Single-shot femtosecond-written segmented waveguides in amorphous materials

We explore the inscription of single-shot segmented waveguides in glasses using continuous trains of ultrashort laser pulses and fast scanning velocities. By varying the period, we show how the waveguide shape undergoes minor changes, but the overall index contrast, and therefore the guidance strength, can be controlled. On the applicative side, these waveguides allow an accurate control on the mode spatial extension, while preserving the overall shape and position of the fundamental mode. On the basic science side, owing to the suppression of cumulative effects, these waveguides are an ideal workbench for a reductionism-driven investigation of the highly nonlinear interaction responsible for the permanent modification.