"Molecular waveplate" for the control of ultrashort pulses carrying orbital angular momentum

TL;DR

This paper introduces a novel molecular waveplate technique that uses non-adiabatic molecular alignment to generate and control broadband ultrashort vortex pulses carrying orbital angular momentum, overcoming limitations of traditional optical elements.

Contribution

The authors present a new method employing vector beam-induced molecular alignment to create a tunable, broadband molecular waveplate for ultrashort vortex pulse generation, enhancing control and efficiency.

Findings

Efficient conversion of circularly polarized light into OAM pulses.

Generation of few-cycle, high-intensity vortex beams.

Broad spectral range adaptability of the molecular waveplate.

Abstract

Ultrashort laser pulses carrying orbital angular momentum (OAM) have become essential tools in Atomic, Molecular, and Optical (AMO) studies, particularly for investigating strong-field light-matter interactions. However, controlling and generating ultrashort vortex pulses presents significant challenges, since their broad spectral content complicates manipulation with conventional optical elements, while the high peak power inherent in short-duration pulses risks damaging optical components. Here, we introduce a novel method for generating and controlling broadband ultrashort vortex beams by exploiting the non-adiabatic alignment of linear gas-phase molecules induced by vector beams. The interaction between the vector beam and the gas-phase molecules results in spatially varying polarizability, imparting a phase modulation to a probe laser. This process effectively creates a tunable ``molecular waveplate'' that adapts naturally to a broad spectral range. By leveraging this approach, we can generate ultrashort vortex pulses across a wide range of wavelengths. Under optimized gas pressure and interaction length conditions, this method allows for highly efficient conversion of circularly polarized light into the desired OAM pulse, thus enabling the generation of few-cycle, high-intensity vortex beams. This molecular waveplate, which overcomes the limitations imposed by conventional optical elements, opens up new possibilities for exploring strong-field physics, ultrafast science, and other applications that require high-intensity vortex beams.