Fabrication, characterization, and applications of laser-induced surface waveguides in fused silica

We irradiate the surface of pure fused silica with few-cycle pulses (duration < 10 fs, central wavelength at 800 nm, repetition of 400 kHz and a pulse energy of ca. 1 µJ) focused at a quasi grating incidence and observe a permanent densification in the irradiated region. A translation of the sample in the direction of the laser results in the direct writing of surface waveguides. The eigen modes of such structures exhibit a pronounced sensitivity to the refractive index of the immediate environment which we exploit to demonstrate direct refractive index sensing as well as plasmonic sensing.