Direct grating writing: single-step Bragg grating and waveguide fabrication for telecommunications

Abstract

Direct Grating Writing (DGW) has been developed over the past decade as a means of rapidly prototyping waveguides with integrated Bragg grating structures in silica-on-silicon substrates. The technique allows complicated waveguide structures and Bragg grating arrays to be fabricated and characterised in-house.
Translating a photosensitive sample within the focus of a crossed UV beam arrangement induces a positive refractive index change, creating a channel waveguide. Modulating the intensity of the interference pattern creates the periodic refractive index change which forms a Bragg grating.
Recent work has developed techniques that apply integrated Bragg gratings to precisely characterize the loss and dispersion properties of the waveguides. The structures also produce devices for environmental sensing, detecting strain, temperature and chemical changes on the sample surface. Combining DGW with machining of the glass substrates has led to development of cantilever structures, which could be used for more advanced sensing applications. The system has also been used to inscribe gratings in novel substrates, such as the hybrid planar-fiber called 'flat fiber'.
We will present an overview of our recent DGW developments, highlighting new devices and alterations to the DGW system in order to further diversify the application of the process.

IONS NA-3 Stanford USA 13-15 Oct (2011)