Ultrahigh Birefringence Research Articles

Research on ultra-high birefringence terahertz fibers with simple structures

Research on ultra-high birefringence terahertz fibers with simple structures

High birefringence low loss nearly zero flat dispersion similar to slotted core photonic crystal fibers

Abstract Studying high-performance photonic crystal fibers (PCF) is of significant scientific importance for terahertz (THz) waveguide systems. This study introduces a novel PCF design with a core composed of the smallest sub-wavelength units resembling a slotted structure, aiming to achieve high birefringence and low loss. The optical properties of the proposed PCF are analyzed through simulations, yielding impressive results. The PCF exhibits an ultra-high birefringence of 0.07848, a minimum limiting loss of 10−17 dB/cm, and an effective material loss as low as 0.04251 cm−1. Moreover, it demonstrates near-zero flat dispersion of −0.012 ± 0.074 ps/THz/cm over a broad frequency range of 1.2–2.2 THz. This fiber stands out by not only providing high birefringence but also by striking an optimal balance among birefringence, transmission loss, and dispersion for THz waveguides. The implications of this work are profound for the development of THz communication systems, THz polarization-maintaining transmission, and sensing applications. Furthermore, it established an important benchmark for the design of THz-PCFs that prioritize high birefringence, low loss, and near-zero flat dispersion, offering an essential reference for future research and development in this field.

Research on Simultaneous Measurement of Magnetic Field and Temperature Based on Petaloid Photonic Crystal Fiber Sensor.

In this paper, we propose and design a magnetic field and temperature sensor using a novel petaloid photonic crystal fiber filled with magnetic fluid. The PCF achieves a high birefringence of more than 1.43 × 10-2 at the wavelength of 1550 nm via the design of material parameters, air hole shape and the distribution of the photonic crystal fiber. Further, in order to significantly improve the sensitivity of the sensor, the magnetic-fluid-sensitive material is injected into the pores of the designed photonic crystal fiber. Finally, the sensor adopts a Mach-Zehnder interferometer structure combined with the ultra-high birefringence of the proposed petaloid photonic crystal fiber. Magnetic field and temperature can be simultaneously measured via observing the spectral response of the x-polarization state and y-polarization state. As indicated via simulation analysis, the sensor can realize sensitivities to magnetic fields and temperatures at -1.943 nm/mT and 0.0686 nm/°C in the x-polarization state and -1.421 nm/mT and 0.0914 nm/°C in the y-polarization state. The sensor can realize the measurement of multiple parameters including temperature and magnetic intensity and has the advantage of high sensitivity.

Adaptive Fiber Ring Laser Based on Tapered Polarization Maintaining Fiber in Sagnac Loop for Temperature and Salinity Sensing

An optical fiber ring laser (FRL) cavity-based sensitive temperature and salinity sensor is proposed and experimentally demonstrated. The sensor consists of a Sagnac loop with a waist of 15 µm and a total length of 30 cm made of tapered polarization-maintaining fiber (PMF). Sagnac loop dual parameter sensing was theoretically modeled and presented. The salinity sensitivity of 0.173 nm/‰ was made possible by the efficient interaction between the tapered PMF cladding mode and the external refractive index. In addition, temperature sensitivity of 0.306 nm/°C was achieved through ultrahigh birefringence of PMF. Apart from that, the previous sensing system used a broadband light source (BBS) as the input light, resulting in a wide bandwidth and a poor signal-to-noise ratio (SNR). The Sagnac loop integrated into the FRL system can achieve a high SNR of approximately 50 dB and a narrow bandwidth of 0.15 nm while serving as the filter and sensor head. Additionally, the developed sensor has the advantages of simple design, low cost, and easy fabrication. It can also extend sensing distance indefinitely within a given range, which is anticipated to have positive effects on the testing of marine environments in laboratories.

Ultra-high birefringence mid-infrared Ge20Sb15Se65 chalcogenide glass photonic crystal fiber with low confinement loss

This study introduces a Ge20Sb15Se65 chalcogenide-glass-based photonic crystal fiber (PCF) with high birefringence and nonlinearity and ultra-low confinement loss, in which two elliptical air holes are added in the core. The propagation properties of the proposed PCF are investigated in mid-infrared range (3.0–5.0 μm) using the finite element method (FEM). Simulation results indicate that optimizing structural parameters can increase the birefringence and nonlinear coefficient to a maximum of 3.16 × 10−1 and 5937 W−1km−1 (in y-polarization mode), respectively, a significantly low confinement loss reach 10−14 dB m−1 at 3.0 μm wavelength, there can obtain one zero dispersion wavelength in the study band, and the designed structure can be fabricated using available technology. The designed PCF will have promising application in mid-infrared fiber fields, optical communication, super-continuum generation, precision, and nonlinear optics.

Ultra-high birefringence with tuneable double zero chromatic dispersion-PCF: a theoretical analysis

This work presents photonic crystal fibres made up of four hexagonal shape of four rings. Four structures have been designed and configured. The structures show improvement in optical properties consecutively to achieve the optimum configuration. The full vectorial finite-element method is adopted for this work. COMSOL Multiphysics is used for the simulation. The results show a birefringence of 1.308 × 10−2 at 1.55 µm and tuneable double zero dispersion at wavelengths of 0.99 µm and 1.8 µm for x-polarisation mode. Also, the chromatic dispersion of − 24.062 ps/km nm and nonlinear coefficient of 30.32 W−1 km−1 are obtained at a telecommunication wavelength of 1.55 µm. The proposed photonic crystal fibre can be beneficial in nonlinear and supercontinuum applications since photonic crystal fibres of double zero dispersion demonstrate higher power spectral densities than single zero dispersion.

A nonlinear ZBLAN-based photonic crystal fiber with ultra-high birefringence and flattened dispersion in short-wavelength infrared region

In this paper, a high nonlinear ZBLAN-based photonic crystal fiber (PCF) with ultra-high birefringence and flattened dispersion is numerically proposed in short-wavelength infrared region based on finite element method. Eight elliptical-hole arrays are arranged surrounding the fiber core to separate x-polarized and y-polarized fundamental modes. The birefringence can reach to an excellent level of 4.46 × 10−2 at wavelength 2.5 µm and interestingly shows a hopping phenomenon as the ellipticity increases from 2.2 to 3.1. In addition, the design also exhibits a single-mode propagation, short beat length (< 0.12 µm), high nonlinear coefficient 131 W−1·km−1, low confinement loss 10−9 dB/m and flattened dispersion with a maximum fluctuation 50 ps·km−1nm−1 in wavelength range from 1.5 µm to 2.5 µm. The effect of the structure parameters (air hole diameter, lattice constant and ellipticity of elliptical holes) on the optical properties is symmetrically investigated. This ZBLAN-based PCF has great potential in the nonlinear applications of fiber laser and supercontinuum generation in infrared region.

GaP-filled PCF with ultra-high birefringence and nonlinearity for distinctive optical applications

A gallium phosphide (GaP) based photonic crystal fiber (PCF) with hexagonal air hole arrangements is introduced in this study that reveals high birefringence (Br) and nonlinear coefficient (NLC). Numerous optical properties, such as birefringence, nonlinearity, dispersion, confinement loss, effective area, core power fraction, etc. are studied by finetuning the geometrical variables, applying the finite element method (FEM). The numerical analyses demonstrate that an ultra-high Br of 59.1 × 10−2 and NLC of 2.37 × 105 𝑊−1𝐾𝑚−1 with a large negative dispersion of ―3875.21 ps. nm―1 . km−1 can be accomplished at the wavelength of 1.55 𝜇𝑚. Consequently, the developed PCF can be applied in a plethora of intriguing applications, including supercontinuum generation, telecommunications, etc.

GaAs-filled elliptical core-based hexagonal PCF with excellent optical properties for nonlinear optical applications

This manuscript comes up with a unique GaAs-filled elliptical core-based hexagonal cladding PCF that manifests ultra-high birefringence (Br) and non-linear coefficient (NLC). The distinct optical characteristics of the PCF are thoroughly simulated and analyzed by the finite element method (FEM) through the commonly available COMSOL Multiphysics software. The simulated findings confirm that using the high refractive index (RI) advantages of GaAs at the effective wavelength of 1.55 μ m , a high Br of 0.92 , as well as an ultra-high NLC of 2.06 × 10 6 W − 1 K m − 1 and zero-dispersion can be obtained. Besides, several primary optical properties, namely numerical aperture (NA), confinement loss (CL), power fraction (PF), dispersion, etc. are also discussed and investigated in depth in the propounded article. The zero-dispersion characteristic, as well as the high Br and ultra-high NLC of the advanced PCF model, make it a worthy candidate for extensive purposes, including biochemical detection, high nonlinear applications, supercontinuum generation, optical communication and other sensing applications.

A Nonlinear Zblan-Based Photonic Crystal Fiber with Ultra-High Birefringent and Flattened Dispersion in Short-Wavelength Infrared Region

A Nonlinear Zblan-Based Photonic Crystal Fiber with Ultra-High Birefringent and Flattened Dispersion in Short-Wavelength Infrared Region

D-shape photonic crystal fiber for optical coherence tomography: design and analysis

A simple D-shaped photonic crystal fiber (D-PCF) with silicon-nano-crystal enrichment is proposed, with substantial nonlinearity, ultrahigh birefringence, and a higher degree of transverse resolution. To scrutinize the optical properties of the suggested D-PCF, the full vector finite-element method has been employed with an anisotropic perfect matched layer added around the designed model as a boundary condition. An elliptical air hole is being used as the core region of this simple structure, and thus it can achieve the most desirable property birefringence in the order of 10 − 2. Tight mode confinement inside the core region benefits the large Kerr nonlinearity (γ) of 2.8 × 105 and 2.3 × 105 W − 1 km − 1 for X and Y polarization modes, respectively, at a wavelength of λ = 1.55 μm. Meanwhile, the numerical aperture is extraordinarily high, exceeding 0.60, with many applications in optical coherence tomography and other related fields. Due to the simple design and low air filling fraction, the D-PCF is feasible for practical realizations in many sectors.

Design of ultrahigh birefringent stress-induced polarization-maintaining fiber with hole-assistance

We present a stress-induced ultrahigh-birefringence fine-diameter polarization-maintaining fiber (PMF). The proposed PMF is composed of an elliptical-core, with four elliptical side-holes distributed around it, and two symmetrical circular/bow-tie stress-applying parts (SAPs) creating a fiber with both geometric and stress birefringence. The influence of the air-hole dimensions and positions on the properties of the proposed PMF, including modal birefringence, effective mode area, and nonlinearity, is comprehensively investigated via numerical simulations. This characterization reveals that this novel design with appropriate parameters for the air-holes is capable of ultrahigh birefringence of 1.27 × 10−3 in Panda-type PMFs and 1.28 × 10−3 in Bow-Tie PMFs at a wavelength of 1550 nm. This result shows a three-fold increase relative to the birefringence of a conventional Panda-type PMF. The effective mode area is ideal for sensing applications and there is a significant improvement in the nonlinearity. Remarkably, the fiber still exhibits excellent reflection spectra characteristics after being inscribed into the grating. The fabrication process of the novel PMF is briefly introduced. The geometric dimensions of the side-holes in the proposed PMF are shown to be deviation-tolerant within the existing fiber manufacturing facility restrictions, and thus are promising for practical fabrication. In summary, the proposed PMF with improved polarization-maintaining ability is a promising candidate for wide use in high-precision optical fiber sensors and fiber communication systems, with the specifications of the fine-diameter PMF conforming to the trend of miniaturization in current fiber optic sensors.

Ultra-high birefringence elliptical cladding polarization-maintaining fiber with superimposed geometric birefringence

In this paper, an ultra-high birefringence thin-diameter elliptical cladding polarization-maintaining fiber (PMF) with an elliptical core is designed based on employing both geometric and stress birefringence. The influence of core and stress rods parameters on the modal birefringence of the fiber under different superposition methods are analyzed by the finite element method. The results show that a higher birefringence value can be obtained when the fiber core and stress rods are superposed vertically, and the maximum birefringence value is 1.24×10−3, which is twice that of Panda-type PMF. Besides, the mode field of the fiber and the fabrication method are also studied. In sum, the designed fiber has excellent polarization-maintaining performance and looks promising for application in fiber optic sensors.

An ultra-high birefringent and nonlinear decahedron photonic crystal fiber employing molybdenum disulphide (MoS2): A numerical analysis

A novel Decahedron photonic crystal fiber (DHn-PCF) is proposed. To sustain high birefringence and nonlinearity, the central elliptical core is filled with a highly nonlinear 2D material molybdenum disulphide (MoS2). The significant performance parameters of the proposed DHn-PCF like birefringence, nonlinearity, confinement loss, and core power fraction has been investigated with change in its structural parameters. Simulation results confirmed an exceptionally high birefringence and nonlinearity of 0.632 and 9.68 × 105 W−1 Km−1 with the outstanding core power fraction of 98.6% for the well-known communication window at 1.55μm. Besides, the effective material loss (EML) and confinement loss (CL) are also found very low as 0.0302cm-1 and 8.7×10-10dB/mfor the same communication window. Therefore, with all these excellent outcomes, the proposed DHn-PCF proves itself a potential candidate for polarization maintenance, residual polarization compensation, dispersion compensator, bio-medical imaging, supercontinuum and solitons generation, high bit data rate telecommunication and sensing application.

Highly Birefringent, Low Flattened Dispersion Photonic Crystal Fiber in the Terahertz Region

High-performance photonic crystal fiber (PCF) has an important impact on the development of the full potential of complex terahertz systems. A new kind of PCF with D-shaped air holes in core region was proposed for terahertz (THz) region. The numerical simulation results showed that the proposed PCF has a flat dispersion of 0.09 ± 0.28 ps/THz/cm at 0.8-1.2 THz. At 1 THz, an ultra-high birefringence of 0.0595, a low effective material loss (EML) of 0.0557 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , and dispersion that can be considered zero were obtained. In addition, other characteristics of the proposed PCF were strictly analyzed, such as confinement loss, bending loss, and effective mode area. The PCF is expected to be used for short distance propagation of terahertz, polarization maintaining and sensing applications of terahertz waves.

Design of a photonic crystal fiber with low confinement loss and high birefringence

A photonic crystal fiber (PCF) for long distance communication was proposed in this paper. The circular and elliptical air holes distribute in the cladding, and there are two small elliptical air holes around the core in cross section of the PCF. The characteristics of the PCF were analyzed by using the finite element method (FEM) sys-tematically. The results show that the PCF offers an ultrahigh birefringence of 3.51×10-2 and the confinement loss as low as 1.5×10-9 dB/m with the optimal structure at the wavelength of 1550 nm. Compared with the existing photonic crystal fibers with elliptical air holes, the birefringence has a large increase, and the confinement loss reduces by 5 orders of magnitude. Additionally, we also analyzed the relationship between the dispersion of the PCF and the wavelength, and obtained the Brillouin gain spectrum characteristics. In general, the PCF can be used in long distance communication system.

A highly birefringent bend-insensitive porous core PCF for endlessly single-mode operation in THz regime: an analysis with core porosity

We present an endlessly single-mode, bend-insensitive and highly birefringent photonic crystal fibre (PCF) for efficient wave transmission in the terahertz (THz) spectrum. To facilitate flat dispersion and high birefringence, a diamond-shaped porous core is introduced inside the Zeonex (background material)-based hexagonal porous cladding. Moreover, the dense geometrical arrangement of the regular hexagonal lattice in the cladding region holds maximum usable optical power inside the porous core. The major geometrical parameter of the proposed PCF such as core porosity has been optimized to improve the optical guiding parameters. The numerically investigated outcomes have shown an ultrahigh birefringence and numerical aperture of 0.0888 and 0.57, respectively. Apart from this, very low bending and material losses of $$3.01 \times 10^{ - 20}$$ cm−1 and 0.01451 cm−1 with flattened dispersion variation of ± 0.2463 ps/THz/cm have been achieved over the broad THz band (i.e. 0.8–1.3 THz). Additionally, our proposed PCF sustains endlessly single-mode operation with a very high core power fraction of 75.28%. With all these promising results, the proposed PCF would be a potential candidate for polarization preserving as well as for efficient broadband transmission applications in the THz regime.

A Novel Ultra-high Birefringent Photonic Crystal Fiber for Nonlinear Applications

In this paper, a novel polarization-maintaining highly birefringent photonic crystal fiber (PMHB-PCF) has been investigated by using finite element method (FEM). Initially, the numerical analysis is carried out to ascertain its PMHB characteristics by using two different novel PCF structures (hexagonal-elliptical PCF and elliptical-elliptical PCF) and their performance characteristics are measured. By inducing the asymmetries in the fiber structure, the beat length of the fiber and their modal birefringence have been optimized. In proposed designs hexagonal-elliptical (cladding layers) PCF structure provides an ultra-high birefringence of about 4.51 × 10–2 with a lower beat length of 34.37 µm. This reported fiber exposed a high nonlinear coefficient of about 61. 95 W−1 km−1 at the operating wavelength of 1.55 µm. Also, it has a normalized frequency parameter (V parameter) of about 1.373 over the optical spectrum of 1.3 to 1.6 µm; it ensures the fiber single-mode operation. Due to the high nonlinearity and birefringence, this fiber is more suitable for nonlinear applications. It confirms the phase-matching conditions for the purpose like wavelength conversion which employs four-wave mixing technique.

Numerical analysis of photonic crystal fiber of ultra-high birefringence and high nonlinearity

A numerical analysis of a hexagonal PCF structure with four circular air hole rings around the core has been presented in this paper. By utilizing a full vectorial finite element method with perfectly matched layers, propagation properties such as birefringence, chromatic dispersion and confinement losses are numericaly evaluated for the proposed PCF structure. Specifically, birefringence of 2.018 × 10–2, nonlinear coefficients of 40.682 W−1 km−1, negative chromatic dispersion of − 47.72 ps/km.nm at 1.55 µm and − 21 to − 105 ps/km.nm at the telecommunication band of C-U have been reported.

Ultra-high birefringent low loss suspended elliptical core photonic crystal fiber for terahertz applications.

This paper presents a low loss suspended core microstructured fiber with ultra-high birefringence for terahertz wave guidance. The finite element method (FEM) with a perfectly matched layer is applied to investigate different important properties including effective material loss (EML), birefringence, dispersion, confinement loss, and percentage of power flow through the core. The suspended elliptical core in the design creates asymmetry and results in an unprecedented value of birefringence. The simulated results using FEM at 1 THz show an extremely ultra-high birefringence (the highest, to the best of our knowledge) of 0.1116, a nominal EML of 0.04716cm-1, a negligible confinement loss of 2.65×10-7cm-1, a higher power fraction in the core air of 35%, and an effective modal area of 1.24×105µm. The advancement in technology makes the fabrication possible. The proposed fiber could be used satisfactorily in the terahertz regime for various polarization-preserving applications and coherent communication.