Three-Dimensional All-Optical Switching Using a Single Diffracting Bessel Beam

A single Bessel beam (BB) enables the scalable optical writing of waveguide devices with multiple inputs and outputs in a nonlinear medium. For this purpose, we experimentally propagate a diffracting zero-order BB in a strontium barium niobate photorefractive crystal. Such a configuration can be used for the self-writing of complex waveguiding structures. By tailoring different key parameters such as the diffraction phenomenon through the BB size, the nonlinearity strength through the applied electric field, and the photoinduced refractive-index modulation depth through input beam intensity, our optical platform enables not only the generation of optical splitters but also an all-optical control of the output intensity levels. We also analyze the stability in space and time of the different photoinduced channels. We show that adding a background illumination onto the medium permits a steady-state photoinduced refractive-index modulation with up to nine output channels. These results enrich the research on scalable optical writing techniques for the realization of complex interconnects and enlarge further possibilities for all-optical switching.