Direct UV written planar waveguides in silica have been explored for over two decades . The technique is capable of fabricating low-loss channel waveguides, couplers and Bragg gratings by translating an appropriate substrate through a focused UV beam. To date direct UV written waveguides have been primarily formed by using 244nm laser light, relying on the photosensitivity provided by germanium doping, and also typically boron. To induce sufficient refractive index change necessary to form waveguides the substrates also require hydrogen and deuterium loading prior to UV writing . Not only does this require additional processing but over time the hydrogen present within the silica depletes, which can cause variation of the final written structures. Deep UV light at 213 nm has previously been used to inscribe strong fibre Bragg gratings (FBGs) in hydrogen-free Ge-doped fibres . Here we present the first use of a 213 nm UV laser to write planar waveguide devices without the need for hydrogen loading.
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