Second-Harmonic Generation in Optical Fibres Induced by a Cross-Phase Modulation Effect

When two optical pulses copropagate inside a single-mode fibre, intensity-dependent refractive index couples the pulses through a cross-phase modulation (XPM). We show that a second-harmonic generation (SHG) on a continuous-wave background is possible in the optical fibre induced by the XPM effect. By means of a multi-scale method the nonlinearly coupled envelope equations for the SHG are derived and their explicit solutions are provided and discussed.