Ultrashort visible light pulses made easy

https://physicsworld.com/a/ultrashort-visible-light-pulses-made-easy/

"Using an industrial-grade ytterbium laser system, they began by propagating a much longer (175 fs) infrared pulse centred at a wavelength of 1035 nm through a 3-m-long hollow-core fibre filled with argon gas at a pressure of about 3 bar. As the different modes mixed with each other, a nonlinear effect within the gas generated intense, 4.6-fs-long pulses of visible light at the fibre output"