Power Transfer in Multiport Waveguide Devices Made from Solitons

Abstract

Light-guiding-light phenomena [1] suggest a number of applications in all-optical information processing. One of the most interesting effects is the ability of the spatial soliton, created by a strong beam inducing a sech-type refractive index profile, to behave as a waveguide, carrying a weak probe beam [2]. These waveguides can be made either with bright [2] or dark [3] spatial solitons. Such facts suggest further that colliding solitons might serve as X-junctions [5,6] and more generally as multiport devices. Several such devices have been analyzed to date [6,7]. The use of a probe beam with the same frequency as the pump is preferable because these devices then have no losses in the impact area of two solitons [6]. Moreover, a probe beam injected into one of the channels has no reflected component in this case. It passes through the impact area of the soliton collision and is distributed totally among the output channels. This is one of the essential properties of any ideal NxN switch. On the other hand, the use of a probe beam of the same frequency introduces the problem of its separation from the pump. Thus, from the experimental point of view it is more convenient to use a weak probe beam at different frequency [7], in which case the probe can be separated from the pump simply by spectral filtering. However, in this case “solitonic” devices like X-junctions or NxN switches lose their beauty because of losses in the soliton collision area [7] and the fact that an input beam can potentially be reflected into any of the input channels.