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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%.

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.

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.

A self-starting mode-locked femtosecond laser is accomplished with an oxoborate self-frequency doubling crystal Yb:YCa4O(BO3)3 (Yb:YCOB) as the gain medium and a semiconductor mirror as the saturable absorber. Pumped by a 976-nm fiber-coupled diode laser with 50-μm core diameter, stable mode-locked laser pulses up to 430 mW were obtained at a repetition rate of 83.61 MHz under 5-W pump power. The autocorrelation measurement shows that the pulse duration is as short as 150 fs by assuming the sech2 pulse shape at a central wavelength of 1048 nm. This work has demonstrated a compact and reliable femtosecond laser source for prospective low-cost applications.

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.

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 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.

A new LD end pumped Nd：LuVO4 microchip laser was reported for the first time. Study of laser properties was carried out on the effects of different Nd3+ doped concentration，different cavity length and different 1064nm transmission. The relationship between the maximum output power and LD performance temperature was measured at different pump power. 923mW of continuous output at 1064nm with TEM00 mode was obtained at 2W pump power，the pump threshold being 48mW. The slope efficiency was 52%，and increased to 59% when the microchip was cooled.