Redwan Ahmad

Extremely High-Birefringent Asymmetric Slotted-Core Photonic Crystal Fiber in THz Regime

We present a thorough numerical analysis of a highly birefringent slotted porous-core circular photonic crystal fiber (PCF) for terahertz (THz) wave guidance. The slot shaped air-holes break the symmetry of the porous-core which offers a very high birefringence whereas the compact geometry of the circular cladding confines most of the power in the fiber-core. The fiber structure reported in this letter exhibits simultaneously ultrahigh modal birefringence of 7.5 × 10-2 and a very low effective absorption loss of 0.07 cm-1 for y-polarization mode at an operating frequency of 1 THz. It is highly anticipated that the slotted-core waveguide would be of very much convenience in many polarization maintaining THz appliances.

Residual dispersion compensation over the S + C + L + U wavelength bands using highly birefringent octagonal photonic crystal fiber

An octagonal photonic crystal fiber (PCF) with an elliptical shape in the center core is numerically investigated for residual dispersion compensation in the wavelength range 1460-1675 nm. The designed fiber exhibits flattened negative dispersion over the S + C + L + U wavelength bands and an average dispersion of -465.5 ps/(nm·km) with an absolute dispersion variation of 10.5 ps/(nm·km). In addition, the proposed PCF shows a high birefringence of 2.68×10(-2) at the operating wavelength 1550 nm, which meets the requirement of high birefringence. Moreover, the variation of two air holes in the first ring up to 5% ensures an average dispersion of -491.5 ps/(nm·km) with a dispersion variation of 13 ps/(nm·km), and birefringence reaches up to 3×10(-2). Furthermore, to evaluate the sensitivity of the fiber dispersion properties, ±5% variation in the optimum parameters is studied.

Relative dispersion slope matched dispersion compensating highly birefringent spiral microstructure optical fibers using defected core

Abstract. A highly birefringent dispersion compensating microstructure optical fiber (MOF) based on a modified spiral (MS)-MOF is presented that successfully compensates the dispersion covering the E- to L-communication bands ranging from 1370 to 1640 nm. It is shown theoretically that it can obtain a negative dispersion coefficient of about −221 to −424  ps/(nm·km)) over S to L bands and −327  ps/(nm· km)) at the operating wavelength of 1550 nm. The relative dispersion slope is perfectly matched to that of single-mode fiber of about 0.0036  nm−1. Besides, the proposed MS-MOF offers high birefringence of 1.79×10−2 with a large nonlinear coefficient of about 41.8  W−1 km−1 at the operating wavelength along with two zero dispersion wavelengths at 610 and 1220 nm. Futhermore, the variation of structural parameters is also studied to evaluate the tolerance of the fabrication.

Bend-Insensitive and Low-Loss Porous Core Spiral Terahertz Fiber

A novel (to the best of our knowledge) kind of porous-core spiral photonic crystal fiber (PCF) is proposed in this letter. It illustrates a tradeoff managed between material absorption and bending loss for efficient guidance of terahertz (THz) waves using a circular lattice array of smaller air-holes inside the core of an equiangular spiral structure. With maximum porosity and operating frequency of 1 THz, bending loss of 4.16×10-16 cm-1 and effective material loss of 0.1 cm-1 are reported. In addition, other modal characteristics, such as effective area, confinement loss, and fabrication techniques of the proposed fiber have been discussed. The proposed THz waveguide can be potentially used for efficient and convenient transmission of THz waves.

Proposal for highly residual dispersion compensating defected core decagonal photonic crystal fiber over S+C+L+U wavelength bands

Abstract. A defected core decagonal photonic crystal fiber is designed and numerically optimized to obtain its residual chromatic dispersion compensation in the wavelength range of 1460 to 1675 nm i.e., over S+C+L+U wavelength bands having an average dispersion of about −390  ps/(nm km) with a dispersion variation of 7  ps/(nm km). The designed fiber, with a flattened dispersion profile, has four rings of holes in the cladding region, which results in low confinement loss and small effective mode area at wavelength 1550 nm. For residual chromatic dispersion compensation, the proposed fiber can be used in wavelength division multiplexing optical fiber data communication systems.

A defected core highly birefringent dispersion compensating photonic crystal fiber

In this paper we propose a defected core Photonic Crystal Fiber (PCF) having circular lattice that ensures Residual Dispersion Slope (RDS) matched negative dispersion covering S+C+L communication bands with high birefringence for sensing purpose. The results show that this PCF has an average value of negative dispersion of -331 ps/nm-km & offers high birefringence of 2.75×10-2 with relative dispersion slope (RDS) perfectly matched to that of single mode fiber of about 0.0036 nm-1 at the wavelength 1550 nm. Due to its optical properties, the proposed fiber can be considered as an excellent candidate for sensing applications by maintaining single polarization along with dispersion compensation in optical fiber transmission system.

Design of polarization-maintaining photonic crystal fibre for dispersion compensation over the E+S+C+L telecom bands

We investigate numerically a defected-core hybrid photonic crystal fibre (H-PCF) with a circular core and a rectangular-shaped cladding, which is designed for compensation of residual dispersion over a wide wavelength range. Our simulation results testify that this H-PCF exhibits a large negative dispersion (- 868 ps/(nm km)) over the E+S+C+L telecommunication bands, with the relative dispersion slope perfectly matching that of a single-mode fibre at the operating wavelength 1550 nm. The H-PCF reveals the birefringence 1.06×10 -2 at the operating wavelength. In order to evaluate the sensitivity of optical properties of our H-PCF, we study the effect of variations of its parameters as large as ±2% from their optimal values. Due to its specific characteristics, the H-PCF suggested in this work can be considered as an excellent candidate for compensating dispersion, maintaining a single polarization in the optical fibre transmission systems, and numerous optical sensing applications.

Design of a square lattice photonic crystal fiber for dispersion compensation over telecom bands

In this paper, we numerically demonstrate a large negative dispersion with highly birefringent square lattice photonic crystal fiber (SLPCF) in the entire telecom wavelength bands. Finite element method with perfectly matched layer boundary condition is used to evaluate the modal properties of the fiber. Numerical results reveal that it is possible to obtain a large negative dispersion coefficient of -897 ps/(nm.km), a relative dispersion slope (RDS) close to that of single mode fiber (SMF) of about 0.0036 nm-1 and birefringence of the order 1.34×10-2 at 1.55 μm. To evaluate the tolerance of fabrication variation of structural parameters from their optimum value is carried out.

Design of a photonic crystal fiber for dispersion compensation over telecommunication bands

This paper presents a microstructure optical fiber based on an hexagonal structure for dispersion compensation in a wideband transmission system. According to simulation, negative dispersion coefficient of - 562 ps/(nm.km) and relative dispersion slope (RDS) close to that of single mode fiber (SMF) of about 0.0036 nm-1 is obtained at 1550 nm wavelength. Besides the proposed hexagonal microstructure optical fiber (H-MOF) offers high birefringence of 3.06×10-2. Due to having better optical properties, this proposed fiber can be effectively used in broadband dispersion compensation and sensing applications.

A slope matched microstructure optical fiber for dispersion compensation over S + C+ L wavelength bands

This paper presents a microstructure optical fiber based on an octagonal structure for dispersion compensation in a wide range of wavelengths. It is shown theoretically that it is possible to obtain negative dispersion coefficient of - 821 ps/(nm.km) and relative dispersion slope (RDS) close to that of single mode fiber (SMF) of about 0.0036 nm-1 at 1550 nm wavelength. Besides the proposed octagonal microstructure optical fiber (O-MOF) offers high birefringence of 1.86×10-2. Due to having superior optical properties, this proposed fiber with modest number of design parameters can be effectively used in broadband dispersion compensation and sensing applications.