A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Supercontinuum generation, photonic crystal fiber

http://ieeexplore.ieee.org/iel5/5/31325/01456922.pdf

An introduction to optical waveguides

Supercontinuum Generation in Optical Fibers: Preface

A plethora of research in recent years has been reported on biosensing in the surface plasmon resonant systems. However, very little research has reported a tunable and highly sensitive biosensor in a nanoscale platform. In this regard, we propose a nanoscale hyperbolic metamaterial (HMM)-based prism coupled waveguide sensor (PCWS) in the near-infrared range. The HMM layer makes up one of the constituents of the PCWS—comprised of a periodically arranged assembly of silver nanostrips. The structure is numerically simulated by the finite difference time domain method. It is demonstrated that the sensitivity of the reflected light can be tuned through the refractive index (RI) of the solution. Moreover, the effects of alteration of constituents of PCWS on the sensitivity have been analyzed. Results show that the sensitivity of PCWS can be harnessed by altering the thickness, slant angle of HMM layer, volume fraction (f) of metal in the HMM layer, and the incidence angle of light. For this purpose, the structure is numerically simulated by the finite difference time domain method. In the optimum design of the proposed sensor, the maximum value of sensitivity is achieved as high as S=3450  nm/refractive index unit with θ=10° and ϕ=10° and a metamaterial thickness of 250 nm. Moreover, the structure has a nanoscale footprint of 600  nm×400  nm×200  nm.

Nanoscale, tunable, and highly sensitive biosensor utilizing hyperbolic metamaterials in the near-infrared range.

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.

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

In this paper, an ultra-compact structure is presented for realization of all-optical NOT and XOR logic gates which can be compatible with silicon technology. Logic gates are based on two-dimensional photonic crystals, and the lattice constant and the radius of the rods are selected in such a way in order to operate the logic gates at 1550 nm. The proposed structure consists of three waveguides which are connected to each other using a T-shaped junction. This structure is optimized by two nano-resonators and has also two input ports and one output port. For our numerical studies, the plane-wave expansion and finite-difference time-domain methods have been used. The contrast ratios for the proposed all optical NOT and XOR logic gates are respectively 43.40 and 43.38 dB. The response time of the logic gates is 0.37 ps, which in turn creates a data transmission rate of 3.15 Tb/s. Our studies have shown that the NOT-designed logic gate is suitable for the use in optical integrated circuits.

Realization of all-optical NOT and XOR logic gates based on interference effect with high contrast ratio and ultra-compacted size

In this paper, photonic crystal ring resonators with hexagonal lattice structure are used to design a four-channel optical demultiplexer. The structure size, the average transfer coefficient, the quality factor, and the channel spacing are equal to 424.5 µm2, 95.8%, 1943, and 2 nm, respectively. The average crosstalk is also computed to be −18.11 dB. In this study, the plane wave expansion (PWE) and finite-difference time-domain (FDTD) methods are used, respectively, to characterize the photonic bandgap and to investigate the optical behavior of the structure. The proposed design can be used in dense wavelength division multiplexing (DWDM) systems.

Four-channel optical demultiplexer based on hexagonal photonic crystal ring resonators

Systematic engineering of a nanostructure plasmonic sensing platform for ultrasensitive biomaterial detection

In this study, a photonic crystal ring resonator with a triangular lattice is used to design an optical filter. The proposed structure is able to filter the central wavelength of 1548 nm with a transmission coefficient of over 95%. Moreover, this structure has an ultra-high-quality factor (Q) of about 1290. With altering the features of the structure including the refractive index, the lattice constant and the radius of the rods in the resonator core, their effects on the central wavelength of the filter, transmission coefficient, quality factor and bandwidth are investigated. The plane wave expansion and finite-difference time-domain methods are used to extract photonic band gap and investigate the photonic behavior of the proposed structure, respectively.

Ultra-high-Q optical filter based on photonic crystal ring resonator

Using a two-dimensional photonic crystal lattice, a compact and simple structure has been introduced in the present study to construct an all-optical half adder. The designed structure operates under the interference effect. The phase difference has been created in different states by putting the point defects and the difference in the length of the input waveguides. To do analyses, the finite-difference time-domain method and the plane wave expansion have been used. The advantages of this design include the small dimensions, high possibility of construction, compatibility with the silicon-based technology, and equality of the output power in the logic states 0 and 1. The contrast ratio calculated for the port Sum and the port Carry has been equal to 9.3 and 8.22 dB. The response time has been equal to 0.22 ps, generating the data transfer rate of 4.55 Tbps.

Mahmood Seifouri

Papers

Realization of all-optical NOT and XOR logic gates based on interference effect with high contrast ratio and ultra-compacted size

Four-channel optical demultiplexer based on hexagonal photonic crystal ring resonators

Systematic engineering of a nanostructure plasmonic sensing platform for ultrasensitive biomaterial detection

Ultra-high-Q optical filter based on photonic crystal ring resonator

Ultra-fast and compact all-optical half adder using 2D photonic crystals