Experimental signatures of dispersive waves emitted during soliton collisions.

We report experimental evidence of dispersive waves with enhanced redshift generated through soliton collisions in a photonic crystal fiber with two zero-dispersion wavelengths. Experiments are performed to study both controlled collisions under twin-pulse excitation, as well as spontaneous collisions arising from noise-induced supercontinuum generation. Experimental results for the spectral and statistical properties are in good agreement with numerical simulations and are shown to be associated with extreme-value like distributions with long tails.