Tuning of the frequency of laser radiation with the aid of stimulated four-photon processes in germanium oxide-silicate fiber waveguides subjected to biharmonic pumping

An investigation was made of the tuning of the Stokes and anti-Stokes components of stimulated four-photon processes in germanium dioxide-silicate fiber waveguides when the wavelength of one of the biharmonic pumping waves and the core radius were altered. An analysis was made of the propagation of the components formed by such four-photon processes in various combinations of the first two LP waveguide modes. The ranges of the waveguide parameters and pump wavelengths satisfying the condition of phase matching of the modes participating in the stimulated four-photon processes were determined. Feasibility of phase matching in single-mode waveguides at pump wavelengths very different from the wavelength at the maximum of the material dispersion was demonstrated. Variation of the wavelength of one of the pump waves within intervals typical of tunable lasers varied the wavelengths of the Stokes and anti-Stokes components of the investigated four-photon processes in wide spectral ranges in the visible and near infrared.