Dai Jian-hua

A BISTABLE LIQUID CRYSTAL ELECTRO-OPTIC MODULATOR

Abstract A new liquid crystal hybrid bistable optical device is described. Optical bistability has been observed and the use of this device for optical logic elements and ultralinear modulation applications demonstrated. The transient response of the device for optical logic elements and ultralinear modulation applications demonstrated. The transient response of the device has also been studied and a “critical slowing down” phenomenon observed.

Analytical study of a bimodal mapping related to a hybrid optical bistable device using liquid crystal

We suggest a method to determine analytically the parameter values of all superstable periods and the equations of dark lines seen in various bifurcation diagrams, plotted for a bimodal mapping related to a hybrid optical bistable device in which liquid crystal was used as the nonlinear medium.

Analytical Study of a Bimodal Map Related to Optical Bistability

Using an analytical method proposed originally for the logistic map, we studied in detail the bifurcation diagram of a bimodal map related to a hybrid optical bistability device with liquid crystal as the nonlinear medium. In particular, we gave the equations of all the dark lines going through the chaotic region and all boundaries of the chaotic bands. We showed how to determine the parameter value for a given superstable period from corresponding word in the symbolic dynamics made of four letters.

TRANSIENT OPTICAL VORTICES IN THE PROCESS OF PATTERN FORMATION IN A KERR SLICE SYSTEM WITH SINGLE FEEDBACK

The transient process of the optical pattern formation in a Kerr medium is numerically studied. We find that the process is accompanied by transient optical vortices in the far field. The temporal evolutions of the appearance and disappearance of the vortices are presented. All vortices will vanish when the system approaches its steady state. The number of vortices versus time is given.

Optical bistability in a ring cavity with a photorefractive two-wave mixer

We observed the phenomenon of optical bistability in a ring cavity with a photorefractive two-wave mixer. The experimental results are in agreement with those of theory.

Transverse Modulation of a Laser Beam in Cerium-Doped BaTiO3

An extraordinarily polarized Gaussian beam, after passing through a photorefractive crystal with an external electric field, shows transverse spatial modulation and self-focusing due to the in-phase component of the refractive index change relative to the intensity profile of the beam. Besides that the beam shifts toward the crystal c-axis due to the π/2 out-of-phase component.

A theoretical and experimental study of frequency redshift in optical-field-induced Freedericksz transition in a nematic liquid crystal film

The frequency redshift in the optical-field-induced Freedericksz transition in a nematic liquid crystal film is investigated. We derive a theoretical expression for the frequency shift, and then measure the temporal evolution of the frequency shift and the light-intensity dependence of the maximum frequency shift. The theory agrees with the measurements.

A continuous compound four-wave mixing mechanism for self-pumped phase conjugation in BaTiO3 crystals

A continuous compound four-wave mixing mechanism for self-pumped phase conjugation in photorefractive crystals is presented. The coupled-beam equations of this mechanism are solved numerically when depletion of the forward going beam is neglected. The experiment in a Ce-doped BaTiO3 crystal is performed, with the stable phase conjugate reflectivity of as much as ≥ 80%. The curved high output phase conjugate intensity are explained using the numerical results.

TRANSIENT BEHAVIOR OF THE SELF-PUMPED PHASE CONJUGATE BEAM BY THE CHANGE OF INCIDENT BEAM INTENSITY

We have studied the transient behavior of the self-pumped phase conjugation when the incident beam is below the saturation intensity. We found that, when the incident beam intensity is changed abruptly, the intensity of the conjugate beam always decreases at first and then gradually increases to its stable value. This is due to the fact that the positions of the two coupled interaction regions are changed.

Multigrating nondegenerate oscillation and phase shift in the linear SPPCM

The nondegenerate four-wave mixing in a linear self-pumped phase-conjugate mirror with arbitrary-chosen complex coupling constants has been studied by numerical methods. The frequency detuning and the phase-conjugate reflectivity versus cavity path length detuning for different complex coupling constants are discussed in detail. It is found that multigrating operation in some cases can enlarge the interval of cavity path length detuning to be compensated for by frequency detuning and improve the phase-conjugate beam generation. The phase relation between the output phase-conjugate beam and the input beam is calculated and the result is in agreement with the experimental results.