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The article presents a direct grating writing technique that allows simultaneous ultraviolet (UV) definition of channel wave guides with integral Bragg gratings in a photosensitive planar media. Based on a small-spot interference pattern generated by two focused UV-writing beams, the single-step approach was developed to promote optimal use of sample photosensitivity for both the wave guide geometry and Bragg grating superstructure, with the potential for implementing many aspects of advanced grating design, such as chirp and apodisation, without the need for a phase mask.

An integrated direct UV written apodised planar Bragg grating reflector with 154 GHz (1.23 nm) of thermo-optic tuning in the C-band and a response speed 31 GHz/ms is demonstrated. The degree and speed of tuning of the fabricated device indicates potential application in dynamic optical networks, as an optical add-drop multiplexer. [ABSTRACT FROM AUTHOR]

A method for fabricating planar silica substrates via modified chemical vapour deposition (MCVD) and a modified fibre drawing technique is presented. Long lengths of planar material are generated from a single substrate offering a potentially low-cost alternative to existing planar substrate deposition processes. Buried straight and splitting waveguide channels, as well as Bragg gratings, are inscribed in the planar material using direct UV-writing technology, and the results are reported. [ABSTRACT FROM AUTHOR]

Presented is a study of low polarisation sensitivity 2° X-couplers with 20% coupling ratio tuning via refractive index asymmetry, attaining 50:50 power splitting at 1550 nm. The device has less than 5% coupling ratio variation over 30 nm in the C-band and <0.7 dB polarisation-dependent loss. [ABSTRACT FROM AUTHOR]