Precision tuning of silicon photonic devices using multi-shot femtosecond laser irradiation

We demonstrate precision permanent tuning of silicon microring resonators using multi-shot femtosecond laser irradiation at 800 nm wavelength. By exploiting the incubation effect, we achieved finetuning of the microring resonance wavelength with a resolution of 2.5 pm per laser shot at a fluence of 0.0232 J/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. This represents 20 times finer resolution and 2 times lower fluence than previously demonstrated using single-shot femtosecond laser tuning.