Photorefractive spatial solitons, induced waveguides, and their applications

This thesis presents theoretical and experimental research on optical spatial solitons and their waveguides. Different applications are proposed and demonstrated.; It is shown for the first time that, soliton-induced waveguides can be used to build optical directional couplers. By generating two mutually incoherent parallel solitons at close proximity, efficient energy transfer of a probe beam from one induced waveguide to another is observed, and the efficiency is studied as a function of the distance between the two solitons.; Two important applications of soliton-induced waveguides in frequency conversion are proposed and demonstrated: second harmonic generation and optical parametric oscillation. It is shown that with soliton-induced waveguides, the conversion efficiency of second harmonic generation can be greatly improved, and the pump threshold of optical parametric oscillators can be noticeably reduced. In addition to enhanced efficiency conversion, soliton-induced waveguides offer more advantages, such as tunability. Angle tuning and electrical tuning methods are investigated.; It is also proposed that optical gratings can be built by launching two coherent counter-propagating spatial solitons. The study of the mutual self-trapping of such two solitons leads to a new concept of vector solitons-counter-propagating solitons. The theories and experimental results of this new vector soliton are presented, and the reflection from the grating is observed.; Two other topics of vector solitons are also investigated. (1) Theoretical and experimental results show that the collision between two vector solitons can offer a feather that is not existent with scalar solitons: energy exchange. (2) (2+1)D multimode solitons are demonstrated for the first time.