Tamer H. Coskun

Observation of incoherently coupled photorefractive spatial soliton pairs.

We report what is to our knowledge the first observation of incoherently coupled photorefractive spatial soliton pairs.

Modulation Instability of Incoherent Beams in Non-Instantaneous Nonlinear Media

We show that modulation instability can exist with partially spatially incoherent light beams in a noninstantaneous nonlinear environment. For such incoherent modulation instability to occur, the value of the nonlinearity has to exceed a threshold imposed by the degree of spatial coherence.

Incoherently coupled dark–bright photorefractive solitons

We report the observation of incoherently coupled dark-bright spatial soliton pairs in a biased bulk photorefractive crystal. When such a pair is decoupled, the dark component evolves into a triplet structure, whereas the bright one decays into a self-defocusing beam.

Incoherent spatial solitons in saturable nonlinear media

It is shown that partially incoherent spatial solitons are possible in saturable nonlinear media. This is demonstrated by means of an exact Gaussian solution in the case when the saturable nonlinearity is of the logarithmic type. The conditions necessary to establish these soliton states as well as their associated characteristics are discussed in detail. Pertinent examples are provided to elucidate their behavior further.

Dynamics of incoherent bright and dark self-trapped beams and their coherence properties in photorefractive crystals

Using the coherent density approach, we study the propagation dynamics of incoherent bright and dark beams in biased photorefractive crystals. We show that, under appropriate initial conditions, bright as well as darklike incoherent quasi-solitons can be established in this material system. Our numerical simulations demonstrate that the coherence properties of these beams can be significantly affected by the self-trapping process.

Incoherent collisions between one-dimensional steady-state photorefractive screening solitons

We report the observation of collisions between mutually incoherent, one‐dimensional, bright, steady‐state photorefractive screening solitons. Using the theory of planar dielectric waveguides together with the theory of photorefractive screening solitons, we explain how the collisions depend on the peak intensity of the solitons and the externally applied biased field. Finally, we compare the experimental results with direct numerical simulations.

Diffraction-free planar beams in unbiased photorefractive media

We show that a new class of nondiffracting planar beams is possible in unbiased photorefractive media.

Coherence enhancement of spatially incoherent light beams through soliton interactions.

We show that the spatial coherence of a partially incoherent light beam can be greatly enhanced through an energy-conserving interaction with an incoherent or a coherent dark spatial soliton. Computer simulations show that during this process a portion of the incoherent beam is trapped within the dark notch of the dark soliton, thus forming a sharp intensity spike. In this region the correlation length dramatically increases by at least 2 orders of magnitude.

Self-bouncing optical beams in photorefractive waveguides

It is shown that, as a result of diffusion space-charge field effects, self-bouncing beam behavior is possible in photorefractive waveguides. The process is explicitly demonstrated by means of an exact Gaussian solution in the case of parabolic planar waveguides. The trajectory of these beams as well as their associated characteristics is given in terms of relevant parameters. Asymmetric modal states are also obtained for parabolic and other waveguide structures.

Dark incoherent soliton Y-splitting: experiment and theory

Summary form only given. Incoherent Y-splitting was first predicted by using the coherent density approach. We report the first experimental observation of dark incoherent soliton Y-splitting in a Strontium Barium Niobate (SBN) photorefractive crystal. The evolution of these incoherent soliton doublets is then systematically investigated as a function of their coherence, both experimentally and theoretically.