Broader than ever

Nature Commun. 3, 807 (2012)

Jens Biegert and co-workers from Spain, the UK and France have developed a high-energy-density supercontinuum that spans 3.3 octaves from the blue to the mid-infrared. The researchers made their supercontinuum by focusing femtosecond-duration mid-infrared pulses into a 2-mm-thick YAG crystal. Filamentation of the pulses resulted in a supercontinuum with a spectrum spanning 450–4,500 nm — allegedly the broadest ever produced by filamentation in a bulk material. The supercontinuum also featured good shot-to-shot reproducibility and a spectral energy density of between 2 pJ nm⁻¹ and 10 nJ nm⁻¹, making it amenable for practical applications that require an intense broadband light source. The researchers say that the generation process preserves the carrier-to-envelope phase and that the smooth nature of the spectrum indicates the absence of complex pulse-splitting.