T.B. Wang

Self-modulation of light in piezoelectric crystals.

Spectroscopic measurements were used to monitor the optical interference of ordinary (o-ray) waves with extraordinary (e-ray) waves by incidence of plane-polarized light and transmission through piezoelectriccrystals (alpha-quartz, LiNbO3, and LiTaO3). This observation confirms that the rotations of the vibration planes of the o- and e-ray waves originate from the dynamic gratings induced by the electric field of the incident light. This is a self-modulation process of the polarized incident light in piezoelectric crystals.

THE FORMULAS FOR THE SECONDARY ELECTRON YIELD AT HIGH INCIDENT ELECTRON ENERGY FROM GOLD AND ALUMINUM

Based on the main physical processes of secondary electron emission from metals, the relation that the product of the number of secondary electron released per primary electron at high incident electron energy and the (n-1)th power of incident energy of primary electron is equal to constant C was deduced, where n is the energy exponent, based on the relation between the number of secondary electron released per primary electron at high incident electron energy and secondary electron yield. The relation that the product of the secondary electron yield at high incident electron energy and the (n-1)th power of incident energy of primary electron is equal to constant D was deduced. The constant D and the energy exponent n of the primary electron in the energy range 10 to 100 keV hitting on gold and aluminum are computed with the ESTAR program and experimental results in scanning electron microscope (SEM), respectively, therefore, the formulas for the incident energy dependence of secondary electron yield in the energy range 10 to 100 keV from gold and aluminum were deduced. The formulas were proved to be true by experimental results in SEM. The results were discussed and a conclusion was drawn. The formulas from gold and aluminum were successfully deduced.

Polarization state of the transmitted light in the absorptive infrared range through α-quartz

Two peaks of the transmitted waves at 580 and 665 cm � 1 were found to be perpendicularly polarized after propagating through a-quartz, which correspond to the ordinary and extraordinary waves, respectively. This is a new dichroic property of a-quartz in the infrared frequency region, namely the polarization state of the incident light is changed after propagation through a-quartz. # 2003 Elsevier Ltd. All rights reserved.

Relationship between the frequency of the main LO mode of silica glass and angle of incidence

The infrared reflection spectra of silica glass were monitored at different angles of incidence and different polarization directions of the incident light. The frequency of the transverse optic mode in the vicinity of 1129 cm−1 remains a constant under different conditions, whereas the frequency of the longitudinal optic mode near 1260 cm−1 and the ratio RLO/RTO are functions of the angle of incidence and polarization direction of the plane polarized incident light, where R denotes the reflectance. These observations are due to the gradient in the vibration amplitude in the direction perpendicular to the glass surface.

Universal Formula for Secondary Electron Yield of Metals at High Electron Energy and Incident Angle θ

On the basis of the main physical processes of secondary electron emission, the relationships among the incident energy (Wp0) of primary electrons, the number of secondary electrons (δPEθ) released per primary electron entering the metal at high electron energy and incident angle θ and incident angle (θ) are deduced. In addition, the relationship between the number of secondary electrons (δPE0) released per primary electron entering the metal at θ= 0° and Wp0 is determined. From the experimental results, the relationships among the ratio βθ (the subscript θ means the primary electron is incident at θ in this paper), the ratio at θ= 0° (β0) and θ are obtained. On the basis of relationships among δPEθ, δPE0, βθ, β0, backscattered coefficient ηθ, backscattered coefficient at θ= 0° (η0), secondary electron yield δθ, and secondary electron yield at θ= 0° (δ0), the universal formula for expressing δθ using δ0, ηθ, η0, and θ is deduced. The secondary electron yield calculated from this universal formula and the yields measured experimentally from aluminum and copper are compared. The results suggest that the proposed formula is universal for the estimation of secondary electron yields in the angle range of 0–80° and the energy range of 10–102 keV.

A high efficient end-pumped TEM00 laser with pulse repetition rate of 5 kHz

An end-pumped Nd:YVO4 laser fiber-coupled diode was designed. A maximum output power of 4.74 W TEM00 mode CW laser was obtained for a pump power of 10.5 W. The optical efficiency and slope efficiency were measured as 45.1 and 57.8% at 1064 nm, respectively. In Q-switching operation, 4.45 W average power at a pulse repletion rate of 5 kHz was produced, with a stability of pulse peak value <2%.

Competition Between Singlet and Triplet Superconductivity

The competition between singlet and triplet superconductivity is examined in consideration of correlations on an extended Hubbard model. It is shown that the triplet superconductivity may not be included in the common Hubbard model since the strong correlation favors the singlet superconductivity, and thus the triplet superconductivity should be induced by the electron–phonon interaction and the ferromagnetic exchange interaction. We also present a superconducting qualification with which magnetism is unbeneficial to superconductivity.

A possible explanation of the phase diagram of cuprate superconductors

Abstract A d–p pairing curve that is consistent with the pseudogap curve observed in experiments is found on a d–p model on phonon mechanism. On the discovery we suggest that there are two pseudogaps associated with the nearly localized d–p pairs and nearly free p–p pairs. The p–p pairs look like bosons and are responsible for superconductivities.