Investigation into the writing dynamics of planar Bragg gratings using pulsed 213 nm radiation

We present the first substantive investigation into the photosensitivity response of planar-doped silica to pulsed 213 nm light. We look at the response over a broad range of fluences and average powers to identify suitable regimes for simultaneous waveguide and Bragg grating writing. Unlike previously reported work, we do not observe any clear evidence of a similar non-linear photosensitivity response in B/Ge doped silica. We discuss laser-induced damage, saturation of photosensitivity, and grating response. This paper presents writing regimes for small spot direct UV writing where the photosensitivity and grating response are optimum, thereby confirming the suitability of the fabrication approach for complex devices.