Impact of linear mode coupling on the group delay spread in few-mode fibers

We report an investigation on the group delay spread in few-mode fibers operating in the weak and strong linear coupling regimes, and for the first time, we study the transition region between them. A single expression linking the group delay spread to the fiber correlation length is validated for any coupling regime, considering 3 guided modes.

Toward a new generation of photonic humidity sensors

This review offers new perspectives on the subject and highlights an area in need of further research. It includes an analysis of current scientific literature mainly covering the last decade and examines the trends in the development of electronic, acoustic and optical-fiber humidity sensors over this period. The major findings indicate that a new generation of sensor technology based on optical fibers is emerging. The current trends suggest that electronic humidity sensors could soon be replaced by sensors that are based on photonic structures. Recent scientific advances are expected to allow dedicated systems to avoid the relatively high price of interrogation modules that is currently a major disadvantage of fiber-based sensors.

Nonlinearity compensation via spectral inversion and digital back-propagation:a practical approach

We report performance enhancements enabled by pre-dispersed spectral inversion equivalent to that of ideal back-propagation, with further x2 increase in reach from multi-channel compensation, with spectral inversion employed upto 400km (from mid-link) with <1dB penalties. © 2012 OSA.

Gain switched multi-carrier transmitter and pilot tone based receiver for long reach access networks

A novel and cost effective long reach PON downlink scenario is proposed employing a multi-carrier transmitter and pilot tone aided direct detection at the receiver. Error free performance with QPSK and 50km transmission is presented. © 2012 OSA.

Highly birefringent long period gratings fabricated with femtosecond laser

Long Period Gratings (LPG) in standard fibre have been manufactured with a sharply focused near infrared (NIR) femtosecond laser beam. Polarization splitting of the attenuation bands is strongly dependent upon the inscription power.

Femtosecond laser inscribed phase masks for fibre Bragg grating sensor inscription

We present femtosecond laser inscribed phase masks for the inscription of Bragg gratings in optical fibres. The principal advantage is the flexibility afforded by the femtosecond laser inscription, where sub-surface structures define the phase mask period and mask properties. The masks are used to produce fibre Bragg gratings having different orders according to the phase mask period. The work demonstrates the incredible flexibility of femtosecond lasers for the rapid prototyping of complex and reproducible mask structures. We also consider three-beam interference effects, a consequence of the zeroth-order component present in addition to higher-order diffraction components. © 2012 SPIE.

112Gbit/s RF assisted dual-carrier DP-16-QAM in installed and new build WDM applications

The performance of a 112Gbit/s dual-carrier DP-16-QAM channel in various WDM configurations is characterized. Variations of the dispersion map, ROADM count and system length are experimentally evaluated and compared with numerical simulation. © 2012 OSA.

Transverse loading of multicore fibre gratings

We report experimental measurements of the reflection spectra of Bragg gratings inscribed in 4-core fibres under transverse loading. Broadening and splitting of the Bragg peaks from each core are observed as a function of load and fibre orientation.

Tunable dispersion slope compensator using novel tailored Gires-Tournois etalons

We present a novel concept of tailored GTE structure and show that such devices are very useful for the realization of DSC with almost arbitrary dispersion profile and also with tunability in dispersion slope.

5,745 km DWDM transcontinental field trial using 10 Gbit/s dispersion managed solitons and dynamic gain equalization

Error free unregenerated transmission is demonstrated looped-back over 5,745 km (62 spans) of installed SSMF along the Adelaide-Perth leg of the IP1 Australia network, which is now the world's longest commercially deployed unregenerated 10 Gbit/s DWDM terrestrial transmission system. © 2000 Optical Society of America.

High sensitivity sensors utilising characteristics of dispersion-turning-point of long-period gratings in B/Ge co-doped fibre

Systematically investigated the waveguide dispersion characteristics of LPFGs. It has been revealed that the coupled cladding modes resonating in the dispersion-turning-point region are intrinsically sensitive to the external perturbation. Thus, LPFG-based application devices requiring good stability should avoid this region. On the other hand, this mode ultra-sensitive-zone can be explored to realise sensors and tuneable filters of high efficiency.

Highly birefringent long period gratings fabricated with femtosecond laser

Long Period Gratings (LPG) in standard fiber have been manufactured with a sharply focused near infrared (NIR) femtosecond laser beam. Polarization splitting of the attenuation bands is strongly dependent upon the inscription power.

Full-field feed-forward equalizer with adaptive system optimization

We numerically investigate the combination of full-field detection and feed-forward equalizer (FFE) for adaptive chromatic dispersion compensation up to 2160 km in a 10 Gbit/s on-off keyed optical transmission system. The technique, with respect to earlier reports, incorporates several important implementation modules, including the algorithm for adaptive equalization of the gain imbalance between the two receiver chains, compensation of phase misalignment of the asymmetric Mach-Zehnder interferometer, and simplified implementation of field calculation. We also show that in addition to enabling fast adaptation and simplification of field calculation, full-field FFE exhibits enhanced tolerance to the sampling phase misalignment and reduced sampling rate when compared to the full-field implementation using a dispersive transmission line.

Surface nanoscale axial photonics:robust fabrication of high-quality-factor microresonators

Recently introduced surface nanoscale axial photonics (SNAP) makes it possible to fabricate high-Q-factor microresonators and other photonic microdevices by dramatically small deformation of the optical fiber surface. To become a practical and robust technology, the SNAP platform requires methods enabling reproducible modification of the optical fiber radius at nanoscale. In this Letter, we demonstrate superaccurate fabrication of high-Q-factor microresonators by nanoscale modification of the optical fiber radius and refractive index using CO laser and UV excimer laser beam exposures. The achieved fabrication accuracy is better than 2Å in variation of the effective fiber radius. © 2011 Optical Society of America.

Fibre optic sensors for high speed hypervelocity impact studies and low velocity drop tests

The initial aim of this project was to develop a non-contact fibre optic based displacement sensor to operate in the harsh environment of a 'Light Gas Gun' (LGG), which can 'fire' small particles at velocities ranging from 1-8.4 km/s. The LGG is used extensively for research in aerospace to analyze the effects of high speed impacts on materials. Ideally the measurement should be made close to the centre of the impact to minimise corruption of the data from edge effects and survive the impact. A further requirement is that it should operate at a stand-off distance of ~ 8cm. For these reasons we chose to develop a pseudo con-focal intensity sensor, which demonstrated resolution comparable with conventional PVDF sensors combined with high survivability and low cost. A second sensor was developed based on 'Fibre Bragg Gratings' (FBG) which although requiring contact with the target the low weight and very small contact area had minimal effect on the dynamics of the target. The FBG was mounted either on the surface of the target or tangentially between a fixed location. The output signals from the FBG were interrogated in time by a new method. Measurements were made on composite and aluminium plates in the LGG and on low speed drop tests. The particle momentum for the drop tests was chosen to be similar to that of the particles used in the LGG.