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In order to study the output characteristic of Nd∶GdVO4 influenced by 808 nm and 879 nm,coupled by comparison of the CW output laser efficency pumped by the two different wavelengths,the structure of the energy levels of the Nd∶GdVO4 crystal is investigated,and it is found that another absorption wavelength of 879nm is realatively strong.The output characteristics under 808 nm LD pumping and under 879 nm LD pumped are analyzed by experiments.The processes of pumping Nd∶GdVO4 crystal by laser beams of 808 nm and 879 nm wavelength are different.The pumping by 808 nm LD is a process of transfering energy by an indirect way.During the process,the obvious hot load will occur.But pumping by 879 nm LD will drive Nd3+ ions into the laser emitting level,to avoid useless heat generation during no-radiation transition and reduce the thermal effects efficiently.Theoretically,the quantum efficiency of 879 nm is greater than that of 808 nm,so the heat produced from the crystal with pumping should be small.The way of pumping Nd∶GdVO4 crystal is used by laser diode from straight line cavity experimental program,and the process of producing 1 063 nm CW by pumping Nd∶GdVO4 crystal is studied using two different pumping wavelengthes.Lasers under these two different pumping wavelengths are obtained.With the same experimental conditions,the output slope efficiency of pumping crystal by 879 nm LD is a bit higher than by 808 nm in low power.But the output slope efficiency of 879nm is greater than that of 808 nm in high power,and the maximum reaches 38%.Meanwhile,a laser of 1 341 nm is achieved when the pumping at 808 nm,which could be a kind of light source for optical communication.

Stimulated Raman scattering (SRS) of picosecond pulses is investigated in a new crystal SrWO4. The second harmonic generation of a mode-locked Nd:YAG laser system is used as the pump source. In an external single-pass configuration, the SRS thresholds for the first to the fourth Stokes lines are measured. For the first Stokes line, the steady-state gain coefficient of the SrWO4 crystal is calculated to be 15.96 cm/GW. In our experiment, as many as five Stokes lines (559.23 nm, 589.61 nm, 623.49 nm, 661.50 nm, 704.44 nm) and three anti-Stokes lines (506.97 nm, 484.34 nm, 463.65 nm) are observed, and the total conversion efficiency is as high as 62%.

The polycrystalline materials of SrWO4 were synthesized by means of a solid phase reaction with analytical purity SrCO3 and WO3 at high temperature. The transparent SrWO4 single crystal with dimension of ϕ 22 mm×40 mm has been successfully grown along a-axis by Czochralski method. X-ray powder diffraction results show that the as-grown SrWO4 single crystal belongs to tetragonal system and I41/a space group. The measured density of SrWO4 is 6.439 g·cm−3 by buoyancy method. The effective segregation coefficients of W and Sr elements in SrWO4 single crystal are close to 1 by the X-ray fluorescence method.

We report an efficient pumping scheme which involves a direct excitation of the upper lasing level of a four-level laser in a Nd-doped Ca3(NbGa)2-xGa3O12 (Nd:CNGG) by using a tunable Tr.sapphire, 700–920 nm, cw pump source. The slope efficiency is improved from 10.5% of the traditional band pumping at 808nm to 21.8% of the direct pumping at 882 nm. The influence of pumping wavelength on lasing is discussed. We present a scheme of double pumping for lasing.

Using an external couple cavity and a pump beam compression system, efficient 1.5 μm eye-safe Raman laser is obtained based on BaWO4 crystal. The largest output energy is 8.5mJ, corresponding to an electric-optical conversion efficiency of 47%.

A simplified n- ZnO/ p- Si heterojunction has been prepared by growing n- type ZnO rods on p- type silicon wafer through the chemical vapour deposition method. The reflectance spectrum of the sample shows an independent absorption peak at 384 nm, which may be originated from the bound states at the junction. In the photoluminescence spectrum a new emission band is shown at 393 nm, besides the bandedge emission at 380 nm. The electroluminescence spectrum of the n- ZnO/ p- Si heterojunction shows a stable yellow luminescence band centred at 560 nm, which can be attributed to the emission from trapped states. Another kind of discrete ZnO rod has also been prepared on such silicon wafer and is encapsulated with carbonated polystyrene for electroluminescence detection. This composite structure shows a weak ultraviolet electroluminescence band at 395 nm and a yellow electroluminescence band. These data prove that surface modification which blocks the transverse movement of carriers between neighbouring nanorods plays important roles in the ultraviolet emission of ZnO nanorods. These findings are vital for future display device design.

A compact laser diode-pumped solid-state Nd:LuVO4 acousto-optic Q-switched laser is demonstrated at 916 nm of a quasi-three level for the first time. A pulse width of 130 ns is observed when the pulse-repetition frequency is 10 kHz. The laser experiment shows that the Nd:LuVO4 crystal can be used for efficient diode-pumped Q-switched lasers.

We report the compact diode-pumped continuous-wave (CW) Nd:LuVO4 lasers operated at 916 nm and 458 nm for the first time. The maximum output power of 780 mW at 916 nm laser is obtained with a slope efficiency of 9.3%. We generate 50 mW of 458 nm blue laser employing a type-I critical phase-matched LBO crystal.

The barrier planar waveguides are fabricated for the first time in z-cut LGS (La3Ga5SiO14) crystals by 3.0 MeV and 6.0 MeV carbon ion implantations with dose of 2×1015ions/cm2 at room temperature. Four and six dark modes were observed by the prism-coupling method, respectively. The refractive index profiles were reconstructed by using the reflectivity calculation method. There are about 1.6% and 0.9% decreases at the optical barriers in the 3.0 MeV and 6.0 MeV cases, and the positions of the optical barriers are close to that of the damage peaks calculated by the TRIM'98 (Transport of Ions in Matter) code. It is found that the refractive index change may partly be due to the damage induced by the nuclear collision.

Ce,Pr:YLuAG pure phase powder was synthesized by co-precipitation method and calcined at 1450°C, which had a garnet structure. The feed rod was prepared by press forming and solid state sintering. TEM showed that the sintered rod had good crystallinity and density. Ce,Pr:YLuAG single crystal was grown by the floating zone method. The as-grown crystal was transparent with a pale yellow color, and small cracks were observed in the shoulder. The transmittance of the crystal is 81.8%, which is close to the theoretical value 84.2%. Under 460 nm excitation, Ce,Pr:YLuAG crystal shows the emission band of Ce at 530 nm and peak of Pr at 610 nm, which shows that Ce can transfer the energy to Pr. However, only Pr emission peak appears when it is excitated at 487 nm. The color coordinate is located at (0.474, 0.495) which shifts to red zone compared with commercial Ce:YAG yellow phosphor. As a result, Ce,Pr:YLuAG crystal is more suitable to fabricate white LED.

We demonstrate a passively cw mode-locked Nd:LuVO4 laser operating on the quasi-three-level at 916 nm with a Z-folded resonator. Using a semiconductor saturable absorber mirror (SESAM) as the passive mode-locking device, we achieve stable cw mode locking with 6.7 ps pulse duration at repetition rate of 133MHz and 88mW average output power under the pump power of 17.1 W.

We report a diode stack end-pumped Nd:GdVO4 slab laser with a near-diffraction-limited beam. The output power of 45.8 W at 1064 nm is obtained under the pumping power of 147 W, with the optical-optical conversion efficiency of 31.2%, and the slope efficiency is 39.6%.

Continuous-wave laser operation is demonstrated at room temperature with a new disordered Yb:CLNGG crystal. A maximum output power of 5.05 W is generated with 7.8 W of pump power absorbed in the crystal, resulting in an optical-to-optical efficiency of 65%, whereas the slope efficiency is determined to be 92%, approaching the limit imposed by the quantum defect in the laser emission process.

The room-temperature polarized absorption and emission spectra of Yb doped mixed vanadates Yb 0.005 :Y 0.298 Gd 0.697 VO 4 , Yb 0.007 :Y 0.407 Gd 0.586 VO 4 , and Yb 0.009 :Y 0.575 Gd 0.416 VO 4 have been studied. The results show that the strongest absorption and emission, occurring at wavelength of 985 nm, correspond to the π polarization, depending on the composition the maximum absorption cross section ranges from 4.8 to 8.5×10 -20 cm 2 , with bandwidths of 9.5—9.9 nm, whereas the maximum stimulated emission cross section varies in the range of 5.8—10.3×10 -20 cm 2 . Continuous-wave laser operation has been realized at room temperature with the mixed crystals through longitudinal pumping with a diode laser. It was found that the laser oscillation behavior differs significantly from one mixed crystal to another:in the case of T =2% ( T is the output coupling of the resonator), the coexistence and switching of σ, π polarization states occur on reducing the pump power in the laser oscillation of Yb 0.005 :Y 0.298 Gd 0.697 VO 4 and Yb 0.009 :Y 0.575 Gd 0.416 VO 4 , while the laser oscillation of Yb 0.007 :Y 0.407 Gd 0.586 VO 4 is capable of maintaining its π polarization state. In the case of T =5%, however, the laser oscillation generated with Yb 0.009 :Y 0.575 Gd 0.416 VO 4 is purely σ-polarized, whereas the laser behavior of Yb 0.005 :Y 0.298 Gd 0.697 VO 4 is similar to that exhibited in the case of T =2%.

We have studied the effect of optical bistability exhibited in the laser oscillation of Yb:LuVO4, Yb:YVO4, and Yb:GdVO4, the three Yb doped vanadate crystals. The bistability range can be in excess of 1 W in terms of the pump power absorbed by the crystal. At the high-power-end side of the bistability region, i.e., the upper threshold for laser oscillation, discontinuous growing in the output power takes place, along with large fluctuations in the laser intensity occurring on sub-millisecond time scale. It is found that the bistability effect is affected significantly by the output coupling of the resonator, the crystal thickness, and the thermal effect existing in the crystal.

We conducted an investigation into the polarized absorption and emission spectra, the absorption for unpolarized pump light, and the continuous-wave (cw) laser properties of the Yb:KLu(WO4)2 crystal. The low symmetry of the crystal leads to strong anisotropy in the crystal spectroscopy; the strongest absorption and emission occur in the polarization direction parallel to the Nm principal axis. The Ng-cut crystal has highest absorption efficiency for unpolarized pump light and largest potential for generating laser output power. With 11 W of cw output power produced by using a 2 mm thick crystal, the optical-to-optical conversion and slope efficiencies amount to 68% and 80%, respectively, with respect to the absorbed pump power.

With an ultra-cavity single-pass configuration, the stimulated Raman scattering (SRS) of a new crystal YbVO4 was investigated. When the pump source was a 532 nm pico-seconds laser, as many as three Stokes lines (558.47, 587.92 and 620.67 nm) and one anti-Stokes line (507.58 nm) were observed. The steady-state Raman gain coefficient for the first Stokes line was measured to be 17.8±0.2 cm/GW, and the total conversion efficiency reached 37%. For the first time, the SRS of YbVO4 crystal for 355 nm pump laser was realized. The first Stokes line (366.11 nm) was observed, and according to the pumping thresholds, the steady-state Raman gain coefficient was determined to be 29.0±0.3 cm/GW.