Nguyen Hoang Hai

Broadband Dispersion Compensating Octagonal Photonic Crystal Fiber for Optical Communication Applications

We numerically report the design of a modified octagonal photonic crystal fiber (M-OPCF) for broadband dispersion compensation covering the C and L communication bands, i.e., wavelengths ranging from 1530 to 1625 nm. It was shown that the proposed broadband compensating PCF can be designed to simultaneously exhibit a high negative dispersion coefficient and a relative dispersion slope (RDS) close to that of a conventional single-mode optical fiber (SMF). From our results, it was found that the M-OPCF has a large negative dispersion [-226 to -290 ps/(nmkm)] over the C- and L-bands, and an RDS close to that of an SMF of about 0.0034 nm-1. In addition to this, the effective dispersion, residual dispersion, confinement loss, and polarization properties of the proposed PCF are also reported and discussed.

Design of Highly Nonlinear Birefringent Photonic Crystal Fibers with Ultra-Flattened Chromatic Dispersion

We present a new cladding design for the photonic crystal fibers in order to achieve simultaneously high nonlinearity, dispersion-flattened characteristic, low confinement loss, and polarization maintaining properties. The finite difference method with anisotropic perfectly matched boundary layer is used as the numerical design tool. A nonlinear coefficient of the order 35 W-1 km-1 is obtained with a high birefringence of the order 1.5×10-4 at a 1550 nm wavelength. Ultra-flattened dispersion of 0±0.31 ps nm-1 km-1 is also obtained in a 1440 to 1600 nm wavelength range with low confinement losses less than 0.05 dB/m in the entire dispersion-flat band.

New proposal of chromatic dispersion control in honey comb photonic crystal fiber for broadband communication

This article presents a photonic crystal fibers (PCFs) that has a high-index core surrounded by air hole with Honey Comb structure and different air hole diameters surrounding core region. The proposed design module has been simulated through an efficient full vector modal solver based on the finite-difference method with anisotropic perfectly matched layers absorbing boundary condition. Through optimizing only three geometrical parameters, two air hole diameters, and pitch, the nearly zero ultra-flattened dispersion PCFs, as well as small effective area can be efficiently designed. We then analyze the sensitivity of the dispersion slope to small variations from the optimum value of specific structural parameters. The designed index-guiding Honey Comb-PCFs has a nearly zero ultra-flattened dispersion of 0±0.2 ps/(nm.km) in a wavelength range of 1.39 μm to 1.7 μm and effective mode area less than 34 μm2 in all wavelength range resulting extremely small splice loss with conventional single mode fiber.

Tellurite nanowire core photonic crystal fiber

Optical properties of tellurite nanowire core photonic crystal fiber (PCF) are compared with silica and germanium-doped core PCFs. Using finite element method (FEM) with a circular perfectly matched boundary layer (PML), superior performance of tellurite nanowire core PCF is reported to design highly nonlinear and high numerical aperture (NA) PCF. With the same structural dimension, tellurite nanowire core PCF is found to be 14.5 times higher nonlinear coefficient compared to pure silica core PCF and 7.5 times higher nonlinear coefficient compared to 3% germanium (Ge)-doped core PCF. In addition, tellurite nanowire core PCF shows higher NA compared to pure silica core PCF and 3% Ge-doped core PCF. Moreover, zero-dispersion manipulating techniques of tellurite nanowire core PCF are briefly described with simulation results.

Light source design using hollow core photonic crystal fibers

Comparing optical properties of hollow core photonic crystal fibers (PCFs), Kagome-lattice hollow core PCF is used to design supercontinuum (SC) light sources for optical coherence tomography systems. By filling high pressure xenon (Xe) through the hollow core of Kagome-lattice PCF, nonlinearity has been increased considerably. Using finite element method with perfectly matched layer, SC spectra at 1.0 and 1.31 μm in normal chromatic dispersion region have been generated using picosecond optical pulses produced from relatively less expensive laser sources.

A novel design of highly nonlinear golden spiral Ge-doped core photonic crystal fiber for supercontinum light sources application

This paper presents a design of an Index-guiding Fiber using air holes arranged in Golden spiral lattice and a higher refractive index Germania (GeO2) core (GGS-PCF), with all normal group velocity dispersion (GVD) and high nonlinear coefficient to generate light sources based on Supercontinum Generation. By placing a Ge-rod inside, near the center of the core, we increase the nonlinear coefficient to 108 W-1km-1 at 1.55μm. In Simulation, we used Finite Element Method (FEM) with a circular Perfect Matched Layer boundary (PML) to calculate the electric field and modal effective index. Then the process of solving nonlinear Schrodinger equation was studied to obtain spectrum property after propagating picosecond sech2 pulses through 80m of fiber length. And the result has shown that this GGS-PCF can be usefully exploited in light source applications.

Novel design of hybrid cladding hexa-octagonal photonic crystal fiber with dispersion control for broadband communication

This paper proposes a novel structure for dispersion controlling and low confinement losses with a hybrid core hexagonal-octagonal photonic crystal fiber (6/8-PCF). By including hexagonal rings lattices structure in the cladding region of the conventional O-PCF and adjusting the size of air holes around the two innermost cladding structure, we can successfully design low flattened PCF with low confinement loss. The influence of design parameters on the properties of chromatic dispersion, confinement loss, effective area of the hybrid cladding HO-HPCF is also investigated. The low flattened dispersion feature, as well as the low confinement losses is the main advantages of the proposed PCF structure, making it suitable as chromatic dispersion controller/compensator for broadband communication system.

High numerical aperture square lattice structure photonic crystal fiber for optical coherence tomography

In optical coherence tomography (OCT) system, high numerical aperture (NA) PCF is required for collecting back scattering light for detailed information from body tissue. In this paper, we propose a new structure of high NA zero dispersion single mode photonic crystal fiber (PCF) for OCT at 0.83 μm, 1.06 μm and 1.31 μm wavelengths which are used for ophthalmology, dermatology and dentistry, respectively. The properties of the proposed PCF are simulated by using finite difference method (FDM) with an anisotropic perfectly matched boundary layer. The PCF offers not only high NA but also both zero dispersion and single mode operation at each center wavelengths. Simulation results show that the designed PCF at target wavelengths improves the transverse resolution of OCT systems.

Guiding Properties of Modified Triangular Lattice Photonic Crystal Fibers

We present guiding properties of modified triangular lattice photonic crystal fibers. The finite difference method under anisotropic perfectly matched layer boundary condition is used to investigate the guiding properties. Dispersion and effective area properties of the proposed fibers are presented for different pitches and air-hole diameters. From the results of simulation, for a small pitch, the effective area of the proposed fibers around 1550 nm telecommunication window is found to be different than that of other fibers reported to date. The dual-slope effective area of the proposed fibers within the telecommunication window may be suitable for designing highly nonlinear fibers for various applications in nonlinear regimes. Moreover, large negative dispersion magnitude and slope are also found near 1550 nm wavelength.