Femtosecond laser direct-write photoconductive patterns on tellurite glass

We report the formation of arbitrary photoconductive patterns made of tellurium (Te) nanocrystals by exposing a tellurite (TeO2-based) glass to femtosecond laser pulses. During this process, Te/TeO2-glass nanocomposite interfaces with photoconductive properties form on the tellurite glass substrate. We show that these laser-written patterns have a highly reproducible photo-response, from the near ultraviolet (263 nm) to the visible spectrum, stable over a few months. Specifically, high responsivity (16.55 A/W) and detectivity (5.25*10^11 Jones) of a single laser-written line pattern are measured for an illumination dose of 0.07 mW/cm^2 at 400 nm. This work illustrates a pathway for locally turning a tellurite glass into functional photoconductor of arbitrary shape, without adding materials and using a single laser process step.