Microstructured air-silica fibres: Recent developments in modelling, manufacturing and experiment

The main modelling methods devoted to microstructured air-silica optical fibres (MOFS) are presented and discussed. Then, the specific propagation properties ofMOFS are studied in detail. Characteristics measured on fibres manufactured in our laboratory or reported in the literature are analysed. A large number of potential and demonstrated applications are presented and the obtained performances are discussed. A particular attention is given to hollow-core photonic bandgap fibres and their applications.     

Low splice loss between 34 /spl mu/m core diameter Bragg fibre and G-652 fibre by using micro-optics

The splice loss at 1.55 /spl mu/m between a 34 /spl mu/m core diameter singlemode photonic bandgap fibre and a G-652 fibre has been dramatically reduced from 2.5 to 0.8 dB by using a micro-optics composed of graded-index and coreless pure silica fibres.     

Dual concentric core dispersion compensating fibre optimised for WDM application

A dual concentric core fibre exhibiting a chromatic dispersion coefficient around -350 ps/(nm km) is used in a dispersion compensating module designed for WDM application. The optimised length ratio is larger than 20 and the residual chromatic dispersion is measured at 0.4 ps/(nm km) in the C-band     

Very large effective area singlemode photonic bandgap fibre

A photonic bandgap fibre consisting of a 34 /spl mu/m diameter pure silica core surrounded by a periodic cladding has been modelled and characterised. It guides a robust HE/sub 11/ mode at 1.55 /spl mu/m with a 517 /spl mu/m/sup 2/ effective area and 0.4 dB/m propagation losses.     

Feasibility demonstration of low pump power operation for 1.48 mu m diode-pumped erbium-doped fibre amplifier module

An optimisation of the erbium-doped fibre greatly improves the 1.48 mu m pumping efficiency. The amplifier exhibits 26.2 dB fibre gain for 8 mW launched pump power and 20.2 dB gain for only 5.2 mW pump power, giving an outstanding 3.9 dB/mW gain coefficient.<>     

Optimal design of type-2 and type-1 fuzzy tracking controllers for autonomous mobile robots under perturbed torques using a new chemical optimization paradigm

This paper addresses the tracking problem for the dynamic model of a unicycle mobile robot. A novel optimization method inspired on the chemical reactions is applied to solve this motion problem by integrating a kinematic and a torque controller based on fuzzy logic theory. Computer simulations are presented confirming that this optimization paradigm is able to outperform other optimization techniques applied to this particular robot application.     

Flattening filter based on cascaded dual concentric core fibres

The use of dual concentric core fibres to realise a flattening filter is reported. The power spectrum of an ASE source has been flattened in the C-band from 5.8 to 1.4 dB.     

Application of acoustic microscopy to the measurement of some physical parameters of ceramics

The scanning acoustic microscope is a valuable tool for the ultrasonic non-destructive testing of ceramic materials or sintered metals, like titanium compounds. Bulk defects, responsible for the mechanical aging and breakdown of parts, are easily detected and imaged. Moreover, diffuse structures are evidenced in these images, forming a continuous background. In this paper, we present a method which enables the determination of physical parameters, like the density and the bulk grain size of the materials, from this background. This information is extracted, using a statistical approach, from the histograms pertaining to materials with a spectrum of different microstructures, based on a principal component analysis (PCA). It may be noted that the size of the microstructure elements accessible by this method can be lower than the spatial resolution of the microscope.     

1480-nm pumped erbium-doped fiber amplifiers with optimized noiseperformance for AM-VSB distribution systems

Within analog video transmission systems, optical amplifiers have to display simultaneously good noise and output power performance because of the very stringent carrier-to-noise ratio requirements imposed by the AM-VSB modulation format. We show, theoretically and experimentally, that properly designed forward 1480-nm pumped erbium-doped fiber amplifiers can deliver +16 dBm saturated output power with noise parameter (n_sp/C_x) as low as 3.5dB. These amplifiers do not exhibit significant degradation of their noise performance when the input powers are as large as +3 dBm. These characteristics make 1480-nm pumped amplifiers suitable for AM-VSB transmission systems