An Yu-Ying

Properties of field quantum entropy evolution in the Jaynes-Cummings model with initial squeezed coherent states field

The properties of the field quantum entropy evolution in a system of a single-mode squeezed coherent state field interacting with a two-level atom is studied by utilizing the complete quantum theory, and we focus our attention on the discussion of the influences of field squeezing parameter γ, atomic distribution angle θ and coupling strength g between the field and the atom on the properties of the evolution of field quantum entropy. The results obtained from numerical calculation indicate that the amplitude of oscillation of field quantum entropy evolution decreases with the increasing of squeezing parameter γ, and that both atomic distribution angle θ and coupling strength g between the field and the atom can influence the periodicity of field quantum entropy evolution.

Anomalies of Doped-LiNbO3 Crystal in Photorefractive Phase Conjugation with Relation to Structural Phase Transformation

We investigate the photorefractive phase conjugation in a Ce:Fe:LiNbO3 crystal as a function of temperature (293-393 K) and find the phase conjugate reflectivity increases sharply in the vicinity of 55, 70 and 110° C. The anomalous phenomenon is possibly concerned with the structural phase transformation of a crystal, which induces an extra internal electric field to influence the phase conjugation. The value of the field is estimated at the order of 105 V/m, in agreement with the published data.

Development of 3GHz Analog Fiber Optic Link for Ultra-fast Signal Transmission

A broad bandwidth analog fiber optic link is developed for ultra-fast signal transmission under the circumstance with complicated electromagnetic fields. The electrical ultra-fast signal is converted to optical ones by electro-optic conversion method which operates via amplitude modulation mechanism. With several kilometers distance transmission, the optical signal is recovered by photo-electric conversion method correspondingly. The measurement results of the link indicate that its bandwidth is (0.0003-3)GHz, in-band flatness ±1dB, linear dynamic range 40dB, output peak-to-peak noise within 5mV, both of input and output standing-wave-ratios less than 2. Its applied in high power microwave experiments. The experimental results show that the 3GHz analog fiber optic link which employs electro-optic and photo-electric conversion techniques is suitable for ultra-fast pulse signals transmission. It greatly improves the bandwidth margin of the diagnosis system.

Time-resolved beam profiler for far-field high repetition rate pulsed laser

Measuring far-field laser beam profile is an effective way to study the atmospheric transmission effects of high power laser and analyze the laser transmission efficiency in a long distance. A laser beam profiler based on detector array is developed to measure the far-field beam absolute intensity and temporal-spatial distribution of the high repetition rate pulsed laser beam. In the experiment, the pulse width of laser is about 100ns, the repetition rate is adjustable between 1 kHz and 20 kHz, and the diameter of the far-field beam is about 20cm. The detector array is composed of 297 Si-PIN photodiode detectors with the spatial resolution of 1cm in the central region. The image of the far-field beam profile is reconstructed with the bilinear interpolation method. The beam profiler is capable for measuring far-field beam profile of high repetition rate pulsed laser, with response wavelength between 400nm and 1100nm, minimal detectable pulse width of about 10ns, and dynamic range of energy density of 0.02–100µJ/cm2.

Measurement of Three Parameters of a Photorefractive Crystal Ce:KNSBN in Codirectional Two-Wave Mixing

We present a method of measuring the parameters of a photorefractive crystal in codirectional two-wave mixing that is suitable for two-wave mixing in the intermediate stage (before saturation). Three parameters of a crystal, the exponential gain coefficient, saturation intensity and intensity absorption coefficient, can be measured simultaneously by using this method. The three parameters of a Ce:KNSBN are measured and the measured data are checked by another independent measurement.