Generation of wide-band optical continuum in fiber waveguides

Excitation of multimode phosphosilicate fiber waveguides with pulses of 0.53 and 1.06 μ wavelengths gave rise to the Stokes components of the stimulated Raman scattering as well as to an anomalously wide continuous emission spectrum extending from ultraviolet to near infrared. The observed effects were explained by four-photon parametric processes. Absorption lines attributed to inverse Raman scattering were observed in the anti-Stokes part of the spectrum.