Changqing Wang

Thermal and laser properties of Nd:YVO4 crystal

Nd:YVO 4 crystal has been grown by Czochralski method. The data of thermal expansion and specific heat have been measured. The thermal expansion coefficients along a- and c-axis are α 1 = 2.2 × 10 -6 /K, and α 3 = 8.4 × 10 -6 /K respectively. The specific heat is 24.6 cal/mol K at 330 K. The large anisotropy along c- and a-axis of thermal expansion coefficients is explained by the structure of YVO 4 crystal. 921 mW output laser at 1.06 μm has been obtained with a 3 mm × 3 mm × 1 mm crystal sample when pumped by 1840 mW cw laser diode, and the slope efficiency is 55.5%.

Growth, spectra and influence of annealing effect on laser properties of Nd:YVO4 crystal

Abstract Nd:YVO 4 single crystal has been grown by the Czochralski method. The effective segregation coefficients k eff of Nd, Y and V elements have been measured for crystals with different neodymium-doped concentrations. The absorption and fluorescence spectra of Nd:YVO 4 crystal have been measured. The lasers at 1.06 μm have been demonstrated when the crystal samples of annealed and non-annealed Nd:YVO 4 are pumped by laser diode (LD). The influence of annealing effect on laser properties is discussed.

Growth and investigation of efficient self-frequency-doubling NdxGd1−xCa4O(BO3)3 crystal

Abstract In GdCa 4 O(BO 3 ) 3 (GdCOB) crystal, the Gd 3+ ions can be substituted by Nd 3+ ions within the concentration of 0–100xa0at%. Combined laser action of the Nd 3+ ions and nonlinear optical (NLO) properties of GdCOB crystal host in the mixed Nd x Gd 1− x COB causes the crystal to become self-frequency-doubling (SFD) material. The synthesis and crystal growth of Nd x Gd 1− x COB are reported in this paper. The polarized transmittance spectra and fluorescence spectra were measured at room temperature. The strong emission peaks in the range of 850–950xa0nm are reported for the first time for the Nd x Gd 1− x COB crystal. The ( θ =66.8°, φ =132.6°) phase-matching direction was reported for the first time as the optimum phase-matching direction at 1060xa0nm by calculation and experiments whose d eff was measured and found to be 2.1xa0pm/v. The SFD experiments were carried out on 3×3×7xa0mm 3 sample with (66.8°, 132.6°) direction. The green output power at 530.5xa0nm was 192xa0mW when pumped by 1600xa0mW Tixa0:xa0sapphire tuned to 811xa0nm. The threshold was 16xa0mW. The optical–optical conversion efficiency was 12%.

Efficient self-frequency doubling of Nd:GdCOB crystal by type-I phase matching out of its principal planes

Abstract We report on the efficient self-frequency doubling of Nd:GdCOB crystal by type-I phase-matching at θ=66.3° and ϕ=134.4°, which is out of its principal planes. A CW output power of 225 mW at 530.5 nm is obtained at an absorbed pump power of 1.56 W with an optical conversion efficiency of 14.4% and an absorbed threshold pump power of 1.8 mW. To our knowledge, this is the highest output power, the highest efficiency and the lowest threshold obtained from a self-frequency-doubled Nd:GdCOB laser to date.

Growth, morphology and laser performance of Nd : YVO4 crystal

Abstract Ndxa0:xa0YVO 4 single crystal with good optical quality and large dimension has been grown by Czochralski method. The synthesizing of Ndxa0:xa0YVO 4 polycrystalline material and some problems of single crystal growth have been studied. We have developed the equilibrium shape of Ndxa0:xa0YVO 4 single crystal which is composed of {1xa00xa00} and {1xa00xa01} simple forms. The effective segregation coefficients k eff of elements have been measured and k eff of Nd element is about 0.63. The lasing at 1.06xa0μm has been demonstrated pumped by a 3xa0W laser diode (LD), and the light–light conversion efficiency is up to 50%.

Thermal, spectroscopic properties and laser performance at 1.06 and 1.33 μm of Nd : Ca4YO(BO3)3 and Nd : Ca4GdO(BO3)3 crystals

Abstract Ndxa0:xa0Ca 4 YO(BO 3 ) 3 (Ndxa0:xa0YCOB) and Ndxa0:xa0Ca 4 GdO(BO 3 ) 3 (Ndxa0:xa0GdCOB) crystals were grown by Czochralski method. Thermal expansion and specific heat of these two crystals were experimentally determined. Their fluorescence spectra were measured within the range from 1000 to 1500xa0nm. Laser output experiments at 1.06 and 1.33xa0μm of Ndxa0:xa0YCOB and Ndxa0:xa0GdCOB crystals were performed with a cw Tixa0:xa0sapphire laser as the pump source.

Growth and laser properties of Nd:Ca4YO(BO3)3 crystal

Abstract Nd:Ca 4 YO(BO 3 ) 3 (Nd:YCOB) crystal was grown by the Czochralski method, and its structure was measured by using a four circle X-ray diffractometer. The transparent spectrum from 200 to 2600 nm was measured at room temperature. The fluorescence spectrum near 1.06 μm showed that the main emission wavelength of Nd:YCOB crystal was centered at 1060.8 nm. Laser output at 1.06 μm has been demonstrated when it was pumped by a Ti:sapphire laser at the wavelength of 794 nm, the highest output power was 68 mW under pumping power of 311 mW, the pumping threshold was 163 mW and slope efficiency was 46.9%. The self-frequency doubled green light has been observed when it was pumped by a Ti:sapphire or a laser diode (LD). A 14.5 mm Nd:YCOB crystal sample cut at ( θ , φ )=(90°, 33°) was used for type I second-frequency generation (SHG) of the 1.06 μm laser pulse. The SHG conversion efficiency was 22%.

CW dual-wavelength Nd:YAG laser at 946 and 938.5 nm and intracavity nonlinear frequency conversion with a CMTC crystal

Abstract We report on the efficient CW dual-wavelength operation of a Nd:YAG laser at 946 and 938.5 nm. A total output power of 527 mW was obtained with a slope efficiency of 34%. By inserting a cadmium mercury thiocyanate (CMTC) crystal into the Nd:YAG laser cavity, frequency-doubling of 946 nm and sum-frequency-generation of 946 with 938.5 nm were realised simultaneously. Blue light at 473 and 471.1 nm with an output power of 1.6 mW was obtained. Phase matching calculations were also done for the CMTC crystal.

Laser Properties at 1.06 µm for Nd:GdVO4 Single Crystal Pumped by a High Power Laser Diode

In this letter, we report the measurements of the polarization absorption spectra, polarization emission spectra and laser properties of Nd:GdVO4 crystal. The highest output power of up to 14.25 W at 1.06 µm has been achieved with a 4 mm thick Nd:GdVO4 crystal sample when it is pumped by a 26 W cw fiber-coupled laser diode array. The light-light conversion efficiency is 54.8%. The comparing laser experiments of Nd:GdVO4 with Nd:YVO4 are also carried out by using the same laser cavity.

Efficient blue light generation from a diode laser pumped Nd:YAG laser

We report on the efficient intracavity doubling of a 946 nm Nd:YAG laser with an LBO crystal at room temperature. A CW single-ended output power of 103 mW at 473 nm is obtained at a pump power of 2.58 W with an optical conversion efficiency of 4.0%. The overall efficiency is 7.2% if blue light output from both directions is taken into account. To our knowledge, this is the highest efficiency to date for a diode laser pumped compact Nd:YAG blue laser with a simple flat-concave resonator using a bulk nonlinear crystal for intracavity doubling.