Effective Material Loss Research Articles

Design and simulation of rotated hexagonal porous core photonic crystal fibre with improved effective material loss and dispersion properties

<p><span>A thorough modal characterization, centred on the full vectorial finite element method (FEM) has been used to model and numerically investigate a porous core photonic crystal fibre (PC-PCF), which may potentially be integrated into Terahertz (10<sup>12</sup> Hz) compact systems. The proposed fibre consists of a rotated hexagonal core surrounded by a conventional hexagonal cladding. It has been shown that effective material loss (EML), core power fraction and dispersion profile are 0.019 cm<sup>-1</sup>, 51.7% and 0.5 ± 0.04 ps/THz/cm within 1 THz bandwidth, respectively. Based on simulated results and noncomplex design, it is envisaged that the proposed fibre can be realised for industrial THz applications. </span></p>

Negative curvature hollow-core anti-resonant fiber for terahertz sensing.

Hollow-core fibers are advantageous for chemical sensing as they facilitate liquid infiltration into the core over conventional porous core fiber. In addition, the requirement of less bulk material significantly decreases the effective material loss (EML). In this paper, a six circular cladding tube negative curvature hollow-core fiber (NC-HCF) is proposed for chemical sensing. Five different chemicals including chloroform, polylactic acid, CCL3, glycerin, and benzene are proposed to fill the core of the NC-HCF, and sensitivities are evaluated by full vector finite element method-based COMSOL software. Numerical results reveal that the proposed sensor exhibits very high relative sensitivity in a wide range of frequency. The fabrication of the proposed fiber is feasible by existing fabrication facilities as it contains realistic fabrication parameters. Hence, the proposed sensor can potentially be used as a chemical sensor especially in the medical, food, and industrial sectors as the five chemicals mentioned above carry great medical and food significance.

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.

A novel hollow core photonic sensor for liquid analyte detection in the terahertz spectrum: design and analysis

A novel hollow core photonic crystal fiber (PCF) is proposed for biochemical analyte detection in the terahertz regime. The prime objective of the work is to increase the sensitivity but other significant features like effective material loss, confinement loss, effective area, numerical aperture and dispersion have been thoroughly investigated over a wide bandwidth using COMSOL version 5.3. Numerical simulation shows that a maximum chemical sensitivity of 99.76% 99.44% and 99.39% can be obtained for benzene, water and methanol respectively at optimum operating conditions. The symmetry in design makes the proposed structure easily feasible to be fabricated using the existing fabrication technologies. Thus it is believed that the proposed PCF has the potential due to its higher sensitivity and lower effective material loss to uplift the standard of PCF sensors and open a new window in this field of research.

Simulation of a highly birefringent photonic crystal fiber in terahertz frequency region

We have designed a Photonic Crystal Fiber (PCF) to achieve high birefringence optical property in the terahertz (THz) frequency region. Air holes look like rectangular shape in cladding area and elliptical air hole in the center zone are considered for the proposed PCF. To identify loss characteristics of the proposed PCF, effective material loss (EML) and confinement loss also have been studied in this paper. The commercial optical properties analyzer, COMSOL Multiphysics 5.3a software has been used for numerical analysis of the designed PCF. To obtain the optimal PCF structure properties, we have varied the elliptical shaped air holes major axis length and adjacent ellipse pitch distance. Numerical analysis shows the maximum birefringence of 0.0921 and minimum confinement loss of $$1.36\, \times 10^{-4} \hbox {cm}^{-1}$$ for the proposed PCF. We hope that this highly birefringent PCF will contribute in the field of polarization filter, bio-sensing and terahertz communication devices.

Ultra-Low Material Loss Quasi Pattern Based Photonic Crystal Fiber for Long Distance THz Wave Propagation

In this study, photonic crystal fiber in quasi pattern (Q-PCF) has been proposed at the terahertz (THz) regime. In Q-PCF, the core area is designed using the two elliptical air holes for the best performance of optical communications to obtain the ultra-low effective material loss (EML). In Q-PCF, perfectly matched layer (PML) and the finite element method (FEM) have been applied to simulate the desired outcomes. The mentioned Q-PCF is optimized by shifting the core diameter, cladding air holes pitch and diameter, porosity of the model, and background materials. The numerically controlled outcomes ensure an EML of 0.01542 cm−1 with high power fraction response at 1 THz frequency. In addition, other loss profiles and operating modes have also been well described. Moreover, operating mode profile indicates single mode propagation up to 2.2 THz operating frequency. The noted outcomes ensure that the designed structure will be perfectly suitable for long distance broadband optical communication applications in THz technology.

Photonic crystal fiber based terahertz sensor for cholesterol detection in human blood and liquid foodstuffs

Low density lipoprotein (LDL) cholesterol is the leading cause of heart diseases, peripheral artery diseases, and stroke. An accurate, flexible, and efficient detection process is very urgent for identifying the cholesterol. In this context, an octagonal shaped hollow core with eight head star cladding structured photonic crystal fiber (PCF) has been proposed in this paper for cholesterol sensing in liquid analytes (human blood, cocking oil, liquid foods, etc.). The sensing performances of proposed PCF are evaluated through the COMSOL multiphysics software where the finite element method (FEM) has been used as a solver. The numerical investigation of the presented PCF structure exhibits highly sensitive characteristics for cholesterol detection in liquid samples and the proportion is 98.75% at 2.2 THz frequency. It also reveals negligible confinement loss of 3.14 × 10−20 cm−1 and low effective material loss of 0.0008 cm−1 at the same operating point. Furthermore, the commercial development feasibility of designed PCF in the existing manufacturing environment and other crucial optical properties such as effective area, dispersion, numerical aperture are also discussed in detail.

Low-loss and flat dispersion umbrella-shaped and porous-core photonic crystal fiber for terahertz applications

A novel design of a single-mode photonic crystal fiber for applications in the terahertz region is proposed and numerically analyzed. The geometrical and optical parameters of the structure are estimated by using algebraic expressions while the guidance properties are calculated by using the full-vector finite element method. The porous-core of the fiber is suspended by eight equally spaced bridges connected to an outer cladding. The obtained results show that by adjusting the structural parameters appropriately, low-loss and flat dispersion properties could be easily achieved. The numerical results show that our best configuration, with a 60% filling fraction, exhibits a low effective material loss, below 0.2 dB/cm, and a flattened dispersion behavior in the frequency range from 0.79 THz to 1.5 THz.

Development of a photonic crystal fiber for THz wave guidance and environmental pollutants detection

In recent years, photonic crystal fiber (PCF) in the THz regime has gained popularity very swiftly for wave guidance and sensing applications. The optical properties of PCF can be controlled by the fine tuning of the geometrical parameters. In this context, PCF geometry has been developed for THz wave propagation as well as for environmental pollutants sensing applications. The proposed PCF structure contains a circular manner sectored cladding and square shaped core which is inserted by four square lattices. The finite element method based COMSOL multiphysics v.5.3a software has been used to design and characterize the optical properties rigorously for both applications. Numerical outcomes of developed PCF have significantly improved in both cases because of strategic geometry selection and parameters optimization. The simulated results render high sensitivity of 90 ± 1% for all the tested analytes at optimum condition, besides, ultra-low effective material loss (EML) of 0.009 cm−1 and flattened dispersion of ±0.05 ps/THz/cm are obtained at wave guiding environment. Moreover, implementation possibilities in the existing fabrication environment, physical attributes and comparative performance analysis are also stated in this article.

Low-Loss and Dispersion-Flattened Octagonal Porous Core PCF for Terahertz Transmission Applications

In order to make the direct transmission more effective, we have intended an octagonal shape cladding design in this paper. The minimum resultant effective material loss obtained from our proposed photonic crystal fiber is 0.007 cm−1 at 0.5 THz is very effective. The proposed design gives an ultra-high birefringence of 0.06 with an effective area of about 4 × 10−6 m2, a core power fraction of 70% for 290 µm core diameter with a core porosity of 80% at 1.6 THz frequency and closely zero flattened dispersion of variation of 0.3 ± 0.1 ps/THz/cm at a wide frequency range of 0.7–2.1 THz.

Design and characterization of a circular sectored core cladding structured photonic crystal fiber with ultra-low EML and flattened dispersion in the THz regime

Abstract A circular sectored core cladding structured photonic crystal fiber (PCF) is presented in this article, where core and cladding are sectored by few number of rectangles. The air fragments of core and cladding are constructed with circular manner that can facilitate the fabrication process. To design the porous core PCF and characterize the properties for THz wave propagation, finite element method based Comsol Multiphysics software version 5.3a is employed. It is shown that the presented design yields an ultra-low effective material loss (EML) of 0.0153 cm−1 with very flat dispersion of ±0.010 (ps/THz/cm) at optimum operating frequency of 1 THz, outperforming a number of recently reported designs in the literature. Additionally, it renders comparable low confinement loss, higher core power fraction, large effective area and exhibits single-mode fiber (SMF) characteristics. Further, since only few air fragments are used in core and cladding regions in a circular fashion, the proposed PCF geometry is feasible for fabrication by using stack and draw, extrusion, 3D printing, capillary stacking, sol-gel, or any other existing fabrication technique.

Low loss and highly birefringent photonic crystal fibre for terahertz applications

A highly birefringent photonic crystal fibre, with horizontal arrangement of three elliptical air holes in the core and hexagonal arrangement of circular air holes in the cladding, has been proposed for transmission of terahertz waves. Guiding properties of the fibre have been rigorously investigated using finite element method with perfectly matched layer boundary conditions. It has been demonstrated that high birefringence of 0.08 can be achieved with low effective material loss of 0.03 cm−1 at 1.3 THz. Moreover, it has been shown that about 42 % of useful power flows through the elliptical core air holes. Near-zero flattened dispersion of 1.18 ± 0.01 ps/THz/cm is obtained for the x-polarisation mode of the fibre. Other important optical properties such as confinement, bending and total losses have also been investigated; further strengthening potential applicability of the proposed fibre for next-generation terahertz research.

Highly birefringent honeycomb cladding terahertz fiber for polarization-maintaining applications

A novel Zeonex-based photonic crystal fiber (PCF) with a honeycomb-like cladding structure and a hexagonal slotted core is proposed. The finite-element method is used to numerically analyze the guiding characteristics of the proposed fiber. The investigations are carried out by optimizing various geometrical parameters of the fiber and varying the frequency, core diameter, and core porosity. The results indicate that the designed PCF demonstrates an ultrahigh birefringence of 0.083, extremely low confinement and effective material loss of 10^{− 8} and 0.095 cm^{− 1}, respectively, and a very high core power fraction of 52.2% at an operating frequency of 1.5 THz. In addition, other guiding properties such as numerical aperture, dispersion, and effective area are also analyzed and discussed in detail. The obtained results show that the proposed PCF is extremely suitable for use in numerous low-loss, polarization-maintaining applications in the terahertz frequency range.

Ultra low loss and dispersion flattened microstructure fiber for terahertz applications

In this paper, a rectangular core hexagonal lattice porous core photonic crystal fiber (PC-PCF) is reported for effectively guiding the terahertz light signal. Finite element method with circular perfectly matched layer boundary condition is employed to find out the propagation characteristics of this proposed porous core fiber. Extensive simulation results of that microstructure fiber over wide frequency range shows that very low effective material loss of 0.035 cm-1, large effective area of 1.79×10-7 m2 and high core power fraction of 36% can be obtained simultaneously. In addition, for same designing condition nearly zero flattened dispersion of 0.46 ± 0.07 ps/THz/cm can be achieved over 600 GHz frequency band in terahertz range. Furthermore, other important parameters like single mode operation, confinement loss and bending loss are also investigated rigorously for the proposed fiber. The excellent results of this optical waveguide will pave the way to implement it in various real life terahertz applications.

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.

Highly Birefringent Slotted Core Photonic Crystal Fiber for THz Wave Propagation

We propose a novel design of a slotted core photonic crystal fiber (PCF) that offers ultra low-loss and high birefringence attribute for efficient transmission of terahertz (THz) waves. A finite element method has been used to investigate the modal characteristics of the PCF. Our design incorporates an asymmetrical structure of air holes in the core to achieve high birefringence. Moreover, in the cladding region, we have a compact geometry of air holes arranged in five hexagonal layers to obtain lower dispersion. The simulated results show that the PCF exhibits simultaneously a low effective material loss of 0.025 cm–1 and high modal birefringence of 0.0911, a flattened dispersion property of 0.65 ± 0.05 ps THz–1 cm–1 having a frequency range of 0.5 to 1.6 THz, core power fraction of 52% and very negligible confinement loss of about 1.05 × 10–13 cm–1. We believe our proposed PCF will bring about a promising improvement in high-speed broadband communications in the THz regime as well as numerous applications in the near future.

Analysis of terahertz waveguide properties of Q-PCF based on FEM scheme

A novel photonic crystal fiber in quasi pattern (Q-PCF) is designed and proposed for terahertz wave (T-wave) guidance. A cyclic olefin copolymer (COC) has been used as the bulk material of the proposed fiber. The proposed Q-PCF is introduced here for T-wave propagation, scaling from 0.8 to 2.40 THz. It is noted that, a low effective material loss (EML) of 0.038 cm−1 is obtained at working frequency f = 1 THz. It leads to a reduction in bulk absorption loss of 81% at the same working frequency. Moreover, some essential optical guiding parameters such as confinement loss, dispersion, modality, power fraction and effective mode area are also examined briefly. The fabrication of the proposed PCF is simple as it contains only air holes of circular shape. It is anticipated that the mentioned Q-PCF terahertz waveguide will provide a significant improvement over existing designs.

Porous photonic-crystal fiber with near-zero ultra-flattened dispersion and high birefringence for polarization-maintaining terahertz transmission

One unique kind of porous-core photonic crystal fiber (PCF) is proposed with elliptical air-holes in core, and round-corner hexagonal air-holes in cladding, for efficiently transmitting polarization-maintaining terahertz waves. Dispersion, birefringence, effective material loss (EML) and confinement loss are investigated by using the full-vector finite element method (FV-FEM) with anisotropic perfectly matched layers. The numerical results indicate that its near-zero ultra-flattened dispersion (-0.01±0.06 ps/THz/cm) and birefringence higher than 7.0×10−2 (highest birefringence of 7.4×10−2 at 1.2 THz) can be achieved simultaneously over almost the same frequency range of 0.75–1.6 THz, with a low EML (0.08 cm−1 at 1.2 THz) and a low confinement loss (3.2 × 10-13 cm−1 at 1.2THz). Important modal properties, such as power fraction and effective mode area, are discussed, and the tolerance in fabrication is analyzed to indicate the feasibility of the proposed terahertz waveguides with PCF structure in manufacturing.

Highly birefringent TOPAS based single mode photonic crystal fiber with ultra-low material loss for Terahertz applications

Abstract In this article, a polarization maintaining single mode photonic crystal fiber (PCF) has been suggested for Terahertz wave propagation. The proposed PCF is circular shape where five layers cladding vicinity encircles the two layers core region. The air holes of the core part are arranged in porous manner and elliptical shape. These types of air holes destroy the structural symmetry of the reported PCF and increase the level of birefringence. Optical properties of the proposed PCF are investigated by utilizing very popular pretending method that introduces as full vectorial finite element method (FEM). Several guiding mechanisms such as effective material loss (EML), birefringence, effective area, V-parameter, and power fraction are calculated by varying distinctive geometrical parameters and effects. The proposed PCF reveals ultra-low EML of 0.053 cm−1 and ultra-high birefringence of 1.34 × 10−02 at f = 1 THz. In addition, effective area and power fraction of the reported PCF are 2.36 × 10−07 m2 and 52% at the same operating frequency.

High birefringence, low loss, and flattened dispersion photonic crystal fiber for terahertz application**Project supported by the National Natural Science Foundation of China (Grant No. 11604260) and the Outstanding Youth Science Fund of Xi’an University of Science and Technology, China (Grant No. 2019YQ3-10).

A type of photonic crystal fiber based on Kagome lattice cladding and slot air holes in a rectangular core is investigated. Full vector finite element method is used to evaluate the modal and propagation properties of the designed fiber. High birefringence of 0.089 and low effective material loss of 0.055 cm−1 are obtained at 1 THz. The y-polarized fundamental mode of the designed fiber shows a flattened and near-zero dispersion of 0 ± 0.45 ps · THz−1 · cm−1 within a broad frequency range (0.5 THz–1.5 THz). Our results provide the theory basis for applications of the designed fiber in terahertz polarization maintaining systems.