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X-ORIGINAL-URL:https://sites.gtiit.edu.cn/physicsprogram/
X-WR-CALNAME:Department of Physics 
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UID:MEC-e22312179bf43e61576081a2f250f845@sites.gtiit.edu.cn
DTSTART:20251125T183000Z
DTEND:20251125T193000Z
DTSTAMP:20251118T085000Z
CREATED:20251118
LAST-MODIFIED:20251118
PRIORITY:5
TRANSP:OPAQUE
SUMMARY:Physics Graduate Student Seminar seminar
DESCRIPTION:Title: Exploring nonlinear light-matter interaction processes with orbital angular momentum beams\nSupervisors: Prof. Marcelo Ciappina (GTIIT) and Prof. Michael Krueger (Technion)\nSpeaker: Bikash Kumar Das (PhD Student in Physics)\nZoom link: https://technion.zoom.us/j/97851719100\nAbstract\nOptical vortices, light beams carrying orbital angular momentum (OAM), have reshaped modern photonics, yet their use in strong-field physics and non-linear optics is only beginning to unfold. Intense laser–matter interactions such as high-order harmonic generation (HHG) and above-threshold ionization with OAM beams have revealed coherent control of HHG in gases, including robust OAM transfer, conserved divergence across harmonic orders, and even the formation of twisted attosecond pulses. However, most studies rely on conventional vortex beams, where increasing OAM reduces peak intensity and limits efficient high-order harmonic generation.\nTo overcome this limitation, we investigate HHG driven by perfect optical vortex (POV) beams, whose intensity distribution is independent of OAM. Using a multiscale model, we show that POV beams can generate short-wavelength harmonics with very high OAM, maintaining similar divergence and following the linear OAM-scaling law. By superposing linearly polarized OAM beams with different waists or amplitudes, we further demonstrate flexible control of the harmonic OAM and derive a generalized OAM selection rule.\nWe also extend our analysis to solid-state HHG in ZnO using a dedicated theoretical framework that reproduces experimental observations and enables the synthesis of attosecond vortices. Altogether, these results highlight new opportunities for generating high-OAM vortex beams from the visible to deep-UV, broadening the scope of strong-field, attosecond physics and ultrafast photonics.\n
URL:https://sites.gtiit.edu.cn/physicsprogram/events/physics-graduate-student-seminar-seminar/
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