NONLINEAR RESONANT CONVERSION OF MODES IN OPTICAL WAVE-GUIDES

A new class of resonant exchange of power among three co-propagating m odes in dielectric optical waveguides exhibiting Ken-like nonlinearity is reported. Unlike the coupling of modes travelling in different, sp atially separated channels as in the directional coupler (Jensen, IEEE J. Quantum Electron. QE-18 (1982) 1580; Chen, Snyder and Mitchell, El ectron. Lett. 26 (1990) 77; Schmidt-Hattenberger, Trutschel and Ledere r, Optics Lett. 16 (1991) 294) this paper points out the possibility o f obtaining an efficient coupling of modes travelling in one single ch annel. The key point here is the imposition of a geometrical resonance between modes, to improve the coupling process. Due to this resonance condition, which is related with the wavelength through the propagati on constants, the power exchange process is very sensitive to the wave length.