × 10-02 dB/m with response to Ethanol (n = 1.354), Benzene (n = 1.366) and Water (n = 1.330) at 1 THz frequency respectively. Here, total power fraction (TPF), effective mode index (EMI), and effective area (EA) are also discussed details in consideration of the context of different industrial and medical applications.

Design and analysis of a chemical sensing octagonal photonic crystal fiber (O-PCF) based optical sensor with high relative sensitivity for terahertz (THz) regime

This article represents a new structure of octagonal cladding with a rotated-hexa core in photonic crystal fiber (O-PCF) for chemical sensing application in the terahertz (THz) waveguide. The five layers octagonal shape in circular air holes of cladding region with two layers rotated-hexa shape in circular air holes of core area are proposed in this study. The mathematical analysis is achieved from the technique of perfectly matched layers (PML) boundary condition with a finite element method (FEM) at the terahertz (THz) wave propagation. After the simulation process, the designed O-PCF sensor performs the extreme relative sensitivity at 77.14%, 78.06% and 76.11% at 1 THz for three chemicals such as Ethanol (n = 1.354), Benzene (n = 1.366) and Water (n = 1.330). Alternatively, the low confinement losses are 2.26 × 10−03 dB/m, 3.02 × 10−06 dB/m and 2.72 × 10−02 dB/m for similar three chemicals at 1 THz. The effective area, effective mode index and total power fraction are also concisely explained here. Furthermore, we hope that the suggested excellent designed of octagonal photonic crystal fiber (O-PCF) can be utilized particularly for chemical sensing in material study, industrial areas, nano-optics, biomedical and others communication areas in THz technology.

True-Time Delay Line Based on Dispersion-Flattened 19-Core Photonic Crystal Fiber

A novel design of a tunable True-Time delay line (TTDL) based on a multicore photonic crystal fiber (PCF) is proposed. It enables simultaneous transport and processing of microwave photonic signals over a broad radiofrequency processing range. Independent group delay behavior in 19 different cores characterized by a constant differential group delay between cores provides TTDL operation on 19 signal samples. The 19-core PCF structure allows tailoring the chromatic dispersion range between 1.5 and 31.2 ps/nm·km, which translates into a very broad microwave signal processing range from a few up to tens of GHz. A near-zero dispersion slope reduces the time delay errors in the TTDL's operation to less than 5% in a 40-nm optical wavelength range, thus ensuring its satisfactory performance. Its performance as a TTDL is evaluated in terms of higher-order dispersion as well as other degradation effects such as crosstalk and nonlinear fiber response. A high index contrast between core and cladding, between 0.3 to 1.5%, enables low intercore crosstalk and confinement losses as well as greater robustness against fiber bends and twists. Fabrication of this type of MCF might be possible although it will prove challenging. This work advances the state-of-the-art of a TTDL based on SDM technology by increasing the number of samples and microwave processing range.

Design of Highly Sensitive Photonic Crystal Fiber for Sensing Harmful Chemicals

Highly sensitive Photonic Crystal Fiber (PCF) has been designed and investigated for sensing the most harmful chemicals that exist in the world. The proposed structure of PCF consists of a solid circular core in which the samples of the chemicals are to be filled, surrounded by a hexagonal air-hole ring. The outermost cladding region comprises circular air-holes arranged in a helical (spiral) manner. Moreover, the sensitivity ratio of the liquid samples is investigated with respect to the wavelength. Sensitivity is monitored by checking for different wavelengths that range from 0.4μm to 1.85μm. With this proposed structure, the relative sensitivity of the chemicals such as paraffin liquid (n=1.48), pyridine (n=1.51), and bromobenzene (n=1.56) are found to be 78.49%, 82.99%, and 89.34% respectively. The proposed PCF structure is used to detect chemicals and any liquids due to its high sensitivity, large effective mode area, and low confinement loss.

Novel spider web photonic crystal fiber for robust mode transmission applications with supporting orbital angular momentum transmission property

In this article, a novel spider web shaped circular photonic crystal fiber (PCF) is proposed and analyzed. It can support more orbital angular momentum (OAM) modes up to 26. This PCF also operates at 1000 nm bandwidth ranging from 800 to 1800 nm. The proposed PCF provides a design strategy for better OAM quality by using the finite element method (FEM). It also includes seven OAM parameters with a better requirement of PCF. In addition, relatively lower confinement loss (less than $$10^{ - 8}$$ dB/m) is obtained for maximum eigenmodes. The most of OAM modes are shown smooth dispersion profile. Besides, the nonlinear coefficient is comparatively low, maximum modes are shown nonlinear coefficient around 2 to 3 W−1 km−1 at 1.55 μm. This novel structure is a strong candidate for robust, secure, high speed, and high-capacity transmission. It can be also used in mode division multiplexing, long haul communication and sensing.

Gas sensing with Hollow-Core Photonic Crystal Fibres: A comparative study of mode analysis and gas flow performance

The design flexibility of Hollow-Core Photonic Crystal Fibres (HC-PCFs) is a significant feature that allows the fibres to achieve excellent optical properties. Changes in the design parameters of HC-PCFs used for gas sensing can affect their optical and gas flow properties. The aim of this paper is to investigate the performance of three HC-PCFs with different geometries (HC-800-02, HC-1550-02, HC-2000-01) in terms of their optical mode and gas flow performance. The numerical model for the optical mode analysis is presented. The optical performance of three HC-PCFs is examined at different wavelengths in terms of their effective refractive index, mode field diameter, confinement loss and relative sensitivity. The numerical model for gas flow simulations based on Navier-Stokes and gas diffusion equations is also presented. This model is used to examine the gas velocity, relative average concentration, volumetric flow rate and gas filling time for three different HC-PCFs and three different gases. A series of gas sensing experiments based on pulsed continuous-wave modulated photothermal spectroscopy is conducted to validate the gas flow numerical model. A comparison between the three HC-PCFs indicates that the HC-PCF with the smallest size is associated with the lowest confinement loss but the highest gas filling time.

Large Mode Area Photonic Crystal Fiber with Low Dispersion and Confinement Loss for Terahertz Wave Guiding

A photonic crystal fiber (PCF) made of the cyclic-olefin copolymer (COC) with low dispersion and confinement loss, large-mode-area, and single-mode transmission for terahertz wave guiding is described. The characteristics of the PCF in the terahertz range are simulated and analyzed by the full-vector finite element method (FEM). The effects of the structural parameters on the performance of the terahertz PCF are also investigated. The effective mode field area of the PCF is as large as 1.22084 × 107 μm2 at a wavelength of 1,000 μm and a flat dispersion of 0.07669 ± 0.33258 ps/nm/km is obtained. A much lower confinement loss of 6.0253 × 10-16 dB/m is achieved. The single mode transmission over the entire terahertz wave band is described.

Low dispersion and confinement loss photonic crystal fiber for orbital angular momentum mode transmission

In this paper, we design a novel type of photonic crystal fiber (PCF) with a kind of typical micro-structure in its innermost cladding area, which can totally transmit 26 orbital angular momentum modes (OAMs). Over a bandwidth of 300 nm from 1.5 to 1.8 μm, this new type PCF shows a great improvement in dispersion property when it is compared with the total internal reflection PCF for reference. Moreover, other mode properties are also calculated and listed in curves, including effective indices, confinement loss and nonlinear coefficient. And basing on the test results, we further ameliorate the micro-structure and cladding of previous PCF structure and propose two effective ways to reduce the dispersion and confinement loss respectively. One is to insert typical type of micro-structure; the other is to change the arrangement and size of air holes in the cladding area. We finally propose an optimized structure which can support 30 OAM modes with the application of the two ways. Results show the optimized structure performs very well and achieves great progress in terms of dispersion and confinement loss.

Slope matched highly birefringent hybrid dispersion compensating fiber over telecommunication bands with low confinement loss

This article reveals a best possible design for hybrid dispersion compensating fiber with high birefringence established on modified broadband compensating structure through S, C and L telecommunication bands. The simulation outcome exhibits relatively higher birefringence of 3.76 × 10−2 at wavelength of 1550 nm. The suggested fiber also has dispersion compensation characteristics in an inclusive series of wavelengths which covers 1400–1625 nm. The reported design can achieve dispersion quantity of − 606 ps/(nm·km) at 1550 nm effective wavelength. The reported fiber design matches the relative dispersion slope 0.003694 nm−1 similar to single-mode fiber at 1550 nm operating wavelength. This fiber demonstrates negatively flattened effective dispersion of − 2.703 ± 0.734 ps/(nm·km) within 180 nm flat band ranging from 1460 to 1640 nm wavelength. It is also convenient to optical high bit rate communication systems. The low confinement loss is found 3.756 × 10−10 dB/m at the operating wavelength. This design also achieves highly nonlinear coefficient of 50.34 W−1 km−1. In some cases, it can also be used in sensing applications.

Proposal for a symmetrical petal core terahertz waveguide for terahertz wave guidance

Countering the terahertz wave applications ‘inefficient transmission’ calls for rapid development in terahertz waveguides that could simultaneously minimize confinement loss, chromatic dispersion and maximize the fraction of power. Here, a new kind of symmetrical petal hollow core terahertz waveguide based on cyclic olefin homopolymer is proposed to achieve low confinement loss, low chromatic dispersion and a high fraction of power. In this designed waveguide, a symmetrical petal-shaped air hole is treated as the core and circular air holes arranged as sunflower-type are inserted in the cladding. The guiding characteristics of the designed waveguide are simulated and analyzed based on the finite element method with perfectly matched layer boundary condition. Based on the optimum structure parameters, it exhibits a minimum confinement loss of 0.0089 dB cm−1 at 2.58 THz and a < 0.07 dB cm−1 bandwidth spanning across 2.51–2.71 THz. Furthermore, in the same frequency region, the high core power fraction is above 93%, and the group velocity dispersion values are lower than 0.6 ps/THz/cm.

Two Sides Rhombus Shaped Cladding Hexagonal PCF with Low Confinement Loss and Negative Dispersion

A novel design of solid core photonic crystal fiber (PCF) has been proposed with seven rings rhombus inside eight rings hexagonal structure. Waveguide properties have been numerically investigated by utilizing the full vectorial finite element method (FEM). Here the paper elaborates PCF characteristic like confinement loss, dispersion properties, normalize frequency, mode field diameter, effective area, and nonlinear coefficient with asymmetric cladding designed and investigated. Silica is used as background material. The calculated value shows the ultra-low confinement loss in 1.1 µm to 1.7 µm, low negative dispersion -400ps/km-nm achieved in solid core. The high nonlinear coefficient 3.1661762 W-1km-1 and 3.141089 W-1km-1 at 1.55 µm in xpolarization and y-polarization mode respectively achieved. PCF achieved low confinement loss and better mode field diameter for remote sensing application.