Jinsong Liu

Observation of two-dimensional holographic photovoltaic bright solitons in a photorefractive-photovoltaic crystal

Two-dimensional holographic photovoltaic bright spatial solitons are observed in a Cu:K0.25Na0.75Sr1.5Ba0.5Nb5O15 crystal in which two coherent laser beams, a signal beam, as well as a strong and uniform pump beam at 532nm are coupled to each other via two-wave mixing. Such solitons originate from the self-trapping of the signal beam due to both photovoltaic effects and holographic focusing effects.

Theoretical investigation on the threshold properties of localized modes in two-dimensional random media

We present a detailed calculation to analyse the threshold properties of individual localized modes in two-dimensional random media. Some long- and short-life localized modes are selected and indicated from the spectral intensity of a passive system. By pumping the system, the pumping rate dependence of the peak intensity of the indicated modes is obtained. Results identify that these modes have a typical threshold gain behaviour, and the pumping thresholds of long-life modes are lower than those of short-life modes. By calculating the energy decay rate, the lifetime is obtained for each mode, and the results show that there exists a certain correspondence between the mode threshold and lifetime and that, the longer the lifetime, the lower the threshold is.

Self-deflection of screening-photovoltaic spatial solitons in biased photovoltaic photorefractive crystals

Abstract The self-deflection of a solitary wave arising from diffusion effects in a biased photovoltaic photorefractive crystal has been systema

Self-focusing effects in an organic photorefractive film without a biased field

We report the observation of self-focusing effects in organic photorefractive films based on a carbazole derivative and sensitizer 2,4,7-trinitro-9-fluorenone at 632.8 nm wavelength without applying a biased field, owing to the orientationally enhanced photorefractive nonlinearity caused by photopolymerization of the carbazole derivative. The experiment was repeated in three samples with different sensitizer doping percentages and similar phenomena were observed.

Self-deflection of dissipative holographic screening-photovoltaic solitons in a biased dissipative photovoltaic-photorefractive crystal

The self-deflection of dissipative holographic screening-photovoltaic (DHSP) solitons has been investigated in the dissipative system, which consists of a biased dissipative photovoltaic-photorefractive (PV-PR) crystal and two coherently coupled beams; the signal beam (self-trapping beam) gets the energy gain from the pump beam via the two-beam coupling process. The analytical results are in good agreement with the numerical ones. Both predict that the centre of the solitary beam moves on a parabolic trajectory. Moreover, the central spatial-frequency component shifts linearly with the propagation distance. The DHSP soliton has the fixed self-deflection that is completely determined by the system parameters, its self-deflection is slight under small-signal condition, which will bring little influence on the formation of DHSP solitons. Furthermore, the relevant properties on the behaviour of bright DHSP soliton are discussed in detail.

Observation of holographic photovoltaic solitons in an organic glass without an external field

We report the observation of holographic photovoltaic solitons in a carbazole photorefractive material without an external field, owing to an asymmetric energy transfer in the two-beam coupling process in the material. The sample is prepared from the mixture of chromophore 3-Formyl-N-vinylcarbazole (99.9 wt%) and sensitizer 2,4,7-trinitro-9-fluorenone (0.1 wt%).

Transformation properties of an indefinite media slab for paraxial beams

On the basis of paraxial beam propagation theory in indefinite media, the effective refraction index for both of the two types of polarized electromagnetic wave, TE and TM waves, are introduced. According to the definition of effective refraction index, we obtain the conditions that paraxial beams pass through the indefinite media. We propose to employ a slab of indefinite media to construct a polarizer or polarizing beam splitter by choosing appropriate anisotropic parameters. Under certain conditions, the indefinite media slab exhibits polarization-selective focusing effect.

Effect of system parameters on evolution and stability of dark dissipative holographic screening-photovoltaic solitons in a biased dissipative system

In a dissipative photovoltaic-photorefractive (PV-PR) system, the dynamical evolution and stability of dark dissipative holographic screening-photovoltaic (DHSP) solitons are numerically investigated in this paper. A DHSP soliton is supported and determined by the given dissipative system, its stability is impacted by the system parameters, such as the linear loss of the crystal, the biasing field, the photovoltaic field, the angle between two input beams, the angle of the polarized directions and the system temperature. Such DHSP solitons can be easily amplified or absorbed by adjusting the system parameters, moreover, they are stable against small perturbation of amplitude or width.

Stability of bright screening-holographic soliton in dissipative system

We investigate the dynamical evolution and the stability of bright screening-holographic solitons, which are supported by self- and mutual cross-phase modulation, in a dissipative system. Numerical simulations reveal that such solitons are stable against small perturbation on both amplitude and width in our study. Furthermore the effect of the linear absorption of the crystal and the external bias field on the behaviour of bright screening-holographic solitons is discussed in detail.

The effects of temperature on the stability and evolution of separate photovoltaic bright–dark spatial soliton pair

The temperature effects on the evolution and stability of a separate photovoltaic bright–dark soliton pair formed in a serial photovoltaic photorefractive crystal circuit have been investigated. Our numerical results show that adjusting each crystal temperature can affect the dynamical evolution of the soliton formed in the other crystal. For a stable bright–dark soliton pair originally formed in a crystal circuit at given temperatures, when one crystal temperature changes, the soliton supported by the other crystal will evolve into another stable soliton if the temperature change is quite small, whereas it will become unstable and experience larger cycles of compression or break up into beam filaments if the temperature difference is big enough. The bright soliton and dark solitons have their own stable temperature regime.