The curvature type of the thermal lens generated in a zigzag slab laser is numerically analysed. It is found that the curvature type of the thermal lens varies alternatively between the convex and the concave lenses w...The curvature type of the thermal lens generated in a zigzag slab laser is numerically analysed. It is found that the curvature type of the thermal lens varies alternatively between the convex and the concave lenses with the number of bounces of light within the slab, which can be well explained by the trace of the zigzag propagation. In addition, we conclude that the beamlet with a larger number of bounces experiences weaker thermal lensing but more serious wavefront deformation due to the large side lobe portion in the curve of optical path difference.展开更多
In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive ...In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd：YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo–optical and thermo–mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.展开更多
The paper explores the evolution of thermal behavior of the material by studying the variations in thermal diffusivity using the single beam thermal lens(TL) technique. For this purpose, the decomposition of Cu(OH)_(2...The paper explores the evolution of thermal behavior of the material by studying the variations in thermal diffusivity using the single beam thermal lens(TL) technique. For this purpose, the decomposition of Cu(OH)_(2) into CuO is studied in a time range up to 120 h, by subjecting the sample to morphological, structural, and spectroscopic characterizations. The time evolution of thermal diffusivity can be divided into three regions for demonstrating the dynamics of the reaction. When the reaction is complete, the thermal diffusivity is also found to be saturated. In addition to the morphological modifications,from rods to flakes, the variations in the amount of hydroxyl group are attributed to be responsible for the enhancement of base fluid's thermal diffusivity by 165%. Thus the study unveils the role of hydroxyl groups in the thermal behavior of CuO.展开更多
A novel method for the determination of cationic surfactant by laser thermal lens spectrometry was developed. It was based on the reaction between 1-hydroxy-2-(5-nitro-2-Pyri- dylazo)-8-aminonaphthalene-3,6-disulfoni...A novel method for the determination of cationic surfactant by laser thermal lens spectrometry was developed. It was based on the reaction between 1-hydroxy-2-(5-nitro-2-Pyri- dylazo)-8-aminonaphthalene-3,6-disulfonic acid (5-NO2-PAH) and cationic surfactant to form 1:2 ionic association complex in a weakly basic medium (pH 9.44). The determination conditions and the mechanism were discussed. The method has been applied to the analysis of wastewater and moat water samples.展开更多
A new method for the determination of utratrace silver(I) by near field thermal lens spectrometry has been developed. This method is based on the silver(I) catalyzed discoloring reaction of bromocresol green oxidized...A new method for the determination of utratrace silver(I) by near field thermal lens spectrometry has been developed. This method is based on the silver(I) catalyzed discoloring reaction of bromocresol green oxidized by sodium persulphate in the presence of a, a-bipy as activator and Triton X-100 as sensitizer. The linear range of this method is 0~1.6 ng穖L-1 of silver. The detection limit is 2?0-2 ng穖L-1. The method has been applied to the determination of silver in lead power and photographic paper with satisfactory results.展开更多
The paper employs the principles of graph theory in nanobiophotonics, where the soot-assisted intra-pigmental energy transport in leaves is unveiled through the laser-induced thermal lens(TL) technique. Nanofluids wit...The paper employs the principles of graph theory in nanobiophotonics, where the soot-assisted intra-pigmental energy transport in leaves is unveiled through the laser-induced thermal lens(TL) technique. Nanofluids with different soot concentrations are sprayed over Lablab purpureus(L) sweet leaves, and the extracted pigments are analyzed. The graph features of the constructed complex network from the TL signal of the samples are analyzed to understand their variations with optical absorbance. Besides revealing the presence of optimum soot concentration that can enhance photosynthesis,the study brings out the potential application of graph features in nanobiophotonics.展开更多
Nonlinear refractive properties of chloroaluminum phthalocyanine （CAP） in ethanol solution are studied using the Z-scan technique with picosecond （ps） and nanosecond （ns） laser pulses at a wavelength of 532nm. A...Nonlinear refractive properties of chloroaluminum phthalocyanine （CAP） in ethanol solution are studied using the Z-scan technique with picosecond （ps） and nanosecond （ns） laser pulses at a wavelength of 532nm. A transition from self-focusing to self-defocusing in CAP solution excited by 10 ns pulses is observed during the decrease of its concentration.This transition is due to co-existing excited-state refraction and transient thermal lensing effects.The experimental results are described very well using the rate-equation model and the theory of transient thermal refraction in liquids.The refractive cross sections of the excited-state are also obtained.展开更多
Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the l...Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the liquid induced by laser heating,i.e.,thermal lens effect,which changes the refractive index locally and thus the optical path difference.The up-down asymmetry of the interference rings is caused by convection in the liquid.With the increase of the viscosity,the interference rings change their shape from oval to circular shape.After a shutter is opened and the laser shines into the liquid,the interference rings are circular at the beginning.As time goes on,they gradually turn into an oval shape.Let the liquid go a free-fall at the beginning,the interference rings remain circular.All the three experiments have confirmed that the asymmetric interference rings are due to convection in the liquid associated with thermal lens effect.We also numerically simulate the two-dimensional heat conduction with and without convection,whose results agree well with our experimental observations.展开更多
A selective and sensitive method for determination of platinum and palladium(II) in an aqueous solution simultaneously by laser thermal lens spectrometry, based on the complex reaction of 2-(3,5-dichloropyridylazo)-5-...A selective and sensitive method for determination of platinum and palladium(II) in an aqueous solution simultaneously by laser thermal lens spectrometry, based on the complex reaction of 2-(3,5-dichloropyridylazo)-5-dimethylaminoamiline (3,5-diCl-PA^D~MA) with platinum and palladium, has been developed. It is shown that the palladium complex can be formed at room temperature, while the platinum complex can be only formed after being heated in a boiling water bath. By using this difference of reaction temperature and the characteristic of the complexes mentioned above, the method for simultaneous determination of platinum and palladium was established in an aqueous solution without a pre-separation. The results show that the dynamic linear ranges of determination for platinum and palladium are 0.005- 0.04 μg/mL and 0.005- 0.25 μg/mL respectively, and that the detection limits are both 0.002 μg/mL. The method has been applied to the determination of platinum and palladium simultaneously in alloy and catalyst samples with satisfactory results.展开更多
A new method for the determination of ultratrace silver(I) by near field laser thermal lens spectrometry has been developed. This method is based on the silver(I) catalyzed discoloring reaction of bromcresol green oxi...A new method for the determination of ultratrace silver(I) by near field laser thermal lens spectrometry has been developed. This method is based on the silver(I) catalyzed discoloring reaction of bromcresol green oxidized by so-dium persulfate in the presence of ,'-bipyridine as an activator and TritonX-100 as a sensitizer. The reaction mechanism was discussed. The linear range of the method is 0—1.6 ngmL-1 and the detection limit is 2×10-2 ngmL-1 for silver. The method has been applied to the determination of silver in lead powder and photographic paper with satisfactory results.展开更多
We have numerically analyzed the thermal effects in Nd： YLF laser rod. The calculations of temperature and stress distributions in the Nd： YLF laser rod were performed with finite element （FE） simulations. The cal...We have numerically analyzed the thermal effects in Nd： YLF laser rod. The calculations of temperature and stress distributions in the Nd： YLF laser rod were performed with finite element （FE） simulations. The calculations showed that the laser rod could be pumped up to a power of 40 W without fracture caused by thermal stress. The calculated thermal lens power of thermally induced lens in Nd： YLF （o--polarization） laser rod was analyzed and validated experimentally with two independent techniques. A Shack-Hartmann wavefront sensor and a Mach-Zehnder interferometer were used for direct measurements of focal thermal lens at different pump powers. The obtained measurements were coinciding with the FE simulations.展开更多
The effect of different kinds of surfactants on the extraction process of Nile Blue-I was investigated by laser thermal lens spectrometry. It was shown that the surfactants could accelerate or decelerate the extractio...The effect of different kinds of surfactants on the extraction process of Nile Blue-I was investigated by laser thermal lens spectrometry. It was shown that the surfactants could accelerate or decelerate the extraction rate by varying the extractive's solubility and the intrafacial tension of the extraction solution. The higher the concentration of surfactants was, the more obvious the effect.展开更多
This study develops a Yb:KGW dual-crystal based regenerative amplifier.The thermal lensing and gain-narrowing effects are compensated by the dual-crystal configuration.Sub-nanojoule pulses are amplified to 1.5 mJ with...This study develops a Yb:KGW dual-crystal based regenerative amplifier.The thermal lensing and gain-narrowing effects are compensated by the dual-crystal configuration.Sub-nanojoule pulses are amplified to 1.5 mJ with 9 nm spectral bandwidth and 1 kHz repetition rate using chirped pulse amplification technology.Consequently,1.2 m J pulses with a pulse duration of 227 fs are obtained after compression.Thanks to the cavity design,the output laser was a near diffraction limited beam with M2 around 1.1.The amplifier has the potential to boost energy above 2 m J after compression and act as a front end for a future kilohertz terawatt-class diode-pumped Yb:KGW laser system.展开更多
A simple,compact,double-pass pumped Nd:YVO4 thin disk laser is demonstrated.Its continuous-wave performance with different Nd doping concentrations and thicknesses is investigated experimentally.The maximum output pow...A simple,compact,double-pass pumped Nd:YVO4 thin disk laser is demonstrated.Its continuous-wave performance with different Nd doping concentrations and thicknesses is investigated experimentally.The maximum output power of 17.7 W is achieved by employing a 0.5 at.%doped sample,corresponding to an optical-to-optical efficiency of 46% with respect to the absorbed pump power.In addition,a numerical analysis and an experimental study of the temperature distribution,and thermal lens effect of the Nd:YVO4 thin disk,are presented considering the influence of the energy transfer upconversion effect and the temperature dependence of the thermal conductivity tensor.The simulated results are in good agreement with the experimental results.展开更多
We demonstrate a continuous-wave(CW)Nd:YVO_(4)-potassium gadolinium tungstate(KGW)intracavity Raman laser with a diode-to-Stokes optical efficiency of 34.2%.By optimizing the cavity arrangement and reducing the cavity...We demonstrate a continuous-wave(CW)Nd:YVO_(4)-potassium gadolinium tungstate(KGW)intracavity Raman laser with a diode-to-Stokes optical efficiency of 34.2%.By optimizing the cavity arrangement and reducing the cavity losses,8.47 W Stokes output at 1177 nm was obtained under an incident 878.6 nm diode pump power of 24.8 W.The influence of cavity losses on the power and efficiency of the CW Raman laser,as well as the potential for further optimization,was investigated based on the numerical model.The observation of thermally-induced output rollover was well explained by the calculation of the thermal lensing and cavity stability,indicating that the end-face curvature played an important role when the end-face of the crystal was highly reflective coated to make the cavity.A 10.9 W Stokes output under 40.9 W incident pump was also demonstrated with a cavity arrangement less sensitive to the end-face curvature,which is the highest output power of CW intracavity Raman lasers reported.展开更多
In this paper we report a compact and robust regenerative amplifier developed as the pump laser for a high repetition rate terahertz parametric amplifier.With properly chosen pump source and carefully designed cavity...In this paper we report a compact and robust regenerative amplifier developed as the pump laser for a high repetition rate terahertz parametric amplifier.With properly chosen pump source and carefully designed cavity,Nd∶YVO4 crystal,and laser beam collimator,a maximum output pulse energy of 480μJ has been achieved at the repetition rate of 10 kHz.The output laser has a nearly Gaussian transverse profile and a narrow bandwidth of 0.2 nm.Longterm monitoring shows an root mean square power fluctuation of about 1%.These characteristics satisfy all requirements for high repetition rate terahertz parametric amplifier.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.50721004 and 60978032)
文摘The curvature type of the thermal lens generated in a zigzag slab laser is numerically analysed. It is found that the curvature type of the thermal lens varies alternatively between the convex and the concave lenses with the number of bounces of light within the slab, which can be well explained by the trace of the zigzag propagation. In addition, we conclude that the beamlet with a larger number of bounces experiences weaker thermal lensing but more serious wavefront deformation due to the large side lobe portion in the curve of optical path difference.
文摘In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd：YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo–optical and thermo–mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.
文摘The paper explores the evolution of thermal behavior of the material by studying the variations in thermal diffusivity using the single beam thermal lens(TL) technique. For this purpose, the decomposition of Cu(OH)_(2) into CuO is studied in a time range up to 120 h, by subjecting the sample to morphological, structural, and spectroscopic characterizations. The time evolution of thermal diffusivity can be divided into three regions for demonstrating the dynamics of the reaction. When the reaction is complete, the thermal diffusivity is also found to be saturated. In addition to the morphological modifications,from rods to flakes, the variations in the amount of hydroxyl group are attributed to be responsible for the enhancement of base fluid's thermal diffusivity by 165%. Thus the study unveils the role of hydroxyl groups in the thermal behavior of CuO.
文摘A novel method for the determination of cationic surfactant by laser thermal lens spectrometry was developed. It was based on the reaction between 1-hydroxy-2-(5-nitro-2-Pyri- dylazo)-8-aminonaphthalene-3,6-disulfonic acid (5-NO2-PAH) and cationic surfactant to form 1:2 ionic association complex in a weakly basic medium (pH 9.44). The determination conditions and the mechanism were discussed. The method has been applied to the analysis of wastewater and moat water samples.
文摘A new method for the determination of utratrace silver(I) by near field thermal lens spectrometry has been developed. This method is based on the silver(I) catalyzed discoloring reaction of bromocresol green oxidized by sodium persulphate in the presence of a, a-bipy as activator and Triton X-100 as sensitizer. The linear range of this method is 0~1.6 ng穖L-1 of silver. The detection limit is 2?0-2 ng穖L-1. The method has been applied to the determination of silver in lead power and photographic paper with satisfactory results.
文摘The paper employs the principles of graph theory in nanobiophotonics, where the soot-assisted intra-pigmental energy transport in leaves is unveiled through the laser-induced thermal lens(TL) technique. Nanofluids with different soot concentrations are sprayed over Lablab purpureus(L) sweet leaves, and the extracted pigments are analyzed. The graph features of the constructed complex network from the TL signal of the samples are analyzed to understand their variations with optical absorbance. Besides revealing the presence of optimum soot concentration that can enhance photosynthesis,the study brings out the potential application of graph features in nanobiophotonics.
基金Project supported by the National Natural Science Fundation of China (Grant No 10104007)the Program for New Century Excellent Talents in University,China (Grant No NCET-04-0333)the Excellent Youth Fund of Heilongjiang Province,China(Grant No JC-04-04)
文摘Nonlinear refractive properties of chloroaluminum phthalocyanine （CAP） in ethanol solution are studied using the Z-scan technique with picosecond （ps） and nanosecond （ns） laser pulses at a wavelength of 532nm. A transition from self-focusing to self-defocusing in CAP solution excited by 10 ns pulses is observed during the decrease of its concentration.This transition is due to co-existing excited-state refraction and transient thermal lensing effects.The experimental results are described very well using the rate-equation model and the theory of transient thermal refraction in liquids.The refractive cross sections of the excited-state are also obtained.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0301202)the National Natural Science Foundation of China(Grant Nos.11674311 and U20A20205)。
文摘Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the liquid induced by laser heating,i.e.,thermal lens effect,which changes the refractive index locally and thus the optical path difference.The up-down asymmetry of the interference rings is caused by convection in the liquid.With the increase of the viscosity,the interference rings change their shape from oval to circular shape.After a shutter is opened and the laser shines into the liquid,the interference rings are circular at the beginning.As time goes on,they gradually turn into an oval shape.Let the liquid go a free-fall at the beginning,the interference rings remain circular.All the three experiments have confirmed that the asymmetric interference rings are due to convection in the liquid associated with thermal lens effect.We also numerically simulate the two-dimensional heat conduction with and without convection,whose results agree well with our experimental observations.
基金ProjectsupportedbytheNaturalScienceFoundationofShaanxiProvinceofChina (No .97H0 1) .
文摘A selective and sensitive method for determination of platinum and palladium(II) in an aqueous solution simultaneously by laser thermal lens spectrometry, based on the complex reaction of 2-(3,5-dichloropyridylazo)-5-dimethylaminoamiline (3,5-diCl-PA^D~MA) with platinum and palladium, has been developed. It is shown that the palladium complex can be formed at room temperature, while the platinum complex can be only formed after being heated in a boiling water bath. By using this difference of reaction temperature and the characteristic of the complexes mentioned above, the method for simultaneous determination of platinum and palladium was established in an aqueous solution without a pre-separation. The results show that the dynamic linear ranges of determination for platinum and palladium are 0.005- 0.04 μg/mL and 0.005- 0.25 μg/mL respectively, and that the detection limits are both 0.002 μg/mL. The method has been applied to the determination of platinum and palladium simultaneously in alloy and catalyst samples with satisfactory results.
基金Project supported by the Science Foundation (No. 99H07) of Shaanxi Province of China.
文摘A new method for the determination of ultratrace silver(I) by near field laser thermal lens spectrometry has been developed. This method is based on the silver(I) catalyzed discoloring reaction of bromcresol green oxidized by so-dium persulfate in the presence of ,'-bipyridine as an activator and TritonX-100 as a sensitizer. The reaction mechanism was discussed. The linear range of the method is 0—1.6 ngmL-1 and the detection limit is 2×10-2 ngmL-1 for silver. The method has been applied to the determination of silver in lead powder and photographic paper with satisfactory results.
文摘We have numerically analyzed the thermal effects in Nd： YLF laser rod. The calculations of temperature and stress distributions in the Nd： YLF laser rod were performed with finite element （FE） simulations. The calculations showed that the laser rod could be pumped up to a power of 40 W without fracture caused by thermal stress. The calculated thermal lens power of thermally induced lens in Nd： YLF （o--polarization） laser rod was analyzed and validated experimentally with two independent techniques. A Shack-Hartmann wavefront sensor and a Mach-Zehnder interferometer were used for direct measurements of focal thermal lens at different pump powers. The obtained measurements were coinciding with the FE simulations.
基金Project (No. 97H01) supported by the Science Foundation of Shanxi Province of China
文摘The effect of different kinds of surfactants on the extraction process of Nile Blue-I was investigated by laser thermal lens spectrometry. It was shown that the surfactants could accelerate or decelerate the extraction rate by varying the extractive's solubility and the intrafacial tension of the extraction solution. The higher the concentration of surfactants was, the more obvious the effect.
基金supported by the Natural Science Foundation of Top Talent of SZTU(Nos.2019010801001 and 202024555101039)。
文摘This study develops a Yb:KGW dual-crystal based regenerative amplifier.The thermal lensing and gain-narrowing effects are compensated by the dual-crystal configuration.Sub-nanojoule pulses are amplified to 1.5 mJ with 9 nm spectral bandwidth and 1 kHz repetition rate using chirped pulse amplification technology.Consequently,1.2 m J pulses with a pulse duration of 227 fs are obtained after compression.Thanks to the cavity design,the output laser was a near diffraction limited beam with M2 around 1.1.The amplifier has the potential to boost energy above 2 m J after compression and act as a front end for a future kilohertz terawatt-class diode-pumped Yb:KGW laser system.
基金Ministry of Science and Technology of the People's Republic of China(MOST)(2016YFB1102402,2017YFB0405202)Key Laboratory of Opto-electronic Information Technology,Ministry of Education(Tianjin University),China(2019KFKT003)Shanghai Science and Technology Achievements Transformation and Industrialization project(18511109800).
文摘A simple,compact,double-pass pumped Nd:YVO4 thin disk laser is demonstrated.Its continuous-wave performance with different Nd doping concentrations and thicknesses is investigated experimentally.The maximum output power of 17.7 W is achieved by employing a 0.5 at.%doped sample,corresponding to an optical-to-optical efficiency of 46% with respect to the absorbed pump power.In addition,a numerical analysis and an experimental study of the temperature distribution,and thermal lens effect of the Nd:YVO4 thin disk,are presented considering the influence of the energy transfer upconversion effect and the temperature dependence of the thermal conductivity tensor.The simulated results are in good agreement with the experimental results.
基金This work was supported by the National Natural Science Foundation of China(Nos.61975146,62105240,62075159,and 62275190)the Shandong Province Key R&D Program(Nos.2020CXGC010104 and 2021CXGC010202)the Seed Foundation of Tianjin University(No.2023XPD-0020).
文摘We demonstrate a continuous-wave(CW)Nd:YVO_(4)-potassium gadolinium tungstate(KGW)intracavity Raman laser with a diode-to-Stokes optical efficiency of 34.2%.By optimizing the cavity arrangement and reducing the cavity losses,8.47 W Stokes output at 1177 nm was obtained under an incident 878.6 nm diode pump power of 24.8 W.The influence of cavity losses on the power and efficiency of the CW Raman laser,as well as the potential for further optimization,was investigated based on the numerical model.The observation of thermally-induced output rollover was well explained by the calculation of the thermal lensing and cavity stability,indicating that the end-face curvature played an important role when the end-face of the crystal was highly reflective coated to make the cavity.A 10.9 W Stokes output under 40.9 W incident pump was also demonstrated with a cavity arrangement less sensitive to the end-face curvature,which is the highest output power of CW intracavity Raman lasers reported.
文摘In this paper we report a compact and robust regenerative amplifier developed as the pump laser for a high repetition rate terahertz parametric amplifier.With properly chosen pump source and carefully designed cavity,Nd∶YVO4 crystal,and laser beam collimator,a maximum output pulse energy of 480μJ has been achieved at the repetition rate of 10 kHz.The output laser has a nearly Gaussian transverse profile and a narrow bandwidth of 0.2 nm.Longterm monitoring shows an root mean square power fluctuation of about 1%.These characteristics satisfy all requirements for high repetition rate terahertz parametric amplifier.
