Circular Lattice Photonic Crystal Fiber Research Articles

Structural dependence of transmission characteristics for photonic crystal fiber with circularly distributed air-holes

Abstract In this study, design and transmission characteristics of a special type of photonic crystal fiber (PCF) geometry namely, circular-lattice photonic crystal fiber (C-PCF) structure are presented. The cladding of the structure consists by a cylindrically symmetrical distribution of air-holes in the silica background and the core is created by omitting one air-hole at the center. The structure provides high degree of flexibility in the fiber design and hence tailorable modal properties. Structural dependence of transmission characteristics of the geometry is numerically investigated by using finite difference mode convergence algorithm. The wavelength responses of fiber parameters, such as effective refractive index, chromatic dispersion, mode-effective area, and nonlinear coefficient of the structure are systematically investigated. Besides, effective V-parameter and single-mode operation of the fiber are also evaluated and discussed. The simulation results show the possibility of large negative dispersion and dispersion flattened nature of the geometry.

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

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

Mid-infrared broadband ultraflat-top supercontinuum generation in dispersion engineered Ge-Sb-Se chalcogenide photonic crystal fiber

In this paper, we numerically demonstrate broadband, ultraflat-top and highly coherent mid-infrared Supercontinuum (SC) generation in an all-normal dispersion (ANDi) Ge15Sb15Se70 chalcogenide Circular Lattice Photonic Crystal Fiber (CL-PCF). The propagation properties of the fundamental mode are computed with the Finite Difference Method (FDM). Numerical results show that ANDi regime is obtained over the entire mid-infrared wavelength range with a cladding pitch and air holes diameter of Λ=2 μm and d=0.8 μm, respectively. Besides, the proposed CL-PCF exhibits small effective mode area and high Kerr nonlinearity up to 1.96 W−1 m−1 at 3 μm. Ultrashort pulse propagation inside the CL-PCF core is modelled by using the Generalized Non-Linear Schrodinger Equation (GNLSE). Simulation results show that by pumping at 3 μm laser pulses with a total energy of 0.6 nJ and duration of 50 fs, into 10 mm long of the CL-PCF, generates an ultrabroadband and highly coherent SC spanning the wavelength region from 1.86 μm to 5.35 μm within less than 3 dB spectral dynamics. By increasing the initial pulse energy to attain 1 nJ, the generated SC bandwidth increases too and reaches 4.53 μm in the spectral range extending from 1.67 μm to 6.2 μm at 4 dB spectral level. Moreover, the proposed CL-PCF based SC source is found promising for application in Optical Coherence Tomography (OCT) with an axial resolution of 0.87 μm, achieved when pumping 1 nJ energy and 50 fs duration optical pulses.

Gold-coated photonic crystal fiber biosensor based on surface plasmon resonance: Design and analysis

The particularly sensitive circular lattice Photonic Crystal Fiber (PCF) based Surface Plasmon Resonance (SPR) sensor is proposed to gain high sensitivity for the detection of unknown analytes. In this model, two-layer PCF based on the SPR has been designed. A plasmonic chemically inactive material gold (Au) with thickness 35 nm is used to the outside of the PCF structure which exhibits negative real permittivity. A circular perfectly match layer (PML) outside the structure is applied to evaluate the performance of the sensor. The raised design has consisted of symmetric air-hole. Three small air-holes are used in second layer and center which help us to produce more evanescent field. Using the wavelength interrogation method the proposed model shows the maximum wavelength sensitivity of 9000 nm/RIU (Refractive Index Unit) and using the amplitude interrogation method it shows the maximum amplitude sensitivity of 318 RIU−1 with maximum sensor resolution 1.11 × 10−5 in the sensing range among analyte 1.34–1.37. Here the proposed model is investigated how phase matching points are varied with changing parameters as like diameter, PML, thickness of gold (Au), sensing layer and pitch. The obtained result reveals that the proposed model may be used in biochemical and biological analyte detection to find out the important application.

Hollow-core silver coated photonic crystal fiber plasmonic sensor

We propose a simple hollow-core circular lattice photonic crystal fiber (PCF) based surface plasmon resonance (SPR) refractive index sensor. The sensing performance is investigated by using the finite element method (FEM). Silver is used as the plasmonic material for this design, which is placed on the outer surface of the PCF to facilitate the fabrication. The proposed sensor shows a maximum wavelength sensitivity of 4200 nm/RIU with a sensor resolution of 2.38 × 10−5 RIU. Besides, a maximum amplitude sensitivity of 300 RIU−1 and a resolution of 3.33 × 10−5 RIU is reported for an analyte refractive index of 1.37. Moreover, the effect of varying structural parameters on the sensing performance such as pitch, air hole diameter and silver layer thickness are also discussed thoroughly. Sensitivity analysis of the proposed sensor is performed in order to investigate the impact on loss depth and amplitude sensitivity. Thanks to high sensitivity and linearity characteristics, the proposed sensor can be potentially employed in practical bio-sensing and chemical sensing applications.

A Highly Sensitive Gold-Coated Photonic Crystal Fiber Biosensor Based on Surface Plasmon Resonance

In this paper, we numerically demonstrate a two-layer circular lattice photonic crystal fiber (PCF) biosensor based on the principle of surface plasmon resonance (SPR). The finite element method (FEM) with circular perfectly matched layer (PML) boundary condition is applied to evaluate the performance of the proposed sensor. A thin gold layer is deposited outside the PCF structure, which acts as the plasmonic material for this design. The sensing layer (analyte) is implemented in the outermost layer, which permits easy and more practical fabrication process compared to analyte is put inside the air holes. It is demonstrated that, at gold layer thickness of 40 nm, the proposed sensor shows maximum sensitivity of 2200 nm/RIU using the wavelength interrogation method in the sensing range between 1.33–1.36. Besides, using an amplitude interrogation method, a maximum sensitivity of 266 RIU−1 and a maximum sensor resolution of 3.75 × 10−5 RIU are obtained. We also discuss how phase matching points are varied with different fiber parameters. Owing to high sensitivity and simple design, the proposed sensor may find important applications in biochemical and biological analyte detection.

Design of ZBLAN photonic crystal fiber with nearly zero ultra-flattened chromatic dispersion for supercontinuum generation

In this paper, we present and numerically investigate Supercontinuum Generation (SCG) in ZBLAN circular lattice photonic crystal fiber with nearly zero ultra-flattened chromatic dispersion. The fiber dispersion properties are controlled by selectively liquid-filled and reduced air holes. The structure parameters have been optimized by using the fully vectorial finite-difference frequency-domain (FDFD) method combined with the perfectly matched layers (PML) boundary condition. Results indicate that a nearly zero ultra-flattened chromatic dispersion is obtained over a broad band of 300nm centered around 1.55μm with high nonlinearity and low confinement loss. Furthermore, SCG at 1.55μm is demonstrated with the optimized design. By using a 3.2kW peak power 100fs input secant-hyperbolic pulse, a symmetrical and relatively flat supercontinuum spectrum spanning 700nm in the range of 1200–1900nm is successfully generated.

Analysis of a new circular photonic crystal fiber with large mode area

A new design of large mode area (LMA) circular lattice photonic crystal fiber (CL-PCF) is proposed and numerically investigated. The cladding is formed by six rings of air holes arranged in circular configuration and the core is obtained by only omitting one air hole in the center. The transmission characteristics such as confinement loss, effective mode area, chromatic dispersion and bending loss are analyzed by using a finite difference in time domain (FDTD) method combined with perfectly matched layer (PML) boundary condition. Results show that around 1.55μm, the proposed CL-PCF exhibits an effective mode area larger than 1000μm2 with a confinement loss as low as 7.64×10−3dB/km for an air-filling fraction of dΛ=0.16. Furthermore, the effect of bending is reported and two new variants of CL-PCF are presented in the aim to mitigate its induced loss: CL-PCF with double air holes diameter in single side and CL-PCF with double cladding constant.

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.