S. M. Abdur Razzak

Proposal for Highly Nonlinear Dispersion-Flattened Octagonal Photonic Crystal Fibers

A highly nonlinear photonic crystal fiber (HNL-PCF) based on an octagonal structure with isosceles triangular-latticed cladding is proposed for the telecommunication window. The finite-difference method with anisotropic perfectly matched boundary layer is used to investigate the guiding properties. It is demonstrated that it is possible to design a simple HNL low-loss dispersion-flattened PCF with a nonlinear coefficient of the order 27 W-1km-1 at a 1.55-mum wavelength. According to simulation, ultraflattened dispersion of 0 plusmn 0.5 ps/nm/km is obtained in a 1.46- to 1.66-mum wavelength with low confinement losses less than 0.06 dB/km in the entire band of interest.

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.

Novel Square Photonic Crystal Fibers with Ultra-Flattened Chromatic Dispersion and Low Confinement Losses

This study proposes a novel structure of index-guiding square photonic crystal fibers (SPCF) having simultaneously ultra-flattened chromatic dispersion characteristics and low confinement losses in a wide wavelength range. The finite difference method (FDM) with anisotropic perfectly matched layers (PMLs) is used to analyze the various properties of square PCF. The findings reveal that it is possible to design five-ring PCFs with a flattened negative chromatic dispersion of 0-1.5 ps/(nm.km) in a wavelength range of 1.27 μm to 1.7 μm and a flattened chromatic dispersion of 0±1.15 ps/(nm.km) in a wavelength range of 1.25 μm to 1.61 μm. Simultaneously it also exhibited that the confinement losses are less than 10 -9 dB/m and 10 -10 dB/m in the wavelength range of 1.25 μm to 1.7 μm.

Ultra-Low Material Loss and Dispersion Flattened Fiber for THz Transmission

This letter reports a photonic crystal fiber having ultralow material loss and near-zero dispersion at the telecom window which is suitable for THz wave guidance. The finite element method with perfectly matched layer circular boundary is used to investigate the guiding properties. The numerical results show that ultra-low material absorption loss of 0.056 cm-1 at 1.0 THz and nearly zero flattened dispersion of ±0.18 ps/THz/cm can be obtained from the proposed fiber in the wavelength range of 1.0-1.8 THz.

Design and Characterization of Highly Birefringent Residual Dispersion Compensating Photonic Crystal Fiber

A residual dispersion compensating octagonal photonic crystal fiber (OPCF), with an elliptical array of circular air-holes in the fiber core region, is proposed. The full-vector finite-element method with perfectly matched layer boundary is used as the analysis tool. It is demonstrated that it is possible to obtain large average negative dispersion of -562.52 ps/(nm · km) over 240 nm and -369.10 ps/(nm · km) over 630 nm wavelength bands for the fast and the slow axis, respectively. In addition to large negative dispersion, ultra-high birefringence, high nonlinearity, and zero-dispersion wavelengths with low confinement loss are also warranted. The proposed OPCFs would be a promising candidate for residual dispersion compensation, supercontinuum generation, and other applications.

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.

Design of large negative dispersion and modal analysis for hexagonal, square, FCC and BCC photonic crystal fibers

This paper presents a numerical design for confinement of light in the core to analysis mode profiles and negative dispersion with the variation of air fill fraction d/A (0.4 - 0.8) for hexagonal, square, face center cubic (FCC), body center cubic (BCC) photonic crystal fibers. Five ring silica-air micro structures are used for the dispersion analyses with finite difference time domain (FDTD) and 3D mode solver are used for mode profiles analysis. Mode confinement of the PCFs is found increases with the air fill fraction d/A but higher negative dispersion found for lower values. Best performance is found for Hexagonal PCF with higher mode confinement and Square for higher negative dispersion -381.9 ps/nm/km for d/A= 0.70 at 550 nm wavelength.

Tailoring polarization maintaining broadband residual dispersion compensating octagonal photonic crystal fibers

Abstract. We present a residual dispersion compensating highly birefringent photonic crystal fiber (PCF) based on an octagonal structure for broadband dispersion compensation in the wavelength range 1460–1625 nm. The finite element method with perfectly matched boundary condition is used as the numerical design tool. It has been shown theoretically that it is possible to obtain a negative dispersion coefficient of about −418 to −775  ps/nm/km over the S-, C-, and L-bands, relative dispersion slope (RDS) close to that of single mode fiber (SMF) of about 0.0036  nm−1 at 1550 nm. According to the simulation, birefringence of 2×10−2 is obtained at 1550-nm wavelength. The variation of structural parameters is also studied to evaluate the tolerance of the fabrication. The proposed octagonal PCF can be a potential candidate for residual dispersion compensation as well as maintaining single polarization in optical fiber transmission system.

Highly nonlinear polarization maintaining dispersion compensating fiber for high-speed transmission system

Abstract. A photonic crystal fiber design is presented, which has simultaneously ultra-high birefringence, high nonlinearity, and high negative dispersion. The relative dispersion slope matches with that of standard single-mode fiber of about 0.0036  nm−1. The finite element method with circular perfectly matched boundary layer is used to investigate the guiding properties. The proposed fiber ensures a large negative dispersion coefficient of about −639.16  ps/(nm km), birefringence of order 3.55×10−2, and nonlinear coefficient of 41  W−1 km−1 at 1550-nm wavelength.

Highly birefringent photonic crystal fibers with near-zero dispersion at 1550 nm wavelength

This paper presents highly birefringent photonic crystal fibers with simultaneously near-zero dispersion and low confinement losses. The finite difference time domain method with anisotropic perfectly matched layer boundaries is used as the simulation software. According to simulation, it is shown that photonic crystal fibers with hybrid cladding and artificial defects along one of the orthogonal axes sufficiently results in a very high birefringence of the order 10−2 which is two orders of magnitude higher than that of the conventional polarization maintaining fibers. Such a fiber also assumes both near-zero dispersion and low confinement losses at the 1550 nm wavelength. Optical fibers with novel properties such as high birefringence, near-zero dispersion, and low confinement losses may have applications in optical sensing applications.