Femtosecond Laser Filaments for Use in Sub-Diffraction-Limited Imaging and Remote Sensing
Journal Article - Open Access
Texas A and M University College Station United States
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Probing remote matter with laser light is a ubiquitous technique used in circumstances as diverse as laser-induced breakdown spectroscopy andbarcode scanners. In classical optics, the intensity that can be brought to bear on a remote target is limited by the spot size of the laser at thedistance of the target. This spot size has a lower bound determined by the diffraction limit of classical optics. However, amplified femtosecondlaser pulses generate intensity sufficient to modify the refractive index of the ambient air and undergo self-focusing. This self-focusing effectleads to the generation of highly intense laser filaments which maintain their intensity and small sub-millimeter diameter size at distances wellbeyond the classical Rayleigh length. Such intensity provides the capability of remote scanning, imaging, sensing, and spectroscopy withenhanced spatial resolution. We describe a technique for generating filaments with a femtosecond regenerative chirped-pulse amplifier, and forusing the resulting filament to conduct imaging and spectroscopic measurements at remote distances of at least several meters.
- Lasers and Masers