Writing optical waveguides in fused silica using 1 kHz femtosecond infrared pulses

We have investigated the writing of waveguides in bulk pure fused silica glass with femtosecond Ti:Sapphire laser at 1 kHz repetition rate. The photoinduced tracks were characterized in terms of writing geometry (parallel and perpendicular), pulse duration (45 fs, 140 fs, and 200 fs), pulse energy (1–10 μJ), and translation speed (5–150 μm/s) of the sample. Under specific writing conditions, uniform buried waveguides with circular cross section, core diameter of 3–4 μm, and refractive-index change as large as 5×10−3 between core and cladding were achieved.