Simultaneous spatial and temporal focusing for tissue ablation.

Simultaneous spatial temporal focusing (SSTF) is used to deliver microjoule femtosecond pulses with low numerical aperture geometries (<0.05 NA) with characteristics that are significantly improved compared to standard focusing paradigms. Nonlinear effects that would normally result in focal plane shifts and focal spot distortion are mitigated when SSTF is employed.

Intuitive analysis of space-time focusing with double-ABCD calculation.

We analyze the structure of space-time focusing of spatially-chirped pulses using a technique where each frequency component of the beam follows its own Gaussian beamlet that in turn travels as a ray through the system. The approach leads to analytic expressions for the axially-varying pulse duration, pulse-front tilt, and the longitudinal intensity profile. We find that an important contribution to the intensity localization obtained with spatial-chirp focusing arises from the evolution of the geometric phase of the beamlets.

Spatio-temporally focused femtosecond laser pulses for nonreciprocal writing in optically transparent materials.

Simultaneous spatial and temporal focusing (SSTF) provides precise control of the pulse front tilt (PFT) necessary to achieve nonreciprocal writing in glass wherein the material modification depends on the sample scanning direction with respect to the PFT. The PFT may be adjusted over several orders of magnitude. Using SSTF nonreciprocal writing is observed for a large range of axial focal positions within the sample, and nonreciprocal ablation patterns on the surface of the sample are revealed.

Temporally focused femtosecond laser pulses for low numerical aperture micromachining through optically transparent materials.

Temporal focusing of spatially chirped femtosecond laser pulses overcomes previous limitations for ablating high aspect ratio features with low numerical aperture (NA) beams. Simultaneous spatial and temporal focusing reduces nonlinear interactions, such as self-focusing, prior to the focal plane so that deep (approximately 1 mm) features with parallel sidewalls are ablated at high material removal rates (25 microm(3) per 80 microJ pulse) at 0.04-0.