Abstract
In this paper we examine the birefringence of buried optical waveguides written with femtosecond lasers in bulk fused silica glass. We report two modes of low and high birefringence associated with strong form birefringence and the orientation of nanogratings that align perpendicular to the writing laser polarization. The birefringence and waveguide losses are characterized over various laser exposure conditions to facilitate the fabrication of low-loss and compact wave retarders and polarization beam splitters for integration into polarization controlled circuits. Zero-order quarter-wave and half-wave retarders together with polarization beam splitters are demonstrated, all operating at telecom wavelengths. Integration of such devices is targeted for application in photonic quantum circuits. © 2012 SPIE.

Abstract
Hybrid sol-gel technology was used for fabrication of prototypes of coaxial two, three and four telescopes beam combiners for astronomical applications. These devices were designed for the astronomical J-band and have been characterized using an optical source with emission centered at 1265 nm and with a spectral FWHM of 50 nm. Interferometric characterization of the two, three and four beam combiners, showed average contrasts respectively higher than 98%, 96% and 95%. Interferometric spectral analysis of the beam combiners revealed that the chromatic differential dispersion is the main contributor to the observed contrast decay in the latter cases. The laser direct writing technique was used for fabrication of a coaxial two beam combiner on sol-gel material; it showed a contrast of 95%. The measured high contrast fringes confirm that the procedures used lead to performant IO beam combiners. These results demonstrate the capabilities of the hybrid sol-gel technology for fast prototyping of complex chip designs for astronomical applications.

Abstract
OTDM-to-WDM conversion from 128.1 Gbit/s to 3x42.7Gbit/s is achieved by wavelength conversion using side filtering of SPM broadened spectrum in HNLF, followed by a single electro-absorption modulator based optical gate. A maximum 2dB penalty was achieved. (C) 2008 Optical Society of America.

Abstract
Fabrication of organic-inorganic sol-gel glass channel waveguides by ultraviolet (UV) photopolymerization of material synthesized from the precursor methacryloxypropyltrimethoxysilane is performed using a pulsed 248-nm excimer laser without the need of photoinitiators. The transmission spectra of channel waveguides are presented. Absorption bands are identified, revealing high loss (4-5 dB/cm) at 1.55 mum mainly due to strong OH group content and an acceptable value of 0.4 dB/cm at 1.3 mum. Heat treatment and UV irradiation showed similar effects on the transmission spectra of channel waveguides, revealing no loss improvement in the 1.55-mum region.

Abstract
The fabrication and characterization of long-period gratings (LPGs) in fiber tapers is presented alongside supporting theory. The devices possess a high sensitivity to the index of aqueous solutions due to an observed spectral bifurcation effect, yielding a limiting index resolution of +/- 8.5 x 10(-5) for solutions with an index in the range 1.330-1.335.

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.