Ultra-high repetition rate absorption spectroscopy with low noise supercontinuum radiation generated in an all-normal dispersion fibre

We report the use of a dispersed supercontinuum generated in an all-normal-dispersion fibre to record low-noise spectra from atmospheric molecules at least an order of magnitude faster than has been previously reported. Supercontinuum generation in standard, anomalous dispersion photonic-crystal fibres is inherently connected with large pulse-to-pulse fluctuations resulting in detrimental consequences for high resolution spectroscopy if temporal averaging is not permitted. Replacing the standard photonic-crystal fibre (PCF) with a specially designed all-normal dispersion PCF we find that a substantially superior noise performance is achieved and present its use for high repetition rate absorption spectroscopy where spectra covering hundreds of nm in spectral bandwidth can be captured of gases at hundreds of kHz repetition rates. (letter)