Abstract

Photorefractive spatial solitons and their induced waveguides¹ have been of great interest in recent years because of their dimensionality, wavelength sensitivity, and fixability. With these properties, they offer potential applications,^2,3 such as: reconfigurable near-field optical interconnects, three-dimensional optical circuitry,⁴ directional coupling,^5,6 beam steering,⁷ and frequency conversion. Among them the most promising is nonlinear frequency conversion. The conversion efficiency in χ⁽²⁾processes is proportional to the intensity of the pump beam and can be improved by focusing. However, in bulk, diffraction limits the conversion efficiency because as the beam diffracts, (1) the intensity decreases, and (2) the phase-matching condition cannot be satisfied across the entire beam. Therefore, using waveguides for frequency conversion can greatly improve the conversion efficiency. Waveguides induced by photorefractive solitons not only increase the conversion efficiency but also offer flexibility, because the waveguide structure can be modified at will. For example, waveguides induced by photorefractive solitons offer broad tunability: wavelength tunability in frequency conversion is achieved by rotating the crystal and launching a soliton in the new direction, or by changing the propagation constants of the guided modes by varying the intensity ratio and external voltage (without mechanical movement)

© 2002 Optical Society of America