Ye Peixian

Observation of Optical Bistabilities in a Doped Polymer Thin Film Quasi-waveguide

Optical bistability was observed and studied in the output of reflected beam as well as in that of m-lines in a doped polymer thin film quasi-waveguide. The physical origin was demonstrated to be the existence of a mode spectrum and the high third-order nonlinearity of the polymer film. It was also observed for the first time that the intensity variation of the reflected beam and the m-line in the hysteresis loops are complementary to each other.

Observation of Optical Bistability Hysteresis Loop with Surface Waves in Doped Polymer Film

Optical bistability hysteresis loop has been observed experimentally with a setup using prism excitation of surface wave in a doped polymer thin film. A simple model has been developed to analyze its operation. The observed bistability hysteresis loop can be explained in terms of surface plasmon excitation and laser induced refractive index variations.

New organic system for photon-gated persistent spectral hole burning

We report a new system of organic materials for photon-gated persistent spectral hole burning by donor-acceptor electron transfer: a tetrabenzoporphyrin derivative as donor and one of several aromatic cyanides as an acceptor in a poly (methyl methacrylate) (PMMA) host matrix. Up to 500% deep spectral holes in transmission were burnt and appeared very high hole burning efficiency.

PHOTO-INDUCED ENHANCEMENT OF THE THIRD-ORDER OPTICAL NONLINEARITY IN AZOBENZENE COMPOUND ON THE PICOSECOND TIME SCALE

Photo-induced enhancement processes of the third-order optical nonlinearity were observed in azobenzene solution under a 30ps pulse pumping at 532 nm. Weinvestigated the time evolution of the enhancement and found that it was mainly due to the population of the first excited state. By theoretical simulation of the enhancement processes, the values of the hyperpolarizabilities of the sample-molecules at ground state and at excited state, γg and γs1, were determined to be 1.11 × 10-33 esu and 7.40 × 10-33 esu, respectively.

TEMPORAL CHARACTERISTICS OF DECAY OF LIGHT-INDUCED ABSORPTION IN PHOTOREFRACTIVE BaTiO 3 CRYSTALS

We report the observations of the decay processes of light-induced absorption in one undoped and two Ce-doped BaTiO3 crystals. Two decay times were found, they had not a strong dependence on intensity in our experiment. We present a model with two different shallow trap centers to explain the experimental results. The theoretical and experimental results agree well with each other. The light-induced absorption coefficients and decay times corresponding to the two shallow levels are also given.

Theoretical studies on laser-induced gratings in organic photoisomers

A theoretical model for formation of light-induced gratings in organic photoisomers is presented. Using this model, dynamic behaviors of the light-induced gratings are studied theoretically for two different cases: in the first case, in addition to a CW laser generating the writing beams and the reading beam, a pulsed laser is used as an optical pump, in the second case, the writing beams are provided by a pulsed laser, and the reading beam comes from a CW laser. Agreement between experiment and theory is also demonstrated.

Competition between self-pumped and mutually-pumped phase conjugations in a BaTiO3 bridge phase conjugator

This paper reveals the inter-dependence and the competition between self-pumped and mutually-pumped phase conjugations, and deals with the periodic instabilities in the phase conjugate output of a BaTiO3 bridge phase conjugator. It presents experimental data demonstrating these instabilities and also gives evidence that the addition of the second beam in a bridge phase conjugator can affect the self-pumping threshold for the first beam. A mathematical model is developed to explain the observed output oscillations.

Simulating study on internal self-pumped phase conjugators with external configurations

A new method is proposed to study the properties of stimulated photorefractive backscattering and four-wave-mixing (SPB-FWM) and total-internal-reflection (TIR) self-pumped phase conjugators. The phase conjugators are simulated with external configurations using a KNSBN:Cu crystal, a plane mirror and a prism. As a result, the parameters such as beamwidth and intensity of the contra-directionally propagating pump beams for the FWM interactions in the crystal can be easily controlled. The dependence of self-pumped phase conjugation reflectivity and FWM coupling strength on these parameters of the pump beams have been studied.

Broadband Fluorescence Guided-Wave in DANS/PMMA Thin Film Waveguides

The broadband fluorescence guided-waves excited in DANS/PMMA polymer thin film waveguides by an Ar+ laser beam were demonstrated in terms of the observation of mlines with colour array. Considering the high brightness of these m-lines observation, we assert that it is a kind of stimulated amplification of fluorescence guided-wave.

Light-induced absorption enhancement in C60 toluene solution

Absorption enhancement induced by a pump beam of 532 nm in C60 toluene solution has been observed and studied from 560 nm to 630 nm, and the absorption cross section of its lowest triplet state has been determined in this wavelength range according to our theoretical model.