Since the 1980s, dispersive waves have been studied in the concept of solitons (waves that maintain their shape while traveling at constant speeds). Now, a research team led by Fetah Benabid, University of Bath, has observed for the first time the simultaneous emission of two resonant dispersive waves by optical solitons. By designing a special fiber with an extremely small waveguiding feature located in the photonic crystal fiber cladding, the researchers were able to bring the theoretical prediction into the experimental demonstration, creating waves on both sides of the pump. Because of the flexibility in the unique design of Benabid's fiber, which is a nanometric-sized, rectangular-shaped waveguiding feature located in the photonic crystal fiber cladding, the waves are more general than they have been in the past. These "general" waves allow for a further degree of control over supercontinuum generation and have enabled a new way of generating coherent supercontinuum spectra, which is useful in a number of applications such as frequency combs. In addition, the tight confinement along with the particular dispersion properties allow supercontinuum to be generated very efficiently and over very short length, creating the potential for very compact femtosecond lasers. This research appears in the current issue of the Optical Society's Optics Letters.For more information, visit: www.osa.org