Extending Femtosecond Laser Superfilamentation in Air with a Multifocal Phase Mask
Laser filamentation in air occurs when a strong laser causes ionization and plasma along the illumination channel. This can be useful for many applications, even for steering lighting! However, keeping a beam laser focused over extended atmospheric distances can be a challenging proposition.
In a recent article, a group of researchers from LOA in Paris has used Holo/Or multifocal DOEs, combined with their Vortex lens phase plates, to achieve extended super filamentation in air. Holo/Or are always excited to see their DOE elements used to push the boundaries of science with new applications. The article is entitled, “Extending femtosecond laser superfilamentation in air with a multifocal phase mask.”
The experimental setup includes a focused laser beam that is partially diffracted in a phase mask produced by Holo/Or. This enables the incident beam to be focused at multiple focal distances along the axis of propagation with equivalent laser energy.
The Abstract of this article states:
Laser filamentation is a spectacular phenomenon, where self-focusing of the laser pulse generates ionizing light channels. Many applications of filamentation, such as the laser lightning rod, require the generation of superfilaments, long plasma channels of higher electron density than normal filaments. Using a multifocal phase mask, we demonstrate an extension of the superfilamentation length of a focused terawatt laser beam. Optimized superfilaments show an increased energy deposition compared to a normal gaussian beam and an extension of their length by at least a factor two. When put in contact with a high voltage electrode, the guiding of a single plasma column with a length of ~1 m is observed. The length of an air waveguide generated by a vortex laser pulse is also increased by a factor 2 in the presence of the phase mask.
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Holo/Or develops, designs and manufactures diffractive optical elements (DOEs) and micro-optical elements for any wavelength, from DUV to far IR, as well as software/automation solutions for the design. Holo/Or’s products include:
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