Nonlinear resonant conversion of modes in optical waveguides

Abstract

A new class of resonant exchange of power among three co-propagating modes in dielectric optical waveguides exhibiting Kerr-like nonlinearity is reported. Unlike the coupling of modes travelling in different, spatially separated channels as in the directional coupler (Jensen, IEEE J. Quantum Electron. QE-18 ( 1982) 1580; Chen, Snyder and Mitchell, Electron. Lett. 26 ( 1990) 77; Schmidt-Hattenberger, Trutschel and Lederer, Optics L&t. 16 (1991) 294) this paper points out the possibility of obtaining an efficient coupling of modes travelling in one single channel. 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 propagation constants, the power exchange process is very sensitive to the wavelength.

Mode conversion in nonlinear waveguides stimulated by the longitudinal bi-harmonic refractive index modulation

“…In practice, optical revivals (or stimulated mode conversion) have been realized in optical fibers, subjected to periodic mechanical stress, and in long-period photoinduced gratings [9][10][11][12]. Conversion of guided modes, stimulated by shallow longitudinal refractive index modulations, was predicted in multimode waveguides [13] and demonstrated experimentally in photonic lattices [14].…”