Abstract
Long period gratings arc-induced in different types of fibre were annealed at 1000 degrees C for 24 h. During the annealing, the spectrum of the gratings written in Ge-doped fibres shifted towards longer wavelengths whereas an opposite shift was observed for gratings written in Ge-free fibres. A discussion on the mechanisms responsible for that behaviour is presented.

Abstract
Hybrid sol-gel planar optics devices for astronomy are produced for the first time. This material system can operate from the visible (0.5 mu m) up to the edge of astronomical J-band (1.4 mu m). The design, fabrication and characterization results of a coaxial three beam combiner are given as an example. Fringe contrasts above 94% are obtained with a source with spectral bandwidth of 50 nm. These results demonstrate that hybrid sol-gel technology can produce devices with high quality, opening the possibility of rapid prototyping of new designs and concepts for astronomical applications. (C) 2009 Optical Society of America

Abstract
Astronomical interferometry is an active area of research and an increasing number of new conceptual ideas and designs are being proposed to achieve optimum astronomical instruments. In particular, integrated optics has a lot to offer in what concerns beam combination and control. In this paper, different examples of application of hybrid sol-gel integrated optics devices for fabrication of beam combiners for astronomical applications is given. For the multiaxial beam combiners, a UV laser direct writing unit is used for mask fabrication. The operation principles of the coaxial combiners were validated using an interferometric set-up. Differential polarization and differential dispersion effects were minimized in this set-up to avoid any error in the characterization of the beam combiners. In all the devices, fringe contrasts above 90% were obtained with a source with spectral bandwidth of 50 nm. These results demonstrate that hybrid sol-gel technology can produce devices with high quality, opening the possibility of rapid prototyping of new designs and concepts for astronomical applications.

Abstract
Organic-inorganic hybrids were tailored as transparent monoliths and as planar waveguides deposited on borosilicate substrates by the spin coating technique. Laser direct writing process was used to create monomode Y-splitters. The Y-splitter structures were designed and optimized for a coupling ratio of 50% using a beam propagation method (BPM) software.. The potential of these optical structures based on di-ureasil hybrids to be used as optical filters operating in the C+L telecommunication windows will be evaluated.

Abstract
In this work we present a possible "way-to-go" for all-optical processing, shortening the distance between typical all-optical scenarios and real standardized optical networks. This is based on the usage of dualpolarization quadrature phase-shift keying (DP-DQPSK) for transmission with subsequent conversion to amplitude shift-keying for optical processing in metro/access network scenarios. In the last years, a strong push towards 100 Gbit/s technology developments has been done by major operators. The achieved developments indicate that future for high bit rate transmission in long-haul networks is reserved for phase modulation formats (like DP-QPSK) with coherent detection and subsequent electronic processing to mitigate transmission impairments. As this is becoming obvious for long-haul networks where high performance in transmission is required, the same is not applied to metropolitan networks. First of all the push for 100Gbit/s in metro hasn't been as strong as in long-haul (but it will come soon) and second, metro networks are much more cost sensitive and need less transmission performance, therefore the price of coherent detection and electronic processing might be difficult to realize when 100 Gbit/s come to the metro region. It can, therefore, be expected that amplitude modulation (AM) formats will still domain the metro area. Typical all-optical processing use AM signals which means that for metro networks there may still be a role for it. Recently, a transparent node connecting regio/metro to metro/access network rings was successfully demonstrated [1], [2]. There, full mux/demux between optical time domain multiplexed (OTDM) signals in regio/metro ring and wavelength division multiplexed (WDM) signals in metro/access was shown using AM signals. This experiment showed the potential of all-optical processing in terms of performance, cost and power savings. All-optical conversion between phase modulated (PM) and AM signals was demonstrated both with semiconductor optical amplifiers (SOAs) [3] and highly nonlinear fibres (HNLF) [4]. This means that, in principle, it is possible to merge the best of the two worlds; tight spectral occupation from long-haul DP- (D)QPSK and all-optical processing from AM signals in metro region. This might be the "way-to-go" for all optical processing. © 2009 IEEE.

Abstract
Phase-shifted Bragg Grating Waveguide filters were formed in bulk glass for the first time by femtosecond laser direct writing. A narrow, tunable 0.1-nm transmission window at 1550-nm is demonstrated for tunable p and other phase-shifts. © 2009 Optical Society of America.