Hai-feng Wang

LiTaO3 crystal periodically poled by applying an external pulsed field

A method of periodically poling LiTaO3 single crystal at room temperature by applying an external pulsed field is proposed. The relationship between the growth of inverted domains and switching current as well as switching time has been studied. The growth of inverted domains can be controlled by the duration of the pulsed field. The domain structure with period Λ≳8 μm has been fabricated in a 0.3‐mm‐thick plate of LiTaO3 by partial switching.

Second‐harmonic generation of blue light in bulk periodically poled LiTaO3

We fabricated a periodic domain structure in a 0.5 mm thick slab of LiTaO3 crystal by applying an external pulsed field at room temperature. Using a pulse dye laser with a pulsewidth of 8 ns and a repetition rate of 10 Hz, third‐order quasi‐phase‐matched second‐harmonic blue‐light generation is demonstrated by free propagation of a 862.6 nm fundamental Gaussian beam in a 4 mm long LiTaO3 slab, with a single pulse energy of 0.072 mJ and an energy conversion efficiency of 5.7%.

Study on the formation mechanism of a complex domain structure in LiNbO3

A complex domain structure in LiNbO3 is fabricated by proton exchange followed by heat treatment. Domain inversion at the +c and −c faces as well as reinversion in the inverted region near the +c surface are observed experimentally. The proton and lithium concentrations are measured by secondary ion mass spectroscopy. It is found that the proton profile peaks away from the surface due to indiffusion and outdiffusion. The domain inversion mechanism is discussed. An internal electric field model is proposed which is based on the concentration gradient of proton and lithium deficiency.

Second-order quasi-phase-matched blue light generation in a bulk periodically poled LiTaO3

Domain reversal in LiTaO3 with period 6.5 mu m and 1:3 duty cycle has been obtained by using a partially switching technique in a 0.25 mm thick sample. A CW second-order quasi-phase-matched second-harmonic-generation experiment yielded a 12 mu W, 407 nm blue light output for 200 mW, 814 nm fundamental input. The technique can be used for the fabrication of the periodic poled LiTaO3 for bulk violet and ultraviolet second-harmonic generation and for the fabrication of other ferroelectric microstructure materials.

Field-induced periodic poled bulk using Al electrodes

Field-induced periodic domain reversal has been achieved in a 0.5 mm thick, c-cut sample with Al electrodes by optimizing fabrication conditions. The quality of the sample has been tested by measuring the efficiency of second harmonic blue light generation and its tuning behaviour.

Study on the proton profile in proton-exchanged and heat-treated LiNbO3 with domain reversal

The domain inversion in LiNbO3 is fabricated by proton exchange and rapid heat treatment. The proton concentration is measured by secondary-ion mass spectroscopy. A modified diffusion model is proposed, the result of which agrees well with the measured data. Comparisons with the existing models are made, which suggests that our model may be more extensively applicable.

First-principles study of lattice thermal conductivity in ZrTe5 and HfTe5

Recently, the layered transition-metal pentatellurides ZrTe5 and HfTe5 have attracted increasing attention because of their interesting topological electronic properties. Nevertheless, some of their other good physical properties seem to be ignored now. Actually, both ZrTe5 and HfTe5 have high electric conductivities (>105 Ω−1 m−1) and Seebeck coefficients (> 100 μV/K) at room temperature, thus making them promising thermoelectric materials. However, the disadvantage is that the thermal conductivities of the two materials are relatively high according to the few available experiments; meanwhile, the detailed mechanism of the intrinsic thermal conductivity has not been studied yet. Based on the density functional theory and the Boltzmann transport theory, we present here the theoretical study of the intrinsic lattice thermal conductivities of ZrTe5 and HfTe5, which are found to be in the range of 5–8 W/m⋅K at room temperature and well consistent with the experimental results. We also find that the thermal ...

Study on domain inversion in LiNbO3 by Ti-indiffusion

Abstract In this paper, the fabrication of periodic domain inversion on the +C face of LiNbOs by Ti-indiflusion method has been presented. The influence of different gases and varying heat treatment times on domain inversion has been investigated. The mechanism of domain inversion has been discussed.

Ferroelectric domain inversion in LiTaO3 single crystal by applying electric field

Abstract Ferroelectric domain inversion in LiTaO3 single crystal has been achieved at room temperature by applied external electric field. The polarization inversion in the material exhibited different dynamic characteristics under high field(E > 20kV/mm) and low field(E < 20kV/mm), respectively. The inversion behaviors under high field have been studied

Time-dependent ferroelectric coercive field after domain inversion in LiNbO3

It was found that the ferroelectric coercive field of LiNbO3, both in forward and reverse direction, vary with time after domain inversion. The existence of an internal field decaying as e-t/(tau ) is proposed, and the related coefficients are fitted.