Design Of Photonic Crystal Fiber Research Articles

Design of Single Mode Photonic Crystal Fiber with Outstanding Characteristics of Confinement Loss and Chromatic Dispersion over S to L Communication Band

In this article, a novel structure of photonic crystal fiber with nearly zero ultra- flattened chromatic dispersion and ultra-low confinement loss is presented. By replacing the circular air-holes of two first rings with the elliptical air-holes, a fiber with outstanding features of chromatic dispersion and confinement loss is designed. The proposed structure is optimized for operating in a wide wavelength range covering S, C, and L communications bands. Finite Difference Frequency Domain (FDFD) solver is applied to analyze the proposed fiber components. The designed fiber exhibits a chromatic dispersion of -0.12 ps/nm/km at 1.55 µm along with a slope of 0.002 ps/nm 2 /km. Also, the other remarkable feature of this fiber is ultra-low confinement loss in order of 10 -5 dB/km around λ = 1.55 µm.

High power broadband mid-infrared supercontinuum fiber laser using a novel chalcogenide AsSe2 photonic crystal fiber

A high power supercontinuum (SC) based on a new type of chalcogenide AsSe2 material for broadband mid-infrared light source is numerically reported. Ultra-broadband coherent mid-IR SC generation with more than 3 octave-spanning from 1.7 to 14μm in a novel design of chalcogenide AsSe2 photonic crystal fiber (PCF) is demonstrated. To the best of our knowledge and aiming to properly model the nonlinear propagation, an accurate fit of the Raman response function and the corresponding Raman gain of the novel AsSe2 chalcogenide glass are proposed numerically for the first time. The obtained SC is generated by pumping at 3.9μm in the anomalous dispersion regime in only 8mm long fiber. Our study shows that the initially generated SC from 150fs pulse duration with 8.8kW peak power exhibits high power proportion of more than 80% for wavelengths beyond 3μm which is very promising for designing high power SC fiber laser sources in the mid-IR atmospheric windows and the molecular fingerprint region.

Analysis and Design of Single-Mode As2Se3-Chalcogenide Photonic Crystal Fiber for Generation of Slow Light With Tunable Features

Theoretical investigation leading to design of a single-mode As2Se3-chalcogenide photonic crystal fiber is reported for generation of a tunable slow light. Maximum allowable pump power for undistorted output pulse, Brillouin gain, and time-delay experienced by the pulse propagating in designed photonic crystal fibers are simulated. We have found that Brillouin gain upto ∼88 dB/m and time delay up to ∼137 ns can be obtained from 1-m-long photonic crystal fiber pumped with 100 mW. Simulated results indicate that the time delay experienced by the pulse can be tuned with the pump power and structural parameters of As2Se3 -chalcogenide photonic crystal fiber.

Design of triangular core LMA-PCF with low-bending loss and low non-linearity for laser application

In this paper we characterize the design of a simple large-mode area photonic crystal fiber (LMA-PCF) with low bending loss and low non-linearity. The finite element method (FEM) with perfectly matched boundary layer (PML) is used to investigate the guiding properties. According to simulation the characterized four ring fluorine doped triangular core LMA-PCF achieves 1500µm2 effective mode area with a low bending loss of10-5dB/km at the wavelength of 1.064µm and at a bending radius of 40cm which is suitable for high power fiber laser.

Metaheuristic algorithms for dispersion optimization of photonic crystal fibers

In this paper, recent metaheuristic algorithms such as central force optimization (CFO) and particle swarm optimization (PSO) have been used for efficient calculation and optimization of the dispersion properties of photonic crystal fibers (PCFs), in an easy, efficient, and simple way. The suggested approach depends on the use of full vectorial finite difference method along with the optimization techniques for PCF dispersion optimization. The design of ultra-flattened zero dispersion PCF over a wide band of wavelengths from 1.25 to 1.6 µm is carried out in order to introduce the advantages of using these algorithms in conjunction with the numerical methods. Additionally, the CFO and PSO algorithms have a strong potential to be intriguing tools for the design and optimization of different photonic devices. Further, these algorithms prove to be powerful techniques for solving the inverse problems.

Investigation of temperature sensing characteristics in selectively infiltrated photonic crystal fiber.

In this paper, we investigate and experimentally demonstrate the influences of distance between the silica core and the glycerin core of a selectively glycerin-infiltrated photonic crystal fiber (PCF) on the mode characteristics, as well as the temperature sensitivity. By comparing the simulation and experiment results of three single-void glycerin-infiltrated PCFs with the glycerin core being one period, two periods and three periods away from the silica core respectively, it reveals that the smaller distance between the silica core and the glycerin core does not affect the modes indices, but increases the intensities of modes in the glycerin core and thus enhances the temperature sensitivity. Consequently, the temperature sensitivity can be controlled and tuned by appropriately designing the structure parameters of glycerin-infiltrated PCF. Besides, the highest temperature sensitivity up to -3.06nm/°C is obtained in the experiment as the glycerin core is nearest to the silica core. This work provides insights into the design and optimization of the liquid-infiltrated PCF for sensing applications.

PCF Based Sensor with High Sensitivity, High Birefringence and Low Confinement Losses for Liquid Analyte Sensing Applications

In this paper, we report a design of high sensitivity Photonic Crystal Fiber (PCF) sensor with high birefringence and low confinement losses for liquid analyte sensing applications. The proposed PCF structures are designed with supplementary elliptical air holes in the core region vertically-shaped V-PCF and horizontally-shaped H-PCF. The full vectorial Finite Element Method (FEM) simulations performed to examine the sensitivity, the confinement losses, the effective refractive index and the modal birefringence features of the proposed elliptical air hole PCF structures. We show that the proposed PCF structures exhibit high relative sensitivity, high birefringence and low confinement losses simultaneously for various analytes.

Design and optimization of photonic crystal fiber with improved optical characteristics

A highly birefringent photonic crystal fiber (PCF) with large nonlinearity, low dispersion and low confinement loss is designed by introducing a solid elliptical core structure with spiral lattice of circular air holes as a cladding. The dependence of different geometrical parameters, such as pitch size, diameter of air holes and arrangement of air holes are investigated. By optimizing the available parameters, the designed elliptical–spiral PCF offers high birefringence up to 0.005264, high nonlinearity up to 8683.59[Formula: see text]W[Formula: see text][Formula: see text]km[Formula: see text], low chromatic dispersion of [Formula: see text][Formula: see text]ps/nm/km, and low confinement loss of 0.00305[Formula: see text]dB/km within a wide wavelength range of 1000–2000[Formula: see text]nm.

A design for single-polarization single-mode photonic crystal fiber with rectangular lattice

A design for single-polarization single-mode photonic crystal fiber with rectangular lattice is proposed in this paper. The proposed fiber is studied by the full vector finite element method with perfectly matched layers. The single-polarization single-mode operation region of the fiber is achieved in a certain wavelength range with low confinement loss include the wavelength of 1.55μm. The loss of one polarization is 0.124dB/km at the wavelength of 1.55μm and the confinement loss of the other one polarization is very high which can not ensure the transmission in the fiber. The single-polarization single-mode photonic crystal fiber is desirable for some polarization-sensitive applications such as high-power fiber lasers, fiber optic gyroscopes, current sensors and optical coherent communication systems.

Design and numerical analysis of microstructured-core octagonal photonic crystal fiber for sensing applications

This paper presents an octagonal photonic crystal fiber (O-PCF) for liquid sensing, in which both core and cladding are microstructured. Some propagation characteristics of proposed structure have been investigated by using the full vectorial finite element method (FEM). Confinement loss and sensitivity are examined and compared with varying number of rings, core diameter, diameter of air holes in cladding ring and pitch. It is found that sensitivity is increased for the increment pitch value, air filling ratio, core diameter, inner ring diameter as well as number of rings. At the same time confinement loss is significantly decreased. It is also found that the increment of pitch by keeping the same air filling ratio increases the sensitivity and loss. Investigating the effects of different parameters, an O-PCF structure is designed which has a significantly higher relative sensitivity and lower confinement loss.

Hybrid Square-Lattice Photonic Crystal Fiber with Broadband Single-Mode Operation, High Birefringence, and Normal Dispersion

In this study we propose a new photonic crystal fiber (PCF) design that simultaneously offers broadband single-mode operation, high birefringence, and large normal dispersion in the optical-communication wavelength regime. The waveguide is based on a hybrid square-lattice PCF (HS-PCF) that has circular air holes of two different diameters alternating in the cladding, plus a pure silica defect at the center. The optical properties of the guided modes are analyzed numerically by the finite-element method (FEM) with a perfectly matched layer as the boundary condition.

Design of all-normal dispersion photonic crystal fiber for high coherent broadband supercontinuum generation in the telecommunication window

An all-normal dispersion photonic crystal fiber with nearly zero flattened dispersion at 1550 nm is designed for generating high coherent broadband supercontinuum. It is found that an all normal dispersion photonic crystal fiber with nearly zero flattened dispersion at 1550 nm can be obtained by appropriately designing geometrical parameters and optimizing the index of the first ring of air-holes with filling different index liquid of the photonic crystal fiber. The results show that the optimized design photonic crystal fiber for pumping at 1550 nm is suitable for flat broadband and high coherent supercontinuum generation with only 4 kW input peak power in a 40 cm long of the photonic crystal fiber. It is also found the weaker the dispersion effect is, the more advantage to the high coherent broadband supercontinuum generation due to the self-phase modulation.

Design of a pentagonal photonic crystal fiber with high birefringence and large flattened negative dispersion.

Novel pentagonal photonic crystal fiber with high birefringence, large flattened negative dispersion, and high nonlinearity is proposed. The dispersion and birefringence properties of this structure are simulated and analyzed numerically based on the full vector finite element method (FEM). Numerical results indicate that the fiber obtains a large average dispersion of -611.9 ps/nm/km over 1,460-1,625nm and -474 ps/nm/km over 1425-1675nm wavelength bands for two kinds of optimized designs, respectively. In addition, the proposed PCF shows a high birefringence of 1.67×10-2 and 1.75×10-2 at the operating wavelength of 1550nm. Moreover, the influence of the possible variation in the parameters during the fabrication process on the dispersion and birefringence properties is studied. The proposed PCF would have important applications in polarization maintaining transmission systems, residual dispersion compensation, supercontinuum generation, and the design of widely tunable wavelength converters based on four-wave mixing.

Design of a circular photonic crystal fiber with flattened chromatic dispersion using a defected core and selectively reduced air holes: Application to supercontinuum generation at 1.55 μm

In this paper, we present and numerically investigate a new and simple design of Circular Lattice Photonic Crystal Fiber (CL-PCF) with near zero ultra-flattened chromatic dispersion. The near zero dispersion is obtained by introducing a defect into the solid core and the dispersion flatness is achieved by appropriately reducing the diameter of the core-neighboring air holes ring. Simulations are performed by using the finite-difference frequency-domain (FDFD) method combined with the perfectly matched layer (PML) boundary condition. Results show that an ultra-flattened chromatic dispersion as small as ±0.66ps/nmkm is obtained over a broad band of 400nm with high nonlinearity and ultra-low confinement loss. Furthermore, the supercontinuum (SC) generation over a short length of the proposed CL-PCF is numerically investigated. Results indicate that flat SC spectrum with a Full Width at Half Maximum (FWHM) of 600nm is achieved with 25cm of fiber length.

Design of photonic crystal fiber with large negative dispersion and high nonlinearity

A modified hexagonal index guiding photonic crystal fiber made of pure silica with high nonlinearity and large negative dispersion is proposed and properties, including the nonlinear coefficient and dispersion, are numerically analyzed using the multipole method. Numerical results show that a nonlinear coefficient of 37.1W−1km−1 at 1.55μm and large negative dispersion of −104, −103 and −102psnm−1km−1 in O, E, S and L communication wavebands are achieved simultaneously. Moreover, impacts of the hole spacing and hole size on the nonlinear coefficient and dispersion are also investigated in detail.

Design of small core tellurite photonic crystal fiber for slow-light-based application using stimulated Brillouin scattering

Stimulated Brillouin scattering (SBS) performances of small core tellurite photonic crystal fibers (PCF) are rigorously studied. We propose a design of tellurite PCF that is used for slow-light-based applications. We developed a two-dimensional finite element mode solver to numerically study the acoustic and optical properties of complex refractive index profiles including tellurite PCF. Our results include the calculation of Brillouin gain spectrum, Brillouin gain coefficient (gB) and Brillouin frequency shift by taking into account the contribution of the higher-order acoustic modes. Several simulations were run by varying the air-filling ratio of various PCF structures to enhance the SBS. The real scanning electron microscope image of a small core of highly nonlinear tellurite fiber is considered. Optimized results show a frequency shift of 8.43 GHz and a Brillouin gain of 9.48×10−11 m/W with a time delay between 21 and 140 ns. Such fibers have drawn much interest because of their capacity for increasing and tailoring the SBS gain.

Diamond unit cell photonic crystal fiber with high birefringence and low confinement loss based on circular air holes.

We propose a novel photonic crystal fiber (PCF) design with high birefringence and low confinement loss based on a diamond unit cell. Unit cell is a degree of freedom of PCF design, and highly asymmetric diamond unit cell can deliver both high birefringence and low confinement loss. In our fiber design, each diamond unit cell consists of two different sizes of circular air holes in a conventional hexagonal lattice, which can enhance the confinement loss with increased birefringence and can overcome the previous fabrication challenges of elliptic air hole PCFs due to the all-circular air hole structure. The optimized design shows high birefringence of 6×10(-3) over S, C, and L bands while maintaining low confinement loss.

Design and analysis of seven-core photonic crystal fiber for high-power visible supercontinuum generation

We design a seven-core photonic crystal fiber with specifically designed dispersion and group velocity profile which is optimized for high-power visible supercontinuum (SC) generation pumped by ∼1-μm pulsed lasers. The fiber has both a large air-filling fraction and a large effective mode field area. Additionally, the in-phase supermode of this fiber exhibits an even field distribution after mode modification. The simulation results suggest that it has a great potential to generate a high-power SC extending to 400 nm, which is highly desirable in biological applications.

Design and analysis of equiangular spiral photonic crystal fiber for mid-infrared supercontinuum generation

A design of equiangular spiral photonic crystal fiber (PCF) in As2Se3 chalcogenide glass is reported for mid-infrared supercontinuum generation. Supercontinuum covering the 1.2–15 μm molecular fingerprint region is achieved using only 8 mm long designed PCF pumped with 50 fs laser pulses of 500 W peak power. The structural parameters have been tailored for all-normal dispersion characteristic. Proposed structure has high nonlinearity (γ = 12474 W−1 km−1) at 3.5 μm with very low and flat dispersion −2.9 [ps/(nm × km)]. Supercontinuum with such broadening and high coherence degree is applicable for mid-infrared spectroscopy, gas sensing, early cancer diagnostics and free space communication.

Analysis of ultra-high birefringent fully-anisotropic photonic crystal fiber

Highly birefringent photonic crystal fiber (PCF) is proposed and analyzed using full vectorial finite element method. The reported design has a central large core filled with nematic liquid crystal (NLC) which provides tunability with the external electric field and temperature. In addition, the full permittivity tensor of the NLC material is taken into account when we study the modal properties of the proposed PCF. The effects of the geometrical parameters, rotation angle of the director of the NLC, and temperature on the modal properties of the reported design are investigated. The suggested design offers high birefringence of 0.191 at the operating wavelength of 1.55 lm with NLC diameter of 3.4 lm with low losses of the two polarized modes. As the NLC diameter decreases to 1.0 lm, high birefringence of 0.08 is obtained with single mode NLC PCF design, which is significantly large birefringence to maintain polarization state.