BPU 12 Congress

Generation of Long-Range Quasi-Non-Diffracting Bessel-Gaussian Beams in Few-Cycle Femtosecond Laser Fields

Not scheduled

20m

Politechnica Univ

Oral Presentations

Speaker

Prof. Alexander Dreischuh (Department of Quantum Electronics, Faculty of Physics, Sofia University, Sofia, Bulgaria, National Centre of Excellence Mechatronics and Clean Technologies, Bulgaria, and Bulgarian Academy of Sciences, Sofia, Bulgaria)

Description

In this talk we will describe a new, simple and robust method for generating long-range Bessel-Gaussian beams with divergences on the microradian scale. The approach is entirely based on singular and Fourier optics. Initially, an optical vortex (OV) with a high topological charge (~20 and higher; [1]) is formed on the input Gaussian laser beam with a flat wavefront. Due to the modulation instability (which plays a positive role here), the vortices decay into single-charged ones. Repulsing, they transform the Gaussian beam into a ring-shaped beam with a large radius-to-width-ratio. Once the vortices are annihilated (erased), the ring-shaped beam is focused with a thin lens and a Bessel-Gaussian beam is sculpted behind the lens’ focus [2,3]. We will present experimental and numerical evidences supporting the claims that: (i) these beams are long-range and quasi-non-diffracting, (ii) can be generated in both - continuous-wave beams and in the fields of ultrashort (femtosecond) laser pulses [4], (iii) the approach is non-wavelength-selective, independently of the used approach for generation highly-charged OVs - spiral phase or spatial light modulators, and (iv) can be created in femtosecond laser fields by generating the second harmonic of ring-shaped, strongly azimuthally modulated necklace beams Fourier-transforming them in space [5]. We believe that these results are of interest for e.g. free-space optical communications.

This research is based upon work supported by the Bulgarian Ministry of Education and Science as a part of National Roadmap for Research Infrastructure, project ELI ERIC BG. The work was also supported by the Bulgarian National Science Fund (project KΠ-06-H78/6) and was achieved partially thanks to equipment provided by the European Regional Development Fund within the Operational Programme “Science and Education for Smart Growth 2014-2020” under the Project CoE “National center of mechatronics and clean technologies” BG05M2OP001-1.001-0008-C01.

References:
[1] L. Stoyanov et al., European Physical Journal Plus 138, 702 (2023).
[2] L. Stoyanov et al., Scientific Reports 10, 21981 (2020).
[3] L. Stoyanov et al., Optics Communications 480, 126510 (2021).
[4] L. Stoyanov et al., Optics Express 29, 10997 (2021).
[5] N. Dimitrov et al., Photonics 12, 119 (2025).