A group at the University of Bath in the UK and at Los Alamos National Laboratory in New Mexico has presented numerical simulations and experimental findings that show that controlling the chromatic dispersion profile of photonic crystal fibers enables the generation of coherent radiation at novel wavelengths. It published the results of its study in the July 31 issue of Nature.The team measured the output intensity spectra from photonic crystal fibers with flattened chromatic dispersion profiles of 17 to –7 ps nm-1 km-1 that were pumped with 100-fs pulses of 1550-nm radiation from a Ti:sapphire laser. The observed output spectra were very sensitive to the dispersion of the fiber.The close agreement of the results to numerical solutions of the generalized nonlinear Schrödinger equation for the fibers indicates that the underlying processes may be reliably modeled. The effects may be exploited for optical coherence tomography, frequency metrology, wavelength conversion and other applications in nonlinear laser science.