## [#  Femtosecond laser microfabrication 

 ](/research-areas/femtosecond-laser-microfabrication)

We study the interaction of intense, femtosecond laser pulses with bulk transparent materials and use this interaction for material modification. The intensity of a femtosecond laser pulse can be high enough to cause nonlinear interactions between a transparent medium and the laser field. The material can strongly absorb energy from the laser field, producing free electrons in the material. This absorption can lead to damage or refractive index changes in the irradiated sample. The nature of the interaction between the laser pulse and the material depends on how the laser pulse is focused. When a powerful femtosecond laser pulse is tightly focused into a transparent sample, nonlinear absorption occurs only in the very small focal volume. This localization allows us to create patterns in three-dimensions inside transparent samples such as glass. For example, we have observed structures as small as 200-nm in diameter, offering exciting possibilities for high-precision microstructuring of transparent solids and for minimally disruptive laser nanosurgery.