Highly efficient Cherenkov radiation in photonic crystal fibers for broadband visible wavelength generation.

We investigate the dependence of Cherenkov radiation (CR) on pump pulse parameters and its evolution along the propagation distance. Using a Ti:sapphire laser emitting 10 fs pulses as the pump source, we demonstrate highly efficient (>40%), broadband (>50 nm) CR in the visible-wavelength range with a threshold energy less than 100 pJ and a tuning range over 100 nm.