Continuous-wave radiation of 5W at 532 nm was produced with an Nd:YVO_(4)/KTP intracavity&equency-doubled laser end-pumped by a diode-laser-array at pump power of 17.2 W,giving optical conversion efRciency of 29.1...Continuous-wave radiation of 5W at 532 nm was produced with an Nd:YVO_(4)/KTP intracavity&equency-doubled laser end-pumped by a diode-laser-array at pump power of 17.2 W,giving optical conversion efRciency of 29.1%.The output power stability was measured to be better than 1.5%in short term operation.The pump-induced thermal lensing was also measured,showing good agreement with the performance of the laser.展开更多
The stability of linear planar resonators involved in solid-state lasers is entirely decided by the thermal lens of the laser crystal.There exists a critical point between stable state and unstable state at which the ...The stability of linear planar resonators involved in solid-state lasers is entirely decided by the thermal lens of the laser crystal.There exists a critical point between stable state and unstable state at which the thermal focal length equals the distance from the center of the crystal to one end mirror.Based on this fact,a new method for measuring the thermal focal length of the laser crystal has been presented and applied to a Nd^(3+):YVO_(4) crystal at various absorbed pump power levels up to 10 W.The results have shown to be in good agreement with theoretical calculation.展开更多
The nonlinear-optical coefficients of RCOB(R=Gd,Y)crystals are measured.The spatial distribution of deff effective nonlinear-optical coefficient is determined subsequently.Our experiments show that the maximum deff oc...The nonlinear-optical coefficients of RCOB(R=Gd,Y)crystals are measured.The spatial distribution of deff effective nonlinear-optical coefficient is determined subsequently.Our experiments show that the maximum deff occurs at the second quadrant.The second-harmonic-generation efficiency reaches 48%for a 6 mm-long,(113.2°,47.4°)-cut GdCOB,and 41.5%for a 5mm-long,(113°,36.5°)-cut YCOB,respectively.The intracavity frequency doubling of GdCOB is reported for the first time.展开更多
Large sized and optical quality GdCa_(4)O(BO_(3))_(3)(GdCOB)crystal with calcium partially substituted by strontium(Sr)ions was grown for the first time.The x-ray powder diffraction shows that the Sr ion has an effect...Large sized and optical quality GdCa_(4)O(BO_(3))_(3)(GdCOB)crystal with calcium partially substituted by strontium(Sr)ions was grown for the first time.The x-ray powder diffraction shows that the Sr ion has an effect on the cell parameters of the GdCOB crystal Second-harmonic generation(SHG)experiments were performed on the Sr:GdCOB and GdCOB crystals along the spatial phase-matching direction.The results show that the cw green laser output power is 1.04 W when the laser diode pump power is 10 W in the Nd:YVO_(4)/Sr:GdCOB intracavity laser.Considering the slope efficiency of Nd:YVO_(4) and the fundamental laser in cavity,the intracavity SHG conversion efficiency of the GdCOB crystal is 21%while it is 24%for the Sr:GdCOB crystal,the SHG conversion efficiency is improved by 14%.The effect of the Sr ions on the nonlinearity of the GdCOB crystal is also discussed by using the anion group theory.展开更多
The two-ephoton pumped frequency upconversion optical properties and the two-photon absorption(TPA)induced nonlinear absorption of a new dye trans-4-[p-(N,N-diethylamino)styryl]-N-methylpyridinium iodide(abbreviated a...The two-ephoton pumped frequency upconversion optical properties and the two-photon absorption(TPA)induced nonlinear absorption of a new dye trans-4-[p-(N,N-diethylamino)styryl]-N-methylpyridinium iodide(abbreviated as DEASPI)have been experimentally investigated.This new dye exhibits strong superradiation properties when the pumping power is above the threshold.Furthermore,the superradiation upconversion efficiency and the nonlinear absorption at different wavelengths have been measured.The largest effective molecular TPA cross section was measured to be 3.9 × 10^(-47)cm^(4).s/photon at 930 nm.At 1064 nm,it was 3.85 × 10^(-48)cm^(4).s/photon,much smaller than that at 930 nm.The highest upconversion efficiency is 7.57%at 1020 nm,whereas 4.5%at 1064 nm.展开更多
Two new organic dye samples J and L with a large two-photon absorption(TPA)cross section have been reported.The linear absorption spectra show that there is no linear absorption at the wavelength from 650 to 1200 nm.T...Two new organic dye samples J and L with a large two-photon absorption(TPA)cross section have been reported.The linear absorption spectra show that there is no linear absorption at the wavelength from 650 to 1200 nm.The molecular TPA cross section was measured to be as high as 2.59 × 10^(-47)cm^(4)·s and 2.98 × 10^(-47)cm^(4)·s at 1064 nm for samples J and L,respectively.The input-output curves indicate that there is a clear optical power limiting behaviour when the input intensity is higher than 0.4 GW/cm^(2).Furthermore,basic theorety of TPA process has been discussed.展开更多
Low noise image amplification owing to contradirectional two-wave mixing (CTWM) is proposed and demon strafed in Rh-doped BaTiOa crystal. Comparing with the conventional forward two-wave mixing scheme, an enhancement ...Low noise image amplification owing to contradirectional two-wave mixing (CTWM) is proposed and demon strafed in Rh-doped BaTiOa crystal. Comparing with the conventional forward two-wave mixing scheme, an enhancement of signal-to-noise ratio in the order of 103 is obtained. The theoretical analyses are presented and give a reasonable explanation for the experimental results. The further discussion shows that CTWM scheme can also reduce the influence of the crystal absorption and crystal size on the two-wave mixing process to rise the signal beam gain.展开更多
Second harmonic generation conversion efficiencies of Nd:YCOB and Nd:GdCOB were measured,the effective nonlinear coefficient(de_(ff))for both crystals at different phase-matching angles were estimated by comparison wi...Second harmonic generation conversion efficiencies of Nd:YCOB and Nd:GdCOB were measured,the effective nonlinear coefficient(de_(ff))for both crystals at different phase-matching angles were estimated by comparison with a KTP crystal.The self-frequency doubling laser performance c£these crystals were theoretically calculated by using these rfeff values and slope efficiency of the fundamental wave and lasing threshold.The results coincide very well.展开更多
The thermal lensing effect generated in an end-pumped lightly doped Nd:GdVO4 crystal was found to be considerably weaker than that in Nd:YVO4 having the same Nd3+ concentration. Consequently, the laser performance of ...The thermal lensing effect generated in an end-pumped lightly doped Nd:GdVO4 crystal was found to be considerably weaker than that in Nd:YVO4 having the same Nd3+ concentration. Consequently, the laser performance of Nd:GdVO4 at high pump powers over 20 W was found to be superior to that of Nd:YVO4. TEM00 mode cw radiation of 14.3 W at 1.06μm was achieved with an optical conversion efficiency of 55%, and average slope efficiency of 62%.展开更多
The self-frequency doubling laser performance of Nd:GdCOB crystal cut in phase-matching direction(θ=66.3°,Ф=134.4°)was compared with the crystal cut in the direction of(θ=90°,Ф=46°).Results sho...The self-frequency doubling laser performance of Nd:GdCOB crystal cut in phase-matching direction(θ=66.3°,Ф=134.4°)was compared with the crystal cut in the direction of(θ=90°,Ф=46°).Results show that the former has a higher second-harmonic conversion efficiency than the latter.Using Ti:sapphire laser as pumping source,a maximum of 11.3mW of green light has been obtained with an incident power of 520mW.This corresponds to an optical-optical conversion efficiency of 2.2%.Laser threshold for self-frequency doubling operation is measured to be 1 mW.To our knowledge,this is the lowest threshold achieved so far.展开更多
A mutually pumped phase conjugator with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate is reported,in which both incoherent beams are incident upon the negative c face and th...A mutually pumped phase conjugator with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate is reported,in which both incoherent beams are incident upon the negative c face and they travel in geometric paths similar to the outline of two arches.The maximum reflectivity attains 21%.The tolerance of the output to both incident angles and positions is assessed.No apparent cross talk is observed.A cross-readout mechanism is also used to explain phase-conjugate reflectivity production.It is verified that the configuration can be realized easily for a crystal with two longer a sides.展开更多
Using the Cerenkov second harmonic generation, 478 nm blue and 402nm violet light are generated by direct frequency doubling of 956 and 804 nm diode lasers in a same proton exchanged MgO:LiNbO3 waveguide. Under the lo...Using the Cerenkov second harmonic generation, 478 nm blue and 402nm violet light are generated by direct frequency doubling of 956 and 804 nm diode lasers in a same proton exchanged MgO:LiNbO3 waveguide. Under the low fundamental guide wave power of less than 1mW, the estimated value of the output blue and violet light power is in the order of 0.1-0.01μW.展开更多
A series of Nb doped KTP crystals are grown with seed Aux method and Hux pulling method.The results of our investigation on growth,morphology defects of the crystals are reported in this paper.We obtained the relation...A series of Nb doped KTP crystals are grown with seed Aux method and Hux pulling method.The results of our investigation on growth,morphology defects of the crystals are reported in this paper.We obtained the relationship between Nb contents and second-harmonic generation angles of the crystals.Noncritical phase matching has been realized by 4%Nb doped KTP crystal for Nd:YAG laser 1.06μm output.展开更多
A multistage four-wave mixing interaction region model resulting in self-pumped phase conjugation output of the incident beam is suggested to explain the experimental observations.The competition between forward and b...A multistage four-wave mixing interaction region model resulting in self-pumped phase conjugation output of the incident beam is suggested to explain the experimental observations.The competition between forward and backward two-wave mixing is demonstrated and used to explain the formation of the mechanism.The backscattering beams from random noise beams may be amplified by contradirectional two-wave mixing selectively and act as pumped beams from our experimental observations under a laser entering the negative c face of copper-doped potassium sodium strontium barium niobate crystal.The phase conjugation reflectivity of as high as 33%is measured.展开更多
A mutually pumped phase conjugator is demonstrated with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate,in which the beams travel in a geometric path similar to the outline of...A mutually pumped phase conjugator is demonstrated with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate,in which the beams travel in a geometric path similar to the outline of a sickle.The maximum reflectivity is up to 168%.Faster response times are measured and are also simulated as a function of incident beam power ratio.Four available input geometries are found.The phase conjugation signals exist wide range of angular and positional alignment.No apparent cross talk is observed.The faster build-up process of phase conjugation beams is tentatively explained.展开更多
基金Supported by the National Advanced Materials Commit tee of the"863 Program"under Grant No.863-715-001-0030.
文摘Continuous-wave radiation of 5W at 532 nm was produced with an Nd:YVO_(4)/KTP intracavity&equency-doubled laser end-pumped by a diode-laser-array at pump power of 17.2 W,giving optical conversion efRciency of 29.1%.The output power stability was measured to be better than 1.5%in short term operation.The pump-induced thermal lensing was also measured,showing good agreement with the performance of the laser.
基金Supported by the 863 High Technical Program under Grant No.863-715-001-0030.
文摘The stability of linear planar resonators involved in solid-state lasers is entirely decided by the thermal lens of the laser crystal.There exists a critical point between stable state and unstable state at which the thermal focal length equals the distance from the center of the crystal to one end mirror.Based on this fact,a new method for measuring the thermal focal length of the laser crystal has been presented and applied to a Nd^(3+):YVO_(4) crystal at various absorbed pump power levels up to 10 W.The results have shown to be in good agreement with theoretical calculation.
基金Supported by the Key Program of the National Natural Science Foundation of China under Grant No.69890235the Key Program of Science and Technology Research of the Minis try of Education of China under Grant No.99182.
文摘The nonlinear-optical coefficients of RCOB(R=Gd,Y)crystals are measured.The spatial distribution of deff effective nonlinear-optical coefficient is determined subsequently.Our experiments show that the maximum deff occurs at the second quadrant.The second-harmonic-generation efficiency reaches 48%for a 6 mm-long,(113.2°,47.4°)-cut GdCOB,and 41.5%for a 5mm-long,(113°,36.5°)-cut YCOB,respectively.The intracavity frequency doubling of GdCOB is reported for the first time.
基金Supported by the National Natural Science Foundation of China under Grant No.69890235.
文摘Large sized and optical quality GdCa_(4)O(BO_(3))_(3)(GdCOB)crystal with calcium partially substituted by strontium(Sr)ions was grown for the first time.The x-ray powder diffraction shows that the Sr ion has an effect on the cell parameters of the GdCOB crystal Second-harmonic generation(SHG)experiments were performed on the Sr:GdCOB and GdCOB crystals along the spatial phase-matching direction.The results show that the cw green laser output power is 1.04 W when the laser diode pump power is 10 W in the Nd:YVO_(4)/Sr:GdCOB intracavity laser.Considering the slope efficiency of Nd:YVO_(4) and the fundamental laser in cavity,the intracavity SHG conversion efficiency of the GdCOB crystal is 21%while it is 24%for the Sr:GdCOB crystal,the SHG conversion efficiency is improved by 14%.The effect of the Sr ions on the nonlinearity of the GdCOB crystal is also discussed by using the anion group theory.
基金Supported by the State Kay Program of Ministry of Science and Technology of China under Grant No.G1998061402.
文摘The two-ephoton pumped frequency upconversion optical properties and the two-photon absorption(TPA)induced nonlinear absorption of a new dye trans-4-[p-(N,N-diethylamino)styryl]-N-methylpyridinium iodide(abbreviated as DEASPI)have been experimentally investigated.This new dye exhibits strong superradiation properties when the pumping power is above the threshold.Furthermore,the superradiation upconversion efficiency and the nonlinear absorption at different wavelengths have been measured.The largest effective molecular TPA cross section was measured to be 3.9 × 10^(-47)cm^(4).s/photon at 930 nm.At 1064 nm,it was 3.85 × 10^(-48)cm^(4).s/photon,much smaller than that at 930 nm.The highest upconversion efficiency is 7.57%at 1020 nm,whereas 4.5%at 1064 nm.
基金Supported by a grant of the State Kay Program of China.
文摘Two new organic dye samples J and L with a large two-photon absorption(TPA)cross section have been reported.The linear absorption spectra show that there is no linear absorption at the wavelength from 650 to 1200 nm.The molecular TPA cross section was measured to be as high as 2.59 × 10^(-47)cm^(4)·s and 2.98 × 10^(-47)cm^(4)·s at 1064 nm for samples J and L,respectively.The input-output curves indicate that there is a clear optical power limiting behaviour when the input intensity is higher than 0.4 GW/cm^(2).Furthermore,basic theorety of TPA process has been discussed.
基金Supported by a Grant from Key Research Project No.2 in Climbing Program from the State Science of China.
文摘Low noise image amplification owing to contradirectional two-wave mixing (CTWM) is proposed and demon strafed in Rh-doped BaTiOa crystal. Comparing with the conventional forward two-wave mixing scheme, an enhancement of signal-to-noise ratio in the order of 103 is obtained. The theoretical analyses are presented and give a reasonable explanation for the experimental results. The further discussion shows that CTWM scheme can also reduce the influence of the crystal absorption and crystal size on the two-wave mixing process to rise the signal beam gain.
基金Supported by the National Natural Science Foundation of China under Grant No.68890235.
文摘Second harmonic generation conversion efficiencies of Nd:YCOB and Nd:GdCOB were measured,the effective nonlinear coefficient(de_(ff))for both crystals at different phase-matching angles were estimated by comparison with a KTP crystal.The self-frequency doubling laser performance c£these crystals were theoretically calculated by using these rfeff values and slope efficiency of the fundamental wave and lasing threshold.The results coincide very well.
基金the National 863 High Technical Program under Grant No.863-715-001-0030.
文摘The thermal lensing effect generated in an end-pumped lightly doped Nd:GdVO4 crystal was found to be considerably weaker than that in Nd:YVO4 having the same Nd3+ concentration. Consequently, the laser performance of Nd:GdVO4 at high pump powers over 20 W was found to be superior to that of Nd:YVO4. TEM00 mode cw radiation of 14.3 W at 1.06μm was achieved with an optical conversion efficiency of 55%, and average slope efficiency of 62%.
文摘The self-frequency doubling laser performance of Nd:GdCOB crystal cut in phase-matching direction(θ=66.3°,Ф=134.4°)was compared with the crystal cut in the direction of(θ=90°,Ф=46°).Results show that the former has a higher second-harmonic conversion efficiency than the latter.Using Ti:sapphire laser as pumping source,a maximum of 11.3mW of green light has been obtained with an incident power of 520mW.This corresponds to an optical-optical conversion efficiency of 2.2%.Laser threshold for self-frequency doubling operation is measured to be 1 mW.To our knowledge,this is the lowest threshold achieved so far.
基金Supported by the Grant for a Key Research Project in Climbing Program from the State Science and Technology Commission of China.
文摘A mutually pumped phase conjugator with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate is reported,in which both incoherent beams are incident upon the negative c face and they travel in geometric paths similar to the outline of two arches.The maximum reflectivity attains 21%.The tolerance of the output to both incident angles and positions is assessed.No apparent cross talk is observed.A cross-readout mechanism is also used to explain phase-conjugate reflectivity production.It is verified that the configuration can be realized easily for a crystal with two longer a sides.
文摘Using the Cerenkov second harmonic generation, 478 nm blue and 402nm violet light are generated by direct frequency doubling of 956 and 804 nm diode lasers in a same proton exchanged MgO:LiNbO3 waveguide. Under the low fundamental guide wave power of less than 1mW, the estimated value of the output blue and violet light power is in the order of 0.1-0.01μW.
基金Supported by a grant for Research Project in Climbing Program from the Science and Technology Commission of China.
文摘A series of Nb doped KTP crystals are grown with seed Aux method and Hux pulling method.The results of our investigation on growth,morphology defects of the crystals are reported in this paper.We obtained the relationship between Nb contents and second-harmonic generation angles of the crystals.Noncritical phase matching has been realized by 4%Nb doped KTP crystal for Nd:YAG laser 1.06μm output.
基金Supported by a Grant for a Key Research Project in Climbing Program from the State Science and Technology Commission of China.
文摘A multistage four-wave mixing interaction region model resulting in self-pumped phase conjugation output of the incident beam is suggested to explain the experimental observations.The competition between forward and backward two-wave mixing is demonstrated and used to explain the formation of the mechanism.The backscattering beams from random noise beams may be amplified by contradirectional two-wave mixing selectively and act as pumped beams from our experimental observations under a laser entering the negative c face of copper-doped potassium sodium strontium barium niobate crystal.The phase conjugation reflectivity of as high as 33%is measured.
基金Supported by a grant for a Key Research Project in Climbing Program from the State Science and Technology Commission of China。
文摘A mutually pumped phase conjugator is demonstrated with a novel photorefractive crystal of copper-doped potassium sodium strontium barium niobate,in which the beams travel in a geometric path similar to the outline of a sickle.The maximum reflectivity is up to 168%.Faster response times are measured and are also simulated as a function of incident beam power ratio.Four available input geometries are found.The phase conjugation signals exist wide range of angular and positional alignment.No apparent cross talk is observed.The faster build-up process of phase conjugation beams is tentatively explained.
