Mixed Laser Crystal Research Articles

The growth and spectroscopic properties of Yb:KNGM crystal: A promising ultrashort pulse laser material

Yb3+-doped mixed laser crystals are widely recognized as materials capable of generating ultrashort pulses and have garnered significant attention in recent times. In this study, we thoroughly examined the structure and spectroscopic properties of a novel mixed molybdate crystal, Yb:KNGM. Notably, we made detailed observations of an exceptionally broad absorption band with a full width at half maximum (FWHM) of 78 nm. The broad absorption band indicates that the commercially available InGaAs laser diode (LD) can be effectively utilized for high pumping efficiency purpose. The absorption and emission cross-section at 967 and 1014 nm were calculated to be 1.56 × 10−20 cm2 and 2.05 × 10−20 cm2, respectively. The FWHM of the emission band reaches a substantial range of 62 nm, making it highly conducive to the production of ultrashort pulse lasers. The bandgap (Eg) was fitted as 3.26 eV by Tauc formula. Positive gain cross-section can be achieved while the β is only higher than 0.2 and a large FWHM of 41 nm was discovered when β is 0.5. The aforementioned merits provide compelling evidence that Yb:KNGM crystal holds great promise as a laser crystal for the application of wild tunable and ultrashort pulse lasers pumped by LD.

Investigation of defect, mechanical, thermal properties and refractive index on an Er:LuYSGG mixed laser crystal

We investigate the defect, mechanical, thermal properties, and refractive index of Er:LuYSGG mixed crystal grown by the Czochralski method. The chemical etching pit patterns present a regular tetrahedron, which consists well with the corresponding atomic arrangement schematics. The Mohs hardness is obtained to be 6.60. The thermal expansion coefficient and the thermal conductivity along <111> crystallographic orientation are achieved to be 7.91 × 10−6 K−1 and 3.423 W m−1 K−1, respectively, indicating the Er:LuYSGG has a relatively high damage threshold. Based on the measured values of refractive index, the Sellmeier equation is fitted and the refractive index curve in the range of 400–3000 nm is displayed. All these results are of great significance for the further research and laser application of Er:LuYSGG crystal.

Growth and spectroscopic properties of Yb0.1Gd1.8La0·1SiO5 crystal: A promising new laser material for ultrashort laser

Recently, in the field of femtosecond lasers, an intense interest has been aroused for Yb3+-doped laser crystals which are able to be pumped directly by semiconductor laser. In this work, a novel Yb3+-doped mixed laser crystal Yb0.1Gd1.8La0·1SiO5 (Yb:GLSO) crystal with high-quality was grown successfully by Czochralski method. Raman spectrum confirmed that the Yb:GLSO has highly disordered crystal structure. The large absorption cross section (0.70 × 10−20 cm2) of Yb:GLSO crystal at around 975 nm indicates the crystal can be pumped efficiently by the commercialized InGaAs laser diode. The stimulated emission cross section at 1030 nm was calculated to be 0.7 × 10−20 cm2 and the bandwidth of the emission peak was determined as high as 175 nm. Positive gain cross sections were appeared at 1030, 1045 and 1088 nm when inversion ratio higher than 0.2. All these results suggest that Yb:GLSO crystal is a very promising novel laser material for realizing tunable solid-state and ultra-short pulsed lasers with LD pumping.

Spectroscopic properties of Nd:Gd0.89La0.1NbO4 mixed laser crystal

A Nd-doped niobate mixed laser crystal of Nd0.01:Gd0.89La0.1NbO4 (Nd:GLNO) has been grown successfully by Czochralski method. The absorption spectrum, fluorescence spectrum and fluorescence decay curve of Nd:GLNO crystal were measured at room temperature. The spectral parameters of Nd:GLNO crystal were obtained based on Judd-Ofelt (J-O) theory calculation. The three intensity parameters Ωt(t=2, 4, 6) were calculated to be 6.61, 1.43 and 3.31 × 10–20 cm2, respectively. On the base of the Ωt calculation, the branching ratios, spontaneous radiative probabilities, radiative lifetime and fluorescence quantum efficiency of the 4F3/2 level have been evaluated. Compared with other Nd-doped niobate laser crystal, Nd:GLNO shows a special spectral properties due to the large structure disorder caused by La3+. All the results demonstrate that this crystal is a specific low symmetrical laser material different from other niobates family crystals such as Nd:GdNbO4 (Nd:GNO) and Nd:YNbO4 (Nd:YNO) and can be considered as a promising laser material suitable for laser diode pumping.

Crystal growth, structure, defects, mechanical and spectral properties of Nd0.01:Gd0.89La0.1NbO4 mixed crystal

A novel mixed laser crystal of Nd:GdLaNbO4 (Nd:GLNO) was grown successfully by conventional Czochralski method. The unit cell parameters were obtained by Rietveld refinement method. The density of the as-grown crystal was measured by Archimedean buoyancy method and calculated in theory. Absorption spectrum of Nd:GLNO crystal was recorded at room temperature, and 11 absorption peaks were assigned. The defects of Nd:GLNO crystal were revealed by using chemical etching method with phosphoric acid as etchant. The mechanical properties (including hardness, yield strength, elastic stiffness constant, fracture toughness and brittleness index) were systemically estimated based on Vickers hardness test. All these obtained results play a quite important role in further investigation of Nd:GLNO crystal.

Crystal growth and characterization of a mixed laser crystal: Nd-doped Gd0.89La0.1NbO4

A Nd:GdLaNbO4 crystal was grown successfully by the Czochralski method and a CW laser was realized with a slope efficiency of 34.2%.

Crystal growth, defects, and mechanical and spectral properties of a novel mixed laser crystal Nd:GdYNbO4

A mixed laser crystal of Nd-doped GYNO crystal was grown successfully by Czochralski method. The crystal belongs to monoclinic system with space group I2/a, the structural parameters are obtained by the X-ray Rietveld refinement method. The defects and dislocations along three crystallographic orientations were studied by using the chemical etching method with the phosphoric acid etchant. The mechanical properties (including hardness, yield strength, fracture toughness, and brittle index) of the crystal were estimated by Vickers hardness test. The transmission spectrum was measured at room temperature, and the absorption peaks were assigned. Spectral properties of the as-grown crystal were investigated by Judd–Ofelt theory, and the Judd–Ofelt intense parameters Ω2,4,6 were obtained to be 9.674 × 10−20, 2.092 × 10−20, and 4.061 × 10−20 cm2, respectively.

Crystal growth, spectral properties and continuous wave laser operation of new mixed Nd:GdYNbO4 laser crystal

A new mixed laser crystal Nd:Gd0.69Y0.3NbO4 (Nd:GYNO) with high quality was grown successfully by Czochralski method. Its structure parameters are obtained by the X-ray Rietveld refinement method. The effective segregation coefficient of Nd3+ ions is 0.61 in GYNO host. The maximum absorption cross section at 809 nm and peak emission cross section at 1065.6 nm of Nd:GYNO crystal are 11.6 × 10−20 and 20.5 × 10−20 cm2, respectively. The fluorescence lifetime of 4F3/2 manifold for Nd3+ in Nd:GYNO crystal is fitted to be 156 μs. Diode-pumped continuous-wave laser operations at 1.06 μm with Nd:GYNO crystals cut perpendicular to crystallographic a, b, and c axes (denoted as a-, b- c-cut, respectively) were demonstrated. A maximum output power of 0.98 W was obtained with c-cut crystal, corresponding to an optical-to-optical conversion efficiency of 31.3% and a slope efficiency of 30.4%. All these results imply that the Nd:GYNO crystal has great potential application in low and even moderate lasers.

The growth and dislocation characterization of Yb0.005Y0.848Lu0.147VO4 mixed laser crystal

A new mixed laser crystal, Yb0.005Y0.848Lu0.147VO4, has been successfully grown using the Czochralski method. An ICP‐OES was used to measure the concentrations of elements (Yb, Y, Lu, V) in the crystal, and the chemical formula was determined. X‐ray powder diffraction analysis shows that the crystal has ZrSiO4 structure. A pair of edge dislocations with certain orientation was observed by the HREM, and the orientation was confirmed by the calibration of the diffraction spots. The formation mechanism of this type dislocation was given by analysis on structure and thermal expansion of crystal. The suggestion to avoid these dislocations was also given.

Synthesis, growth, defects and laser action of Yb:Y0.71Lu0.29VO4 crystals

A new promising mixed laser crystal of the composition Yb:Y0.79Lu0.21VO4 was grown and realized, achieving a continuous-wave laser output.

Passively Q-switched laser performance of an a-cut Nd:Lu0.33Y0.36Gd0.3VO4 crystal at 1.34 μm with V3+:YAG as the saturable absorber

Continuous-wave and passively Q-switched (PQS) laser characteristics at 1.34 μm of a novel a-cut three matrix mixed laser crystal Nd:Lu0.33Y0.36Gd0.3VO4 with V3+:YAG as the saturable absorber were demonstrated. The maximum output power of 1.21 W was obtained at the pump power of 6.34 W, corresponding to an optical conversion efficiency of 19.1% and a slope efficiency of 23.5%. For the PQS operation at 1.34 μm, the minimum pulse width attained was 72.7-ns, with the pulse repetition rate of 103 kHz, with the single pulse energy and peak power estimated to be 5.18 μJ and 71.3 W, respectively.

Growth and Thermal Characterization of Yb:Y&lt;sub&gt;0.923&lt;/sub&gt;Lu&lt;sub&gt;0.071&lt;/sub&gt;VO&lt;sub&gt;4&lt;/sub&gt;

A new mixed laser crystal, Yb0.006Y0.923Lu0.071VO4, has been successfully grown using the Czochralski method. X-ray powder diffraction analysis shows that the crystal has ZrSiO4 structure. Density, thermal expansion coefficients, specific heat and thermal diffusion coefficients were measured, and the thermal conductivity coefficients were determined.

Growth, structure and laser action of Yb:YxLu1−xVO4 (x = 0.93, 0.85 and 0.71) mixed crystals

A new series of Yb:YxLu1−xVO4 (x=0.93, 0.85, and 0.71) mixed laser crystals were grown by the Czochralski method. Crystal structure analysis showed that Yb:YxLu1−xVO4 crystals possessed the similar crystal structure to those of the tetragonal YVO4 and LuVO4. The polarized absorption spectra were measured at room temperature. The continuous-wave (CW) laser action of diode-pumped Yb:YxLu1−xVO4 mixed crystal laser was reported. A maximum output power of 1.19W with a slope efficiency of 21.2% was demonstrated for the Yb:Y0.93Lu0.07VO4 crystal. The laser emission spectra and relationship curves between the output power and absorbed pump power (Pabs) of Yb:YxLu1−xVO4 (x=0.93 and 0.71) crystals were measured. The laser damage threshold values and the optical quality of Yb:YxLu1−xVO4 mixed crystal were also studied.

Continuous-wave and Q-switched laser performance of Nd:Lu0.99La0.01VO4 mixed crystals at 1.06 μm

We report continuous-wave (CW) and actively Q-switched laser performance achieved with an uncoated mixed laser crystal Nd:Lu0.99La0.01VO4 at 1065.655nm end-pumped by a laser-diode-array. The maximum CW output power of 6.26W was obtained with the optical conversion efficiency of 31.3%. For the Q-switching operation, a maximum average output power of 6.06W was obtained at the pulse repetition frequency (PRF) of 90kHz, yielding an optical conversion efficiency of 30.3%. The highest pulse energy and highest peak power obtained were 954μJ and 63.8kW at the PRF of 5kHz, respectively.

Thermal, spectroscopic, and laser characterization of Nd:LuxY1-xVO4 series crystals

A series of Nd:LuxY1-xVO4 (x = 0.10, 0.26, 0.41, 0.61, 0.67, 0.80) mixed laser crystals were grown and researched systematically, for the first time to our knowledge. Their thermal properties were investigated, including the specific heat, thermal expansion, thermal conductivity and the material constant. Their spectral properties were measured and their spectral parameters were calculated by J-O theory, including the absorption spectrum, emission spectrum, fluorescence lifetime and emission cross section. In CW laser operation, a maximum output power of 3.1 W was obtained from the Nd:Lu0.10Y0.90VO4 mixed crystal, corresponding to an optical conversion efficiency of 51.7 %, and a slope efficiency of 59.8 %. When Cr:YAG crystal was used as the saturable absorber, passively Q-switched pulse laser operation was achieved for Nd:LuxY1-xVO4 series crystals. The best pulse performance came from Nd:Lu0.10Y0.90VO4 crystal, with the maximum pulse energy of 169 μJ and the highest peak power of 26.4 kW.

Growth and laser characterization of a mixed laser crystal Nd: Lu 0.141Y 0.855VO 4

A new Nd: Lu 0.141Y 0.855VO 4 mixed laser crystal had been successfully grown by the Czochralski method. The reason of the crystal boule appearing additionally yellowish at the bottom was discussed. The X-ray powder diffraction analysis showed that the as-grown mixed crystal possesses the ZrSiO 4 structure. The effective segregation coefficients of Nd 3+ and Lu 3+ ions in the crystal were measured to be about 0.51 and 0.76, respectively. The room temperature fluorescence spectrum of the mixed crystal showed that the FWHM (full-width at half-maximum) of the 1064.9 nm fluorescence band was 5.1 nm, broader than that of Nd: YVO 4. A continuous-wave (CW) laser output was achieved with the Nd: Lu 0.141Y 0.855VO 4 crystal at 1.06 μm using laser diode pumping. The maximum CW output power of 1.7 W was obtained with the pump power of 7.6 W, higher than the 1.38 W achieved with the 0.5 at% Nd: LuVO 4 crystal under the same experimental conditions. All the results above show that the Nd: Lu 0.141Y 0.855VO 4 crystal is a promising laser material.

Growth and characterization of Nd:Y_xGd_1−xVO_4 series laser crystals

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.

Growth and laser characterization of mixed Nd:Lu xGd 1−xVO 4 laser crystals

A new series Nd:Lu x Gd 1− x VO 4 ( x=0.14, 0.32, 0.50, 0.61, 0.70 and 0.80) mixed laser crystals have been successfully grown by the Czochralski method. The X-ray powder diffraction (XRPD) analysis shows that the as-grown mixed crystals possess the ZrSiO 4 structure. The cell parameters are found to decrease with an increase of x. The optical absorption spectra of the mixed crystals have been measured at room temperature, and five strong-absorption bands centered at the wavelengths of 531, 594, 752, 807 and 880 nm have been revealed in all crystals. They are assigned to the different spin- and electric-dipole-allowed transition from the ground state to the 2K 13/2+ 4G 7/2+ 4G 9/2, 4G 5/2+ 2G 7/2, 4F 7/2+ 4S 3/2, 4F 5/2+ 2H 9/2 and 4F 3/2 energy levels, respectively. A continuous-wave (CW) laser output has been achieved with the mixed crystals at 1.06 μm under laser diode pumping. The maximum CW output power of 377.4 mW has been obtained with the pump power of 2 W, and the corresponding optical conversion efficiency is 18.8%.

Growth and Q-switching performance on mixed laser crystal Nd 0.0055(Gd 0.64Y 0.36) 0.9945VO 4

A Nd 0.0055(Gd 0.64Y 0.36) 0.9945VO 4 mixed laser crystal has been successfully grown by the Czochralski method. Properties of this crystal have been introduced. Formed with a simple concave-plano resonator, passive Q-switching operation of a diode-pumped Nd 0.0055(Gd 0.64Y 0.36) 0.9945VO 4 laser with Cr 4+:YAG has been demonstrated. For the Q-switched operation, the maximum average power was measured to be 1.11 W with a corresponding pulse repetition rate of 10 kHz and a Q-switched pulse duration of 7.6 ns. The largest single Q-switched pulse energy of 111 μJ and the highest peak power of 14.61 kW have been obtained in the laser.