Zhang Dong-Xiang

Diode-Pumped Self-Q-Switched Cr,Nd:YAG Laser with High Average Output Power

A diode end-pumped self-Q-switched Cr,Nd:YAG laser was established with pulse duration in the range of 8–10 ns. The maximum average output power was 4.4 W and the slope efficiency was 27% using an output coupler of R = 70%. At pumping power of 17.4 W the laser produces high-quality pulses at 1064 nm in a TEM00-mode.

Rectifying Characteristics and Transport Behavior in a Schottky Junction of CaCu3Ti4O12 and Pt

CaCu3Ti4O12 (CCTO) thin films were fabricated on ITO-covered MgO (100) substrates. The rectification characteristics were observed in the CCTO capacitance structure with Pt top electrodes at temperatures ranging from 150 K to 330 K, which are attributed to the formation of a Schottky junction between n-type semiconducting CCTO and Pt due to the difference of their work functions. At low forward-bias voltage, the current-voltage characteristics of the Schottky junction follow . A strong decrease in ideality factor with the increasing temperature is obtained by linear fitting at the low bias voltage.

Green Output of 1.5 W from a Diode-Pumped Intracavity Frequency-Doubled Self-Q-Switched and Mode-Locked Cr,Nd:YAG Laser

The spontaneous emmission (SE) progress of polarized atoms in a stratified structure of air-dielectric (D0-metal(M)-dielectric(D1)-air can be controlled effectively by changing the thickness of the D1 layer and rotating the polarized direction of atoms. It is found that the normalized SE rate of atoms located inside the D0 layer crucially depends on the atomic position and the thickness of the D1 layer. When the atom is located near the D0-M interface, the normalized atomic SE rate as a function of the atomic position is abruptly onset for the thin D1 layer. However, with the increasing thickness of the D1 layer, the corresponding curve profile exhibits plateau and stays nearly unchanged. The substantial change of the SE rate stems from the excitation of the surface plasmon polaritons in metal-dielectric, and the feature crucially depends on the thickness of D1 layer. If atoms are positioned near the D0-air interface, the substatial variation of the normalized SE rate appears when rotating the polarized direction of atoms. These findings manifest that the atomic SE processes can be flexibly controlled by altering the thickness of the dielectric layer D1 or rotating the orientation of the polarization of atoms.

Diode-pumped passive Q-switched 946 nm Nd : YAG laser with a GaAs saturable absorber

We report, for the first time to our knowledge, a diode-pumped passive Q-switched 946 nm Nd:YAG laser by using a GaAs as saturable absorber. The maximum average output power is 1.24 W at an incident pump power of 15 W, corresponding to a slope efficiency of 10%. Laser pulses with pulse duration of 70 ns and repetition rate of 330 kHz are generated.

Observation of Antiphase State in a Self-Q-switched Nd, Cr:YAG Laser

We experimentally investigate the antiphase dynamics phenomenon in a self-Q-switched Nd, Cr:YAG laser operating at 946 nm. Due to the effect of spatial hole burning, the Q-switched pulses sequences of one, two and three modes at different pump power are observed. The experimental results show that the pulse sequences display classic antiphase dynamics.

Spectroscopic investigation of a new crystal: Nd3+,Yb3+:YVO4

The absorption and emission spectra of the YVO4 single crystal co-doped with 1 at.% Nd3+ and 1 at.% Yb3+ are investigated. The efficient Nd3+ → Yb3+ energy transfer and the back transfer (Yb3+ → Nd3+) are observed at room temperature. The fluorescence lifetime of the 4F3/2 level of Nd3+ in Nd, Yb:YVO4 is measured under 808 nm laser light excitation. The efficiency of Nd3+ → Yb3+ energy transfer in YVO4 is determined to be about 34%.

Antiphase State in Passively Q-Switched Yb:YAG Microchip Lasers with a Nd,Cr:YAG as Saturable Absorber

We experimentally investigate the antiphase dynamics phenomenon that occurs in a diode-pumped passively Q-switched Yb:YAG multimode laser with a Nd,Cr:YAG saturable absorber. Due to the effect of spatial hole burning, the multimode lasers with one, two, or three modes at different pump power are observed, and the pulses sequences display classic antiphase dynamics.

Three-wavelength generation from cascaded wavelength conversion in monolithic periodically poled lithium niobate

Tunable coherent emission is generated in a single-pass, cascaded wavelength conversion process from mode-locked laser-pumped monolithic periodically poled lithium niobate (PPLN). Three ranges of wavelength, including visible output from 628 nm to 639 nm, near-infrared output from 797 nm to 816 nm, and mid-infrared output from 3167 nm to 3459 nm, were obtained from the monolithic PPLN, which consists of a 10-mm section for 532-nm-pumped optical parametric generation (OPG) and a 7-mm section for 1064-nm-pumped sum frequency generation (SFG). A pump-to-signal conversion efficiency of 23.4% for OPG at 50 °C and a quantum efficiency of 26.2% for SFG at 200 °C were obtained.

Self-Q-Switched and Mode-Locked Cr,Nd:YAG Laser under Direct 885 nm Diode Laser Pumping

A simultaneous self-Q-switched and mode-locked laser in a direct 885 nm diode-pumped Cr,Nd:YAG crystal is demonstrated. An improvement of the slope efficiency (38.1%) in the absorbed pump power is obtained under direct pumping. Under the maximum output power of 3.36 W, the repetition rate of the Q-switched envelopes is 95 kHz and the corresponding pulse width is 400 ns. Almost 100% mode-locked modulation depth is observed at the output power of 75 mW. The repetition rate of mode-locked pulses within a Q-switched envelope is 130 MHz, and the mode-locked pulse width stays within the scale of 500 ps.

Diode-Pumped Passively Q-Switched Yb:YAG Microchip Laser with a GaAs as Saturable Absorber

A passively Q-switched Yb: YAG microchip laser has been constructed by using a doped GaAs as the saturable absorber as well as the output coupler. At 13.5 W of pump power the device produces high-quality 3.4 muJ 52 ns pulses at 1030nm with a pulse repetition rate of 7.8kHz in a TEM00-mode.