Intense visible white-light pulse generation in gas-filled hollow-core fibers pumped by Yb-lasers for multi-color time-resolved spectroscopy

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Ultrashort, high-energy laser pulses have delivered unprecedented capabilities in driving and probing ultrafast dynamics in various materials and nowadays represent the cornerstone of a multitude of research fields in modern science. However, despite the three decades of progress of laser frequency conversion and amplification technology, the generation of energetic few-cycle visible white light (VIS-WL) pulses (wavelength: 400-800 nm) is still very challenging. Such pulses are regarded as an essential tool for the temporal investigation of e.g., biological energy transfer processes and photo-generated charge carrier dynamics in semiconductors. Current technology typically requires extremely complex alignment and apparatus that lower the conversion efficiency and deteriorate the beam quality. Also, the maximum achievable pulse energy is limited in such systems, due to the damage threshold of the employed nonlinear crystals. In this context, gas-filled hollow-core fibers (HCF) represent an appealing alternative nonlinear platform, as they accommodate high-energy pulses and provide a straightforward spectral extension, together with excellent output beam characteristics. Prof. Razzari's group at INRS-EMT has recently obtained a promising preliminary result of ultrafast VIS-WL pulse formation in an HCF pumped by ytterbium (Yb) laser pulses. The thorough investigation of this novel VIS-WL generation mechanism in an HCF and its exploitation into a marketable setup are the key target of this project. To achieve these goals, an overall team of 1 PhD student and 2 postdocs, helped by 2 intern students every year, will work on the project full time. These personnel will be supervised by Prof. Razzari and will closely interact with our industrial partner (few-cycle Inc.). Eventually, our partner company will be able to introduce an affordable and customizable multi-color system relying on an industrial-grade Yb laser to study the response of a variety of materials on ultrafast time-scales, thus allowing a large number of academic and industrial labs to have access to a technology currently available only in a handful of top-notch research centers around the world.