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CsSrI3:3%Eu (Φ10×55mm), CsSrI3:5%Eu (Φ10×50mm) and CsSrI3:7%Eu (Φ10×45mm) single crystals have been successfully grown by the edge-defined film-fed growth method for the first time, with the growth rate reaching 10-20mm/h. We designed a crystal growth device that achieved the first growth of this binary scintillation crystal by the EFG method. The raw material purification, temperature gradient of experimental device and growth rate, which are the effect factors of crystal quality, were systematically investigated. Moreover, the effect of Eu2+ concentration on optical properties were studied. The Eu2+ 5d-4f emission band was observed at 450-455nm, and the PL decay time was determined as 1.32µs for CsSrI3:3%Eu, 1.35µs for CsSrI3:5%Eu and 0.73µs for CsSrI3:7%Eu.

The effect of the doping concentration on the anisotropic thermal properties of Yb:YCOB crystals was systematically evaluated for the first time to our knowledge. The thermal expansion, thermal diffusion, specific heat and thermal conductivity of Yb:YCOB crystals with different doping concentrations were measured. The thermal expansion and conductivity along the principal axes were calculated, and the rotation angles between the thermal frame and the reference coordinate were determined. The relationship between the doping concentration and the anisotropic thermal properties was discussed with the results that the doping concentration was an anomaly found to have a slight impact on anisotropic thermal properties. It was concluded that the YCOB crystal can be doped with a high concentration of Yb3+ ions to improve the conversion efficiency in the laser process without deteriorative thermal problems.

By balancing energy transfer and thermal effects, we demonstrate efficient erbium-doped yttrium gallium garnet (Er:YGG) crystal lasers at a wavelength of 2.82-2.92 μm for the first time, to the best of our knowledge. Associated with the influence of doping concentration on energy transfer and thermal effects, the Er3+ doping concentration was optimized to be 10 at.%, and with the optimized crystal, the maximum continuous-wave output power was 1.38 W, corresponding to the slope efficiency of 35.4% approaching the theoretical quantum limits. The thermal effects during the laser process were discussed. We believe that this work should be helpful for optimizing the erbium-doped gain for the 3 μm laser and the development of 3 μm lasers.

We directly measured the phase-matching angles of second-harmonic generation and difference-frequency generation up to 6.5 µm in the Langanate crystal La3Ga5.5Nb0.5O14 (LGN). We also determined the nonlinear coefficient and damage threshold. We refined the Sellmeier equations of the ordinary and extraordinary principal refractive indices, and calculated the conditions of supercontinuum generation.

We demonstrated the output power enhancement of a self-frequency-doubled laser with Nd3+-doped lanthanum calcium borate La2CaB10O19 (Nd:LCB) crystals by selective excitation of its inequivalent active centers. When the Nd3+ ions located in the Ca2+ sites were excited in the Nd:LCB crystal, the fundamental laser at the wavelength of 1066 nm was successfully realized, which can keep the self-frequency-doubled wavelength away from the self-absorption peak of Nd3+ ions at about 523 nm. By optimizing the key parameters, the maximum output power of 801 mW was achieved with the frequency-doubling at the wavelength of 533 nm, and the enhancement of output power was about 7.8 times compared with the results by excitation of Nd3+ ions in the La3+ sites. Up to now, this output power of the self-frequency-doubled laser represents the highest one in the Nd:LCB crystal, and the efficient emission at 533 nm should have promising applications in the visible range, such as laser displays, optical data storage, laser printing, etc. Meanwhile, the selective excitation of inequivalent active ions and the enhancement of the self-frequency-doubled laser may provide some inspiration for the investigation of multi-functional materials.

Stimulated Raman scattering (SRS) is an important technique for broadening the laser spectra. The Raman crystals with large dimensions and high thermal conductivity are favorable by SRS. Zinc tungstate (ZnWO4) belonging to a monoclinic system has been grown by the Czochralski method with the dimensions of Φ 35 mm × 70 mm. The thermal properties were evaluated and analyzed in several aspects, including the density, specific heat, thermal expansion coefficient, and thermal conductivity. Thermal conductivity was calculated to be 5.412 Wm−1K−1 along the c-axis, which is about two times larger than the famous BaWO4 and SrWO4. Meanwhile, the optical properties including transmission and Raman spectra and Raman shift were measured and the stimulated Raman scattering performance of ZnWO4 crystal was demonstrated. The results show that the thermal conductivity decreases with increasing temperature. Furthermore, the thermal focal lengths were theoretically estimated. Along the a direction, the light with a wavelength of 532 nm can be shifted to the light at 558.95 nm, which is in good accordance with the spontaneous Raman spectrum. All the analyses and results above show that ZnWO4 is a promising solid-state Raman laser crystal.

We experimentally demonstrate a ZnGePsub2/subbased optical parametric oscillator (ZGP-OPO) with a record of the optical-to-optical conversion efficiency. To improve the conversion efficiency, we design and construct a double-pass pumped high-gain OPO and a matched large-sized high-peak-power pump beam to suppress the spatial walk-off and conversion. Pulse energy of 19 mJ with pulse width of 27.8 ns at 5 Hz in the mid-infrared 3-5 μm waveband is obtained in the doubly resonated ZGP-OPO, the beam quality Msup2/supis about 9.6, and the corresponding optical-to-optical conversion efficiency reaches up to 75.7%.

High-quality KDP and DKDP crystals with 12%, 70% and 80%-deuterium content were grown by the conventional temperature cooling method. The nonlinear optical characteristics of K(DxH1-x)2PO4 crystals, including nonlinear absorption and refraction, were systematically investigated through the Z-scan method at λ = 532 nm. The results demonstrate the existence of nonlinear absorption and refraction, and a nonlinear refractive index with a positive sign indicates the generation of self-focusing effect. Moreover, the results indicate that nonlinear absorption and refraction were associated with crystal direction and structure, especially the distribution of H2PO4 - or D2PO4 - groups. For K(DxH1-x)2PO4 crystals, a similar rule of β was z > I > II, while n2 (or χR(3)) was z > II ≈I. These results will evoke more attention to KDP and DKDP applications, especially frequency conversion and electro-optic switch.

Recent progress in strong-field physics has stimulated the quest for intense mid-infrared ultrashort light sources. Optical parametric amplification (OPA) is one promising method to build up such sources, however, its development significantly relies on the availability of suitable nonlinear crystals. Here, we introduce a positive uniaxial crystal La3Ga5.5Nb0.5O14 (LGN), which exhibits a favorable set of optical properties for the application in a mid-IR OPA. We theoretically evaluate the performance of LGN as the nonlinear crystal of a mid-infrared OPA, with an emphasis on the bandwidth characteristic. We find that this crystal can support broadband amplifications across its entire mid-infrared transparent region up to 6 μm, outperforming other commonly-used mid-infrared crystals in terms of gain bandwidth. Few-cycle mid-infrared pulses at various wavelengths can be generated from the LGN-based optical parametric chirped-pulse amplifiers.

A light beam with a helical phase is associated with an optical vortex and carries optical orbital angular momentum. Mode-locked optical vortex pulses impart orbital angular momentum to photons in short pulses and have attractive applications. However, due to the conflict between mature mode-locking and the generation of optical vortices, directly generated mode-locked optical vortex short pulses seem to be unavailable, thus constraining the development and applications of optical vortex short pulses. Laguerre-Gaussian (LG) modes are eigenfunctions for a laser cavity. Besides carrying optical orbital angular momentum, LG beams also have self-healing and quasi-nondiffracting properties. Here, we report the realization of a self-mode-locked LG lasers with tunable orbital angular momentum. By coupling between the thermal and optical fields, the orbital angular momentum was found to be staged. These results verify the possibility of direct mode-locking of optical vortices, and may open the way for several applications of short pulses. Moreover, mode-locked pulses with high-repetition rates also have particularly attractive applications such as optical frequency comb spectroscopy, high capacity optical networks, spectroscopy of metallic nanoparticles, arbitrary waveform generation, etc..

Growth of optical-quality crystals with a borate anionic group and small-diameter cations is challenging. By compensating for the volatilization of boracic acid, an optical-quality Yb3+:ScBO3 laser crystal suitable for laser applications has been grown by the Czochralski method. The thermal and spectral properties of Yb3+:ScBO3 were experimentally and theoretically studied, including the thermal expansion, thermal diffusivity, specific heat, thermal conductivity, and the absorption and low-temperature emission spectra. The results indicate that this crystal exhibits a thermal conductivity that increases with temperature, and large energy storage properties that indicate promise for utilization in moderate power lasers. A continuous-wave Yb3+:ScBO3 crystal laser has, to the best of our knowledge, been demonstrated for the first time, with a maximum output power of 106 mW. All the results are indicative of a novel promising laser medium for applications in low and even moderate power lasers.

We experimentally prove the broad emission band of Nd:LGS disordered crystal and demonstrate a diode-pumped passively mode-locked femtosecond Nd-doped La3Ga5SiO14 (Nd:LGS) laser for the first time. With a birefringent filter inserted into the cavity, the tunable continuous wave (CW) laser of over 60 nm from 1045.2 nm to 1105.3 nm is achieved, which is the widest tuning range with Nd-doped crystals to our knowledge. Further in mode-locked operation, femtosecond pulses with pulse duration of 381 fs, average output power of 75 mW and repetition rate of 134.4 MHz are obtained at the central wavelength of 1066 nm. It is suitable to be a compact seed for femtosecond laser amplifiers.

We realized a stable Kerr-lens mode-locked operation in a Yb:YCa4O(BO3)3 laser. Pulses as short as 73 fs were generated at the central wavelength of 1043 nm, with a bandwidth of 19 nm. The femtosecond oscillator operating at a repetition rate of 110 MHz delivers an average output power of 70 mW under 3 W diode pump power. To the best of our knowledge, this is the first demonstration of a pure Kerr-lens mode-locked operation in a diode-pumped Yb:YCa4O(BO3)3 laser.

Absorption and emission spectra of Er3+:LuVO4 for the 4I15/2 ↔ 4I13/2 transitions have been investigated at room and cryogenic temperatures. A corrected energy level diagram was built. An efficient, resonantly pumped Er3+:LuVO4 laser operating at 1609 nm (π-polarization) or 1597.5 nm (σ-polarization) was demonstrated. For CW pumping into the 1532 nm absorption line by a narrow-bandwidth Er-fiber laser, the maximum output power was ~4.6 W and the maximum slope efficiency was 64% - the best reported efficiency of Er-doped vanadate lasers at room temperature. Resonant pumping into the 1529 nm absorption band with a fiber-coupled diode laser yielded a 62% slope efficiency. To the best of our knowledge, this is the first report on an Er:LuVO4 laser.

We report a laser-diode pumped continuous-wave (cw) and passively Q-switched eye-safe laser at about 1.42 μm with the neodymium-doped yttrium gallium garnet (Nd:YGG) crystal for the first time to our knowledge. The composite Nd:YGG crystal was developed originally. A systematic comparison of laser performance between the homogeneously doped and composite Nd:YGG crystal was made, which showed that the composite Nd:YGG manifested less thermally induced effects. Cw output power of 2.06 W was obtained with the slope efficiency of 20.7%. With a V:YAG as a saturable absorber, the passive Q-switching at 1.42 μm was gotten with the pulse width, pulse energy, and peak power of 34 ns, 46.7 μJ, and 1.4 kW, respectively. The present work should provide a potential candidate for the generation of eye-safe lasers.

The spectra of Er:Lu2O3 have been studied between 7 K and room temperature, particularly for transitions between the 4I13/2 and 4I15/2 manifolds. This includes the determination of energy levels for Er in the C2 site and some levels for the C3i site, as well as absorption and stimulated emission cross sections and radiative lifetimes. At cryogenic temperatures, the emission lines at 1576 and 1601 nm are promising for laser operation, and the unusual breadth of the 1535-nm zero line makes it attractive for diode laser pumping, thus providing the potential for very small quantum defect lasing.

A study of inhomogeneous spectrum broadening in Nd3+-doped GdxY1−xVO4 (x=0, 0.37, 0.47, 0.63, and 0.83) series crystals is reported for the first time, to the best of our knowledge. Due to the random placement of the Gd and Y ions in the lattice, the spectra are inhomogeneously broadened, a result that is favorable for Q-switching and mode locking. The fluorescence lifetime and stimulated emission cross-section of the F3/24 to F11/24 and F13/24 state transitions are calculated and measured as a function of increasing x and temperature. The variation of the spectrum anisotropy is also discussed as a function of different temperature and composition values. All the results indicate that the random placement of different cations at the same lattice site is an efficient technology for the modification of emission properties that fulfill different requirements of laser applications.

A 0.3 at% Nd doped La0.11Y0.89VO4 mixed crystal was grown by the Czochralski method. The thermal properties including the thermal expansion coefficient, specific heat, thermal diffusion coefficient, and the thermal conductivity were systematically studied. Diode-pumped continuous-wave (CW) laser performance at 1.06 μm with a- and c-cut crystal were demonstrated, and the maximum output power is about 8.76 W, which is obtained at the incident power of 19.15 W. All the results show that Nd:La0.11Y0.89VO4 is an excellent crystal for application as high-power lasers. What’s more, different with the a-cut crystal, the laser spectrum of c-cut one is found to be dual-wavelength.

The thermal lens induced in an a-cut BaWO(4) crystal by stimulated Raman scattering is measured using lateral shearing interferometry. The strength of the lens is proportional to the Stokes output power. For light polarized parallel to the a-axis, and a Stokes mode radius of 120 μm, the lens is negative and highly astigmatic: -0.8 D W(-1) in the plane parallel to the a-axis and -7.7 D W(-1) in the plane parallel to the c-axis. The implications of this thermal lens for Raman laser design are discussed.

Direct sub-50-fs pulse generation is demonstrated with a mode-locked Yb:YCa4O(BO3)3 laser. With external compression, pulses as short as 35 fs are generated at 1055 nm. The oscillator operating at a repetition rate of 95 MHz is pumped by a two-section distributed Bragg reflector tapered diode laser and mode locked by a semiconductor saturable absorber mirror. The onset of self-Raman-conversion for pulse spectral bandwidths exceeding 40 nm (FWHM) is observed.

We report an efficient high-power self-frequency-doubling (SFD) Nd:GdCOB laser. The maximum output power is 3.01 W at a wavelength of 545 nm with an optical efficiency of 20.7%, which, to our knowledge, is the highest SFD laser output power and efficiency yet obtained. By optimizing the configuration and cut orientation of the Nd:GdCOB crystals, a SFD laser at a wavelength of about 530 nm was achieved with a maximum output power of 1.32 W. We propose that these SFD lasers will have promise in applications such as laser displays, medical treatment, spectroscopic analysis, etc.

We report an efficient laser-diode-pumped Tm-doped LuVO₄ crystal laser at about 1.9 μm. For the first time to our knowledge, the π-polarized Tm:LuVO₄ laser was achieved. The maximum output power and slope efficiency were 1.32 W and 28.7%, respectively. By comparison, it has been found that the a-cut Tm:LuVO₄ crystal should be more suitable for applications in high-power lasers. The central laser wavelength was observed to be located at about 1.9 μm and shifted to shorter with the increase of intracavity light intensity, which could be explained based on the reabsorption of light in the Tm:LuVO₄ crystal.

We demonstrate a cw, laser diode-pumped Nd:GdVO4/SrMoO4 crystalline Raman laser. First Stokes laser output at 1173.5 nm of 2.18 W was achieved with a diode-to-first Stokes efficiency of 8.7%. With intracavity frequency doubling in LiB3O5, 3.1 W of cw yellow emission at 586.8 nm was obtained with a 12.4% diode-to-yellow efficiency. The experimental results show that SrMoO4 is an excellent stimulated Raman scattering gain material for high-power cw near-IR Stokes and yellow lasers.

An efficient diode-pumped Yb:Y3Ga5O12 (Yb:YGG) laser was demonstrated by using a high-quality Yb:YGG crystal grown by the optical floating zone method. Continuous-wave laser power up to 2.65 W had been obtained under an incident pump power of 6.71 W at 970 nm, corresponding to an optical-to-optical efficiency of 39.5% and maximum slope efficiency of 84.5%. A modeling calculation of the Yb:YGG laser was also performed, and the theoretical results were consistent with the experimental results.

We demonstrate a passively mode-locked femtosecond laser based on the self-frequency-doubling crystal Yb:Ca4YO(BO3)3. The oscillator is pumped by a novel two-section distributed Bragg-reflector tapered diode-laser. Pulses as short as 46 fs and 42 fs at 1050 nm are achieved for the E//Z polarization without and with external compression, respectively. These are, to the best of our knowledge, the shortest pulses obtained from an oscillator based on Yb3+-doped bulk material.

Optical channel waveguides have been produced for the first time in Nd:LGS multi-functional laser crystals by using proton implantation. The obtained good guiding performance exhibits the well-confined modal fields in the waveguiding structures. The confocal fluorescence images of the obtained waveguides have revealed that the photoluminescence properties of the Nd(3+) ions have been well-preserved in the waveguide's active volume, which suggests promising applications as multi-functional integrated laser generation elements. These images have been also used to elucidate the spatial distribution of lattice damage and distortion caused by the implantation process, which are both mainly located at the nuclear collision region.

We have demonstrated what is to our knowledge the first quasi-three-level CW Nd:CLNGG laser with simple linear resonator. When the pump power was 18.2 W, a maximum output power of 1.63 W was obtained at the dual-wavelength of 935 nm and 928 nm. The optical-to-optical conversion efficiency was 9.0% and the slope efficiency was 11.5%. Lasing characteristics of a quasi-three-level CW Nd:CNGG laser were also investigated. A maximum output power of 1.87 W was obtained at the single-wavelength of 935 nm with 15.2 W pump power, corresponding to an optical-to-optical conversion efficiency of 12.3% and a slope efficiency of 15.6%.

We demonstrated efficient high-power continuous-wave (cw) and passively Q-switched disordered Nd:CLNGG laser performance. In cw operations, the output power was obtained to be 3.81 W with a slope efficiency of 30.3%. To our knowledge, they are the highest cw power and efficiency with Nd:CLNGG as the gain medium and a laser-diode (LD) as the pump source. Recorded with a spectrum analyzer, no splitting was found in the Nd:CLNGG laser, which is different with that of its isomorph Nd:CNGG. The LD pumped passively Q-switched Nd:CLNGG laser was obtained for the first time to our knowledge. The shortest pulse width, largest pulse energy and highest peak power were achieved to be 12.3 ns, 199.1 microJ and 16 kW, respectively, with Cr(4+):YAG crystals as the saturable absorbers.

We reported a dual-wavelength laser with a ceramic Nd:YAG as laser material and Cr:YAG as frequency selector and saturable absorber. Continuous-wave output power was achieved to be as high as 6.19 W at 1052 nm. With Cr:YAG, the laser has dual-wavelength at 1052 and 1064 nm. The shortest pulse width, maximum pulse energy and highest peak power were 4.8 ns, 103.2 microJ, and 21.5 kW. This pulsed laser is possible to be used as a new source to generate terahertz radiation.

A laser diode pumped Q-switched 935 nm Nd-doped Ca(3)(NbGa)(2-x)Ga(3)O(12) (Nd:CNGG) laser using a Cr,Nd:YAG crystal as a saturable absorber is demonstrated for the first time to our knowledge. An average output power of 74 mW for 935 nmQ-switched pulses and a repetition rate of 3.788 kHz are obtained. The pulse width is measured to be 26-33 ns under different pump powers. Some theoretical calculations are made to discuss the selective excitation of Nd(3+) ion in the Nd:CNGG crystal.

A nanosecond 1.3 microm Nd:YAG laser-pumped external cavity eye-safe Raman laser based on BaWO(4) crystal is efficiently demonstrated. The average power of 1.5 microm was 0.60 W operating at a pulse repetition rate of 1.7 kHz and an incident pump power of 4.14 W. Conversion efficiency of 14.5% and a high slope efficiency of 54.5% have been achieved. Pulse shortening was obviously observed. The pulse duration of the first Stokes was about 40 ns, much shorter than the fundamental pulse with a duration of approximately 220 ns.

Linearly polarized laser oscillation is observed with the isotropic disordered Yb:Ca3(NbGa)(2-x)Ga3O12 crystal, resulting from stress-induced birefringence. At high pump levels, two orthogonal polarization states exist simultaneously. A continuous-wave output power of 2.0 W is obtained with an optical-to-optical efficiency of 32%, the slope efficiency amounts to 40%. In the passively Q-switched regime, the average output power reaches 1.35 W at a pulse repetition frequency of 16.7 kHz, with a slope efficiency of 37%; the laser pulse energy, duration, and peak power amount to 81 microJ, 25 ns, and 3.24 kW, respectively.

A series of Nd:YxGd1−xVO4 (x=0.17, 0.37, 0.53, 0.63, 0.70, 0.81) mixed laser crystals with doping concentration of 0.5 at.% Nd were successfully grown by the Czochralski method. Thermal properties including the specific heat, thermal diffusion coefficient, and the thermal conductivity were systematically studied. The material constants Ms were calculated and show that the thermal fracture limit of the mixed crystals should be comparable with that of Nd:YVO4. Diode-pumped continuous-wave (CW) laser performance at 1.34 μm and 1.06 μm with a- and c-cut crystals was demonstrated. The influence of different x values on laser performance and emission cross sections was also discussed. All the results show that Nd:YxGd1−xVO4 represents a new series of crystals suitable for application as high-power diode-pumped lasers.

Efficient polarized laser oscillation along the N(g) principal optical axis is demonstrated at room temperature with a N(p)-cut Yb:KLu(WO4)2 crystal in a three-mirror folded resonator pumped by a Ti:sapphire laser at 981 nm. To our knowledge, this is the first laser study of this polarization for bulk crystals of this type. A continuous-wave output power of 0.55 W was obtained at 1044 nm for an absorbed pump power of 1.44 W, leading to optical-to-optical and slope efficiencies of 38% and 52%, respectively.

A new passively self-Q-switched Nd, Cr:GdVO(4) laser crystal was grown by Czochralski method for the first time to our knowledge. Polarized absorption spectra were measured at room temperature. The absorption bands display polarization character and an absorption band of Cr(5+) ions at 1110 nm enables the crystal to be a self-Q-switched laser material at 1.06 mum. In the passive self-Q-switching operation, the maximum output power, shortest pulse width, and largest pulse energy were obtained to be 265 mW, 230 ns, and 1.12 microJ, respectively.

We report a linear-cavity high-power all-solid-state Q-switched yellow laser. The laser source comprises a diode-side-pumped Nd:YAG module that produces 1064 nm fundamental radiation, an intracavity BaWO(4) Raman crystal that generates a first-Stokes laser at 1180 nm, and a KTP crystal that frequency doubles the first-Stokes laser to 590 nm. A convex-plane cavity is employed in this configuration to counteract some of the thermal effect caused by high pump power. An average output power of 3.14 W at 590 nm is obtained at a pulse repetition frequency of 10 kHz.

High-power continuous-wave laser operation was demonstrated with a y-cut Yb:YCa(4)O(BO(3))(3) crystal, showing critical dependence on the output coupler used. Polarized laser oscillation with E||x was obtained at 1085.6 nm by using a coupler of 0.5% transmission, yielding an output power of 7.3 W with an optical-to-optical efficiency of 63%. Higher output couplings (/=2%) led to polarized oscillation with E||z at laser wavelengths/= 1055.5 nm, the highest output power was 6.5 W. Dual-wavelength operation in the two polarization states was realized with a coupler of 1% transmission, the output powers for the two orthogonal polarizations were 3.15 W at 1084.3 nm (E||x) and 3.45 W at 1061.3 nm (E||z). The slope efficiency for output couplers with transmission in the 0.5%-2% range was 81%-83%.

Passive Q-switching operation has been demonstrated with a class of mixed Nd:Lu(x)Gd(1-x)VO(4) laser crystals. With respect to that obtained with Nd:GdVO(4), the passive Q-switching performance, including threshold, pulse energy, and peak power, was found to be greatly enhanced with the mixed vanadate crystals. The shortest pulse width of 6.2 ns, largest pulse energy of 192.5 microJ, and highest peak power of 31.1 kW were obtained at the incident pump power of 13.75 W with the mixed crystal for x=0.5.

We report the room-temperature spectroscopic properties and continuous-wave laser operation of a new disordered crystal, Yb:Ca(3)(NbGa)(2-x)Ga(3)O(12). The peak absorption cross section is 3.3x10(-20) cm(2) at 973.5 nm; the emission band important for laser action is centered at 1028 nm with a peak cross section of 2.5x10(-20) cm(2). By diode end pumping, an output power of 1.9 W was achieved with a slope efficiency of 28.5%.

An efficient and compact diode-pumped continuous-wave Yb:GdVO4 laser is demonstrated, generating an output power of 4.0 W with an optical conversion efficiency of 61% and a slope efficiency as high as 78%. With increasing pump power the polarization of the laser output changes from sigma to pi, while in a certain intermediate power range the two polarization states coexist with different emission wavelengths.

Passive mode locking of the ytterbium doped orthovanadate crystal Yb:LuVO(4) is reported for the first time. We demonstrate what we believe to be the shortest pulses directly generated with an Yb-doped crystalline laser using a semiconductor saturable absorber. The pulses at 1036 nm have a duration as short as 58 fs for an average power of 85 mW.

Barium tungstate (BaWO4) is employed to achieve efficient stimulated Raman scattering conversion in a compact diode-pumped actively Q-switched Nd:YAG laser. With an incident pump power of 9.2 W, 1.56 W of 1181 nm first-Stokes average output power was generated at a pulse repetition rate of 20 kHz, corresponding to an optical-to-optical conversion efficiency of 16.9%.

A laser-diode-array end-pumped Nd:LuVO4 crystal continuous-wave (cw) laser operating at 1.34 microm has been demonstrated. The maximum cw output power of 1.85 W was obtained at the incident pump power of 17 W for a c-cut 0.5 at. % Nd-doped LuVO4 crystal sample, giving the corresponding optical conversion efficiency of 10.88% and a slope efficiency of 13.5%. Laser experiments of Nd3+ concentration of 0.5 and 0.9 at. % a-cut crystal LuVO4 samples were also investigated; due to the strong excited-state absorption of Nd:LuVO4 at 1.34 microm, the output power was limited.

We report on the room-temperature spectroscopic properties and continuous-wave laser operation of a new Yb:LuVO4 crystal. The peak absorption cross section for the pi-polarization is 8.42 x 10(-20) cm2 at 985 nm, and the stimulated emission cross section at 1020 nm is 1.03 x 10(-20) cm2. An output power of 0.36 W at 1041 nm was obtained with a slope efficiency of 47% by use of Ti:sapphire laser pumping. With diode pumping the output power reached 1.05 W at the highest available incident pump power of 6.8 W.

Efficient cw and passively Q-switched operation with self-stimulated Raman scattering conversion was demonstrated in a compact diode-pumped Yb:KLu(WO4)2 laser. A cw output power of 3.28 W was obtained with an optical efficiency of 48.2% and a slope efficiency of 78.2% with respect to the incident pump power. Stable Q-switched operation was achieved with a Cr4+:YAG saturable absorber, generating 32.4 microJ fundamental pulses with a duration of 1.41 ns at 1030.6 nm and 14.4 microJ Raman pulses with a duration of 0.71 ns at 1137.6 nm. At an incident pump power of 7.0 W, the average output power reached 0.9 and 0.4 W for fundamental and Raman radiation, with slope efficiencies of 32.1% and 14.1%, respectively.

The absorption spectra of the 0.5at.% and 1at.% Co: LaMgAl11O19 (LaMg1-xCoxAl11O19, x=0.005 and 0.01, abbreviated as Co:LMA) crystals were measured at room temperature, and the results show that the Co: LMA crystals have two absorption bands, and the absorption band located at 1030-1660 nm can be used for a passive saturable absorber Q switch of 1.3-1.6mum laser. The passive pulsed laser output of LD-end-pumped Nd:GdVO4 1.34mum laser was demonstrated for the first time by using the 0.5 at.% Co:LMA crystal as a saturable absorber Q switch. The maximum average output power of 500 mW was obtained under the pumping power of 25 W. The shortest pulse width, the largest pulse energy and the highest peak power were obtained to be 160 ns, 25.5muJ and 150 W, respectively.

Noncollinear second-harmonic generation (SHG) in a BiB3O6 crystal was investigated. Using a picosecond Nd:YAG laser as the fundamental light source, we achieved two efficient types of noncritical noncollinear SHG. A total reflection technique was employed to make the experimental setup quite simple. The noncollinear SHG efficiency could be as high as 49.2%.

We have generated a vacuum-ultraviolet light below 160 nm by sum-frequency mixing in an optically contacted, prism-coupled KBe2BO3F2 crystal. The vacuum-ultraviolet light was generated as the fifth harmonic of a tunable, single-mode, 1-kHz Ti:sapphire laser system. The wavelength of 156 nm, to our knowledge, is the shortest ever obtained by use of nonlinear crystals in a phase-matched process. In addition, we demonstrated a 157.6-nm light source as an inspection tool for F2 laser lithography with an average power of 0.8 μW.

Received August 11, 2003 We report continuous-wave and actively Q-switched laser performance achieved with Nd:LuVO4 crystal for the 4F(3/2) --4I(1/2) transition (corresponding wavelength of 1065.8 nm) under high-power diode pumping. Continuous-wave output power of 12.55 W is obtained with an optical conversion efficiency of 50.2%. In actively Q-switched operation the average output power reaches 5.42 W at a pulse repetition frequency of 40 kHz with 18 W of pump power incident upon the crystal, yielding an optical conversion efficiency of 30.1%. The pulse energy and peak power reach 138 microJ and 16.2 kW, respectively, at a pulse repetition frequency of 25 kHz under a pump power of 14.2 W; the pulse duration is 8.5 ns.