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DIRECTED
ENERGY
PROFESSIONAL
SOCIETY
Abstract: 25-Symp-071
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UNCLASSIFIED, PUBLIC RELEASE
Curved air waveguides
An intense, ultrashort-pulse laser (USPL) beam, propagating in air, generates an extended, thin filament of dilute plasma [1]. Energy deposited by the laser pulse into the ionized region is transferred to the thermal energy or air molecules, and the subsequent thermodynamic evolution results in the formation of an extended “density hole” with a lifetime in the millisecond range [2,3]. If several of these density holes are spatially arranged to form a circle, they can act as a straight, long-lived optical waveguide for another, long-pulsed or quasi-continuous-wave laser beam [4]. In this contribution, we show how advanced beam engineering applied to a single USPL beam can be used to generate an air waveguide that follows an arbitrary curved trajectory instead of a straight line. We use a specially designed phase mask in combination with a conical lens (axicon) for the experimental demonstration of a curved optical air waveguide on a laboratory scale. In our experiment, the waveguide follows a parabolic trajectory and guides a forward-propagating visible laser beam over about 5 cm distance, deflecting it from a straight line by about 0.5 mm. This corresponds to the deflection angle of about 1 degree, which may not seem significant but will translate into a substantial transverse shift of the beam in the far field. Other beam trajectories can be straightforwardly realized [5]. We will discuss the limitations and potential for scalability of our approach that can be useful for long-range guidance of directed energy laser beams along non-trivial paths.
This work was supported by the US Army Research Office under contract #W9113M22D0061 and by the US Joint Directed Energy Transition Office (JDETO). JB acknowledges the support from SMART scholarship and from the DEPS scholarship grant.
References:
[1] Couairon, A. Mysyrowicz, “Femtosecond filamentation in transparent media,” Sci. Rep. 441, 47 (2007)
[2] N. Jhajj, E. Rosenthal, R. Birnbaum, J. Wahlstrand, and H. Milchberg, “Demonstration of long-lived high-power optical waveguides in air,” Phys. Rev. X 4, 011027 (2014)
[3] O. Lahav, L. Levi, I. Orr, R. Nemirovsky, J. Nemirovsky, I. Kaminer, M. Segev, and O. Cohen, “long-lived waveguides and sound-wave generation by laser filamentation,” Phys. Rev. A 90, 021801(R) (2014)
[4] A. Goffin, I. Larkin, A. Tartaro, A. Schweinsberg, A. Valenzuela, E. Rosenthal, and H. Milchberg, “Optical guiding in 50-meter-scale air waveguides,” Phys. Rev. X 13, 011006 (2023)
[5] J. Zhao, I. Chremmos, D. Song, D. Christodoulides, N. Efremidis, and Z. Chen, “Curved singular beams for three-dimensional particle manipulation,” Sci. Rep. 5:12086 (2015)
UNCLASSIFIED, PUBLIC RELEASE
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