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arXiv · 2606.11811

Multi-pulse accumulation of gas molecular coherence enables gigahertz ultrafast frequency conversion

Yazhou Wang·Marcello Meneghetti·Ian Davidson·Timothy Bate·J. E. Antonio-Lopez·Qiang Fu·Jaroslaw Rzegocki·Gregory T. Jasion·Rodrigo Amezcua-Correa·Francesco Poletti·Christos Markos
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Abstract

Frequency conversion of ultrafast lasers is fundamentally constrained by the trade-off between pulse energy and repetition rate, limiting access to regimes critical for fundamental science and industry. Here, we demonstrate a frequency-conversion mechanism in which molecular coherence accumulates across ultrafast pulse trains in gas-filled hollow-core fibers. Unlike conventional nonlinear interactions initiated by individual high-energy pulses, this mechanism relies on the collective buildup of coherent molecular oscillations driven by successive pulses. Using this mechanism, we achieve Raman frequency conversion at repetition rates up to 3 GHz with nanojoule pulse energies. The results establish a regime of nonlinear optical interaction governed by coherence accumulation of gas molecular oscillations with broad implications for ultrafast laser science and frequency conversion technologies.

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Yazhou Wang, Marcello Meneghetti, Ian Davidson, Timothy Bate, J. E. Antonio-Lopez, Qiang Fu, Jaroslaw Rzegocki, Gregory T. Jasion, Rodrigo Amezcua-Correa, Francesco Poletti, Christos Markos. 2026-06-10. Multi-pulse accumulation of gas molecular coherence enables gigahertz ultrafast frequency conversion. https://arxiv.org/abs/2606.11811

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