Light-induced Photonic Lattices, Vortex Of Light Propagation Characteristics Of Study

Optical vortices are intriguing special optical structures with helical wave fronts, which attract much attention for their well-defined orbital angular momentum properties. This kind of special optical field has been applied in many fields that include optical micromanipulation, atomic optics, biology, and quantum information processing. In nonlinear optics, optical vortex is stable and can self-trap into a dark vortex soliton in self-defocusing nonlinear materials. However, It will break up into fundamental solitons in self-focusing nonlinearity due to the azimuthally modulation instability. Until recently, people find that optical vortex can keep its helical phase structure in optically induced photonic lattices even in self-focusing nonlinearity, which opens a new area for studying the properties of vortices.On the other hand, photonic lattice is a kind of periodic refractive index micro-structure. It has band gap structure, where in the gap the propagation mode is forbidden. Optical waves propagation in linear and nonlinear periodic photonic structures exhibit behavior characteristic of that encountered in discrete systems, which in many cases has no counterparts in homogeneous systems. These distinct features of discreteness can be exploited for potentially important application in all-optical signal and data processing, optical communication systems and switching networks.Optical vortex propagation in photonic lattice is dominated by discrete effect, nonlinearity and its angular momentum. Many new phenomena and effects are expected. Our results may prove to be relevant to studies of similar vortex phenomena in other periodic systems beyond optics. In this dissertation, we studied the properties of vortex beam propagation both inside and at the surface of 2D optically induced photonic lattices. The contents of this dissertation are outlined as follows:Firstly, we investigate optical vortices propagation in 2D optically induced photonic lattice with self-focusing nonlinearity. We predict and experimentally observe single-charged gap vortex solitons which bifurcating from the top of the second band. Double-charged gap vortex soliton are also predicted. Two dimensional multiband vector solitons are experimentally demonstrated. Different from their counterpart in homogenous medium, these kind of solitons consist of two optical fields arising from different bands of the transmission spectrum. Optical vortex beam propagation in photonic lattice with a negative defect is also numerically investigated. Our results may pave a way for experimental observation of such high order defect mode.Secondly, we experimentally and theoretically study both single-charged and double-charged optical vortices propagation in 2D optically induced photonic lattice with self-defocusing nonlinearity. We experimentally observe single-charged gap vortex solitons . Spectrum measurement and numerical analysis suggest that the gap vortex soliton does not bifurcate from the edge of the Bloch band, quite different from previously observed gap spatial solitons. Both quadruple gap solitons and Double-charged gap vortex solitons are also demonstrated. They both can be realized by a donut-shaped double-charged vortex under different excitation.Lastly, we experimentally and numerically study vortex beam propagation at the interface between optically induced photonic lattice and homogenous medium. We find a new kind of nonlinear discrete surface wave which carries angular momentum can exist at the boundary of the optically induced waveguide arrays.