Abstract: A cascaded Raman laser (10) has a pump radiation source (12) emitting at a pump wavelength ?p, an input section (14) and an output section (16) made of an optical medium. Each section (14, 16) comprises wavelength selectors (141, 142, . . . , 145 and 161, 162, . . . , 165) for wavelengths ?1, ?2, . . . , ?n?k, where n?3, ?p<?1<?2< . . . <?n?1<?n and ?n?k+1, ?n?k+2, . . . , ?n being k?1 emitting wavelengths of the laser (10). The laser further comprises an intracavity section (18) that is made of a non-linear optical medium, has a zero-dispersion wavelength ?0 and is disposed between the input (14) and the output (16) section. The wavelengths ?1, ?2, . . . , ?n?k of the wavelength selectors (141, 142, . . . , 145 and 161, 162, . . . , 165) and the zero-dispersion wavelength ?0 of the intracavity section (18) are chosen such that energy is transferred between different wavelengths by multi-wave mixing.