Description
This project investigated spatiotemporal light springs (LS)—ultrashort, helical space--time wave packets generated by engineering a topological--spectral correlation in which the orbital angular momentum (OAM) varies with optical frequency. Building on a mode-by-mode construction of LS using Bessel--Gauss beams, the project expands LS tunability by introducing controlled spectral-phase (chirp) manipulation as an additional, experimentally relevant degree of freedom. A MATLAB simulation framework is developed in which the LS field is synthesized by coherently summing frequency modes with prescribed OAM and spectral phase, enabling full 3D visualization ($x$,$y$,$t$) of intensity isosurfaces and instantaneous-frequency maps. To reach the temporal sampling needed for frequency-resolved diagnostics, the code is substantially optimized by precomputing spatial modes and separating spatial and temporal loops, reducing computational cost from $O(N_{\text{time}}\times N_{\text{modes}})$ to $O(N_{\text{time}}+N_{\text{modes}})$, and further accelerated via GPU parallelization.
A key result is that treating spectral phase as sectorized (aligned with the discrete OAM/frequency sampling used in LS generation) makes chirp-like manipulation predictable and intuitive. Two independent controls are identified: step control, which reshapes the rotational structure and enables Angular Delay and Angular Delay Dispersion (including multi-helix "orbital dispersion" states), and slope control, which governs temporal placement and stretching via Longitudinal Delay and Longitudinal Delay Dispersion, including time-separated sub-LS synthesis through mode grouping. Finally, an LS platform incorporating supercontinuum broadening to access ultrabroadband regimes was developed in supporting laboratory work, motivating future applications in tailored ultrafast excitation and spectroscopy.
| Field of Research/Work | Atomic, Molecular, and Optical Physics |
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