Abstract
We present, for the first time a theoretical foundation for separately coupled solitons in a biased series circuit consisting of semi-insulating photorefractive multiple quantum well (MQW) waveguides. As an example, a slab semiconductor waveguide based on a GaAs/AlGaAs structure is considered. The coupled steady state space charge field is derived for both the MQW structures using a bipolar band transport model. Hence, a system of two coupled equations is obtained for each MQW structure which governs the dynamical evolution of light beams. We then prove the existence of dark-dark, grey-grey and grey-dark separately coupled soliton pairs. We also see that the soliton propagating individually in one PR semiconductor can affect the other by the light-induced current. We investigate this coupling effect with respect to the soliton beam's intensity profile and for each of the three cases, namely, dark-dark, grey-grey and grey-dark separately coupled solitons. Some potential applications are discussed.