Femtosecond laser microfabrication is a high-precision technique that leverages ultrashort laser pulses to process materials at the microscale. The laser beam emerging from the femtosecond laser source is first modulated using a combination of beam expanders and focusing optics to achieve a tightly focused spot size ranging from approximately 5 to 100 micrometers, depending on the application and material system. This focused beam is then directed onto the target substrate mounted on a high-precision xyz stage, allowing for controlled patterning in two or three dimensions.

The extremely short pulse duration and high peak intensities ensure that the energy is deposited into the material within a very brief time interval. This ultrafast energy deposition leads to nonlinear absorption mechanisms, such as multiphoton ionization and avalanche ionization, especially in transparent or wide band-gap materials. These mechanisms can induce localized phase transformation, ablation, or even micro-explosions in the focal region, enabling precise removal or modification of material.

Due to the femtosecond pulse duration, there is minimal thermal diffusion to the surrounding material, which significantly reduces the heat-affected zone (HAZ). This thermal confinement is crucial for achieving high spatial resolution and avoiding thermal damage, making it suitable for microstructuring sensitive materials such as polymers, glasses, semiconductors, and biological tissues.