To date, supercontinuum light in the visible and near-infrared ranges is readily realizable by the optical Kerr effect through self-phase modulation of ultrashort laser pulses in transparent media. However, it is still a challenge to extend the supercontinuum spectrum down to the deep-ultraviolet (DUV) range, which is particularly needed for exploring ultrafast dynamics in chemistry, materials, and biology. Here, an approach of non-resonant coherent Raman scattering is developed to generate ultra-broadband visible-DUV supercontinuum in ambient air with a spectral range spanning over 250 nm and a wavelength down to 220 nm. A rovibrational coherence is established in air molecules by filamentation of a near-infrared femtosecond 800 nm pulse and two femtosecond Raman laser pulses at 267 and 400 nm are introduced into the coherent media to induce non-resonant coherent Stokes and anti-Stokes Raman scatterings, which serve as the spectral bridges to link the neighboring Raman pump laser spectra, resulting in ultra-broadband supercontinuum light. The mechanism is further verified by examining the broadening of picosecond N₂⁺ laser lines with narrow bandwidths (10–30 cm⁻¹), which forms a supercontinuum spectrum spanning over 150 nm. The work provides a viable route for the establishment of coherent DUV supercontinuum in the gas media at designed wavelength ranges.

中文翻译：

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通过空气中的非共振相干拉曼散射产生超宽带可见光-DUV 超连续谱


迄今为止，可见光和近红外范围内的超连续光很容易通过光学克尔效应通过透明介质中超短激光脉冲的自相位调制来实现。然而，将超连续谱扩展到深紫外 （DUV） 范围仍然是一个挑战，这对于探索化学、材料和生物学中的超快动力学尤其需要。在这里，开发了一种非共振相干拉曼散射方法，在环境空气中产生超宽带可见光-DUV 超连续谱，光谱范围超过 250 nm，波长低至 220 nm。通过近红外飞秒 800 nm 脉冲的细丝化，在空气分子中建立振动相干性，并将 267 nm 和 400 nm 的两个飞秒拉曼激光脉冲引入相干介质中，以诱导非谐振相干斯托克斯和反斯托克斯拉曼散射，它们作为连接相邻拉曼泵浦光谱的光谱桥。 产生超宽带超连续谱光。通过检查具有窄带宽 （10-30 cm ⁻¹ ） 的皮秒 N ₂ ⁺ 激光线的展宽，进一步验证了该机制，从而形成跨越 150 nm 的超连续谱。这项工作为在设计波长范围内的气体介质中建立相干 DUV 超连续谱提供了一条可行的途径。