We demonstrated a robust power-scalable Kerr-lens mode-locked（KLM） operation based on a Yb：YAG thin-disk oscillator.15-W,272-fs pulses were realized at a repetition rate of 86.7 MHz with an additional Kerr medium a...We demonstrated a robust power-scalable Kerr-lens mode-locked（KLM） operation based on a Yb：YAG thin-disk oscillator.15-W,272-fs pulses were realized at a repetition rate of 86.7 MHz with an additional Kerr medium and a 2.5 mm hard aperture in the cavity.247-fs pulses with an average power of 11 W could also be obtained by using a 2.4 mm hard aperture.Based on this shorter pulse,high efficient second-harmonic generation（SHG） was performed with a 1.7-mm-long Li B3O5（LBO） crystal.The SHG laser power was up to 5 W with the power fluctuation RMS of 1% measured over one hour.展开更多
Pumped by a 940 nm fiber-coupled diode laser, a passively mode-locked Yb：YAG thin disk oscillator was demonstrated with a semiconductor saturable absorber mirror（SESAM）. 12.1 W mode-locked pulses were obtained with...Pumped by a 940 nm fiber-coupled diode laser, a passively mode-locked Yb：YAG thin disk oscillator was demonstrated with a semiconductor saturable absorber mirror（SESAM）. 12.1 W mode-locked pulses were obtained with pulse duration of 698 fs at the repetition rate of 57.43 MHz. Measurement showed that the beam quality was close to the diffraction limit.展开更多
The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function of the semiconductor disk laser, and analyses the heat effect by the experimentally measured photolu...The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function of the semiconductor disk laser, and analyses the heat effect by the experimentally measured photoluminescence spectrum of the laser chip at different pump power and different temperatures. We can see that: with increasing pump power, the thermal effect of the gain material becomes seriously and causes the saturation of carrier lifetime, so the electron-hole pair created in the absorbtion layer has no enough time to rate to one of the wells, and the non-radiative recombination happens in the barrier. When the thermal effect becomes stronger, the chip will be not lasing. This phenomenon is from the smaller energy offset between barrier and quantum well. We optimize the original structure design and experimental technology. A non-absorbing AlGaAs layer which is transparent to the pumping and laser wavelength is added to confine the carriers in the quantum wells. At the same time a DBR with double reflecting band is induced to improve the absorbing efficiency of the pumping light. The single QW is replaced by the three narrow QWs. This three QWs structure can add the quantum state of QW, increase the recombination probability of carriers in the QWs and reduce the heat effect. The chemical etching equipment is also improved to control the surface unevenness to be within 50 nm.展开更多
Dual-comb spectroscopy provides a marked advantage over single-comb techniques for molecular fingerprinting,particularly in terms of scanning speed.The single-cavity dual-comb system is a simpler approach to dual-comb...Dual-comb spectroscopy provides a marked advantage over single-comb techniques for molecular fingerprinting,particularly in terms of scanning speed.The single-cavity dual-comb system is a simpler approach to dual-comb operation.This system utilized a single free-running oscillator to generate both combs,eliminating the complex setups with multiple lasers.Here,we report a high-power deep ultraviolet(DUV)dual comb driven by a thin-disk single-cavity(TDSC)Yb:YAG dual-comb laser.A TDSC Yb:YAG oscillator generates 2 comb beams with repetition rates near 76 MHz,differing by a few kilohertz and tunable by adjusting one cavity arm.Both combs operate at a central wavelength of 1,030 nm with pulse durations of 431 and 411 fs,respectively,and achieve average output powers of 5 W each.We employed the TDSC as a light source for a ranging system,demonstrating a measurement difference accuracy of 1.23μm for a target at 6.5 m with an average acquisition time of 330 ms.To extend the dual comb to DUV region,we generated the second and fourth harmonics using LBO and BBO crystals,respectively,with conversion efficiencies exceeding 40%and 10%for both comb beams.With over 300 mW of power at 258 nm for each comb,we successfully demonstrated DUV dual-comb operation with a frequency difference of 20 kHz.This represents the first DUV dual comb generated by a TDSC laser.Finally,we discussed the prospect of extending the dual-comb range to extreme UV and terahertz dual combs based on the TDSC Yb:YAG laser platform.展开更多
Recent high-resolution observations have established a strong link between black hole jets and accretion disk structures,particularly in the 3.5 mm wavelength band[Nature.616,686(2023)].In this work,we propose a"...Recent high-resolution observations have established a strong link between black hole jets and accretion disk structures,particularly in the 3.5 mm wavelength band[Nature.616,686(2023)].In this work,we propose a"jet-modified Novikov-Thorne disk model"that explicitly incorporates jet luminosity into the accretion disk radiation framework.By integrating synchrotron radiation from relativistic electrons in the jet,we derive a modified luminosity function that accounts for both the accretion disk and jet contributions.Our analysis demonstrates that the inclusion of j et luminosity enhances the total accretion disk luminosity by approximately 33.5%,as derived from the integration of radiative flux.Furthermore,we compare our modified model with the standard Novikov-Thorne model and find that the jet contribution remains significant across different observational inclinations.These results highlight the necessity of incorporating jet effects when estimating the observable flux of black hole accretion systems,which has direct implications for future astronomical observations.展开更多
In this paper, we propose and demonstrate an adjustable-free and movable Nd:YVO_(4)thin disk laser based on the telecentric cat’s eye cavity. We design a V-shaped laser cavity containing two reflectors with Nd:YVO_(4...In this paper, we propose and demonstrate an adjustable-free and movable Nd:YVO_(4)thin disk laser based on the telecentric cat’s eye cavity. We design a V-shaped laser cavity containing two reflectors with Nd:YVO_(4)thin disks as the gain medium.The experimental results from the traditional plane-plane cavity, plane-telecentric cat’s eye cavity, and double telecentric cat’s eye cavity are compared. They show that plane-telecentric cat’s eye cavity laser can keep operating at the adjustablefree range of -6° to +6°, which is up to 60 times better than that of traditional plane-plane cavity. In the double telecentric cat’s eye case, the adjustable-free range is improved to-13° to +13°. Additionally, in the case of the double telecentric cat’s eye cavity, the output telecentric cat’s eye can achieve free movement within the horizontal range of ±20 mm.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
In this paper,we study the shadows and observational appearance of the Ayón-Beato-García(ABG)black hole,which is surrounded by a thin disk accretion.For a four-dimensional ABG black hole,as the charge q incr...In this paper,we study the shadows and observational appearance of the Ayón-Beato-García(ABG)black hole,which is surrounded by a thin disk accretion.For a four-dimensional ABG black hole,as the charge q increases,the event horizon r+,radius rp and impact parameter bp of the photon sphere decrease,while the maximum value of effective potential Veff increases.However,as the termγassociated with nonlinear electrodynamics increases,the related physical quantities r+,rp and bp increase,but the maximum value of Veff decreases.When the light ray reaches the vicinity of the ABG black hole,one can observe the trajectories of the light rays appearing as three types,i.e.,direct emission,lens ring and photon ring.Furthermore,the shadows and the observational appearance of the ABG black hole are studied.The results show that the charge q and the termγhave a great influence on the shape and intensity of the black hole shadow.When the relevant state parameters change or the emission model changes,it can be argued that it is the direct emission that plays a decisive role in the total observed intensity of the ABG black hole,while the contribution of the lens ring to the total observed intensity is small and the photon ring makes almost no contribution.展开更多
Optical vortices carrying orbital angular momentum and spiral wavefront phases have garnered increasing research interest owing to their numerous applications.Here,we present a simple yet effective approach to generat...Optical vortices carrying orbital angular momentum and spiral wavefront phases have garnered increasing research interest owing to their numerous applications.Here,we present a simple yet effective approach to generate powerful optical vortices directly from a thin-disk laser oscillator.The demonstrated source delivered Laguerre-Gaussian beams with an output power of up to 101 W.To the best of our knowledge,this is the highest output power of all optical vortex laser oscillators.The high-power vortex output will have significant implications for laser ablation and micromachining at high throughput and for large-area applications.Additionally,it serves as a new platform for the further development of more complex high-power optical-vortex beams.展开更多
The characteristics and images of Einstein-Maxwell-dilaton(EMD)black holes are examined in this paper,focusing on their effective potential,photon trajectories,and images with both thin and thick accretion disks.We fi...The characteristics and images of Einstein-Maxwell-dilaton(EMD)black holes are examined in this paper,focusing on their effective potential,photon trajectories,and images with both thin and thick accretion disks.We find that the shadow and photon sphere radii decrease as the dilaton charge increases.As the observation inclination increases,the direct and secondary images become distinct,with the direct image appearing hat-shaped.Simulations indicate that the brightness of the shadow and photon ring is higher in static spherical accretion flows compared to infalling ones.The study also shows that in thin disk accretion flows,direct emission predominantly influences the observed luminosity,while photon ring emission is less significant.Additionally,the appearance of black hole images varies with the observer’s inclination angle.展开更多
The image of a black hole(BH)consists of direct and secondary images that depend on the observer position.We investigate the optical appearance of a Schwarzschild BH in the context of a string cloud to reveal how the...The image of a black hole(BH)consists of direct and secondary images that depend on the observer position.We investigate the optical appearance of a Schwarzschild BH in the context of a string cloud to reveal how the BH’s observable characteristics are influenced by the inclination angle,string cloud parameter,and impact parameter.Following Luminet’s work[Astron.Astrophys.75,228(1979)],we adopt a semi-analytic method to calculate the total bending angle of the light ray and derive the direct and secondary images of the Schwarzschild string cloud BH.Our results show that an increase in the inclination angle leads to a more pronounced separation of the images.We consider the gravitational redshift and present the redshift distribution of the direct image while illustrating the flux distribution.We observe that the direct image exhibits blueshift and redshift simultaneously,and the asymmetry of the flux distribution increases with the inclination angle.Finally,we obtain the Schwarzschild string cloud BH image via a numerical simulation,which provides an approximate illustration of the EHT resolution.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2013CB922402)the National Major Instrument Program of China(Grant No.2012YQ120047)the National Natural Science Foundation of China(Grant Nos.11434016 and 61210017)
文摘We demonstrated a robust power-scalable Kerr-lens mode-locked（KLM） operation based on a Yb：YAG thin-disk oscillator.15-W,272-fs pulses were realized at a repetition rate of 86.7 MHz with an additional Kerr medium and a 2.5 mm hard aperture in the cavity.247-fs pulses with an average power of 11 W could also be obtained by using a 2.4 mm hard aperture.Based on this shorter pulse,high efficient second-harmonic generation（SHG） was performed with a 1.7-mm-long Li B3O5（LBO） crystal.The SHG laser power was up to 5 W with the power fluctuation RMS of 1% measured over one hour.
基金Project supported by the National Key Basic Research Program of China(Grant No.2013CB922402)the National Major Instrument Program of China(Grant No.2012YQ120047)the National Natural Science Foundation of China(Grant No.61210017)
文摘Pumped by a 940 nm fiber-coupled diode laser, a passively mode-locked Yb：YAG thin disk oscillator was demonstrated with a semiconductor saturable absorber mirror（SESAM）. 12.1 W mode-locked pulses were obtained with pulse duration of 698 fs at the repetition rate of 57.43 MHz. Measurement showed that the beam quality was close to the diffraction limit.
文摘The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function of the semiconductor disk laser, and analyses the heat effect by the experimentally measured photoluminescence spectrum of the laser chip at different pump power and different temperatures. We can see that: with increasing pump power, the thermal effect of the gain material becomes seriously and causes the saturation of carrier lifetime, so the electron-hole pair created in the absorbtion layer has no enough time to rate to one of the wells, and the non-radiative recombination happens in the barrier. When the thermal effect becomes stronger, the chip will be not lasing. This phenomenon is from the smaller energy offset between barrier and quantum well. We optimize the original structure design and experimental technology. A non-absorbing AlGaAs layer which is transparent to the pumping and laser wavelength is added to confine the carriers in the quantum wells. At the same time a DBR with double reflecting band is induced to improve the absorbing efficiency of the pumping light. The single QW is replaced by the three narrow QWs. This three QWs structure can add the quantum state of QW, increase the recombination probability of carriers in the QWs and reduce the heat effect. The chemical etching equipment is also improved to control the surface unevenness to be within 50 nm.
基金supported by the Project of Aerosapce Information Research Institute,Chinese Academy of Sciences(E1Z1D101 and E2Z2D101)the Project of Chinese Academy of Sciences(E33310030D)the National Natural Science Foundation of China(62335009).
文摘Dual-comb spectroscopy provides a marked advantage over single-comb techniques for molecular fingerprinting,particularly in terms of scanning speed.The single-cavity dual-comb system is a simpler approach to dual-comb operation.This system utilized a single free-running oscillator to generate both combs,eliminating the complex setups with multiple lasers.Here,we report a high-power deep ultraviolet(DUV)dual comb driven by a thin-disk single-cavity(TDSC)Yb:YAG dual-comb laser.A TDSC Yb:YAG oscillator generates 2 comb beams with repetition rates near 76 MHz,differing by a few kilohertz and tunable by adjusting one cavity arm.Both combs operate at a central wavelength of 1,030 nm with pulse durations of 431 and 411 fs,respectively,and achieve average output powers of 5 W each.We employed the TDSC as a light source for a ranging system,demonstrating a measurement difference accuracy of 1.23μm for a target at 6.5 m with an average acquisition time of 330 ms.To extend the dual comb to DUV region,we generated the second and fourth harmonics using LBO and BBO crystals,respectively,with conversion efficiencies exceeding 40%and 10%for both comb beams.With over 300 mW of power at 258 nm for each comb,we successfully demonstrated DUV dual-comb operation with a frequency difference of 20 kHz.This represents the first DUV dual comb generated by a TDSC laser.Finally,we discussed the prospect of extending the dual-comb range to extreme UV and terahertz dual combs based on the TDSC Yb:YAG laser platform.
基金Supported by the Fund Project of Chongqing Normal University(24XLB033)。
文摘Recent high-resolution observations have established a strong link between black hole jets and accretion disk structures,particularly in the 3.5 mm wavelength band[Nature.616,686(2023)].In this work,we propose a"jet-modified Novikov-Thorne disk model"that explicitly incorporates jet luminosity into the accretion disk radiation framework.By integrating synchrotron radiation from relativistic electrons in the jet,we derive a modified luminosity function that accounts for both the accretion disk and jet contributions.Our analysis demonstrates that the inclusion of j et luminosity enhances the total accretion disk luminosity by approximately 33.5%,as derived from the integration of radiative flux.Furthermore,we compare our modified model with the standard Novikov-Thorne model and find that the jet contribution remains significant across different observational inclinations.These results highlight the necessity of incorporating jet effects when estimating the observable flux of black hole accretion systems,which has direct implications for future astronomical observations.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(Nos.61775223 and 11974367)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB1603)Shanghai Science and Technology Innovation Action Plan Project(No.19142202500)。
文摘In this paper, we propose and demonstrate an adjustable-free and movable Nd:YVO_(4)thin disk laser based on the telecentric cat’s eye cavity. We design a V-shaped laser cavity containing two reflectors with Nd:YVO_(4)thin disks as the gain medium.The experimental results from the traditional plane-plane cavity, plane-telecentric cat’s eye cavity, and double telecentric cat’s eye cavity are compared. They show that plane-telecentric cat’s eye cavity laser can keep operating at the adjustablefree range of -6° to +6°, which is up to 60 times better than that of traditional plane-plane cavity. In the double telecentric cat’s eye case, the adjustable-free range is improved to-13° to +13°. Additionally, in the case of the double telecentric cat’s eye cavity, the output telecentric cat’s eye can achieve free movement within the horizontal range of ±20 mm.
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the National Natural Science Foundation of China(Grant Nos.11875095 and 11903025)the starting fund of China West Normal University(Grant No.18Q062)+2 种基金the Sichuan Youth Science and Technology Innovation Research Team(21CXTD0038)the Chongqing Science and Technology Bureau(cstc2022ycjh-bgzxm0161)the Natural Science Foundation of SiChuan Province(2022NSFSC1833).
文摘In this paper,we study the shadows and observational appearance of the Ayón-Beato-García(ABG)black hole,which is surrounded by a thin disk accretion.For a four-dimensional ABG black hole,as the charge q increases,the event horizon r+,radius rp and impact parameter bp of the photon sphere decrease,while the maximum value of effective potential Veff increases.However,as the termγassociated with nonlinear electrodynamics increases,the related physical quantities r+,rp and bp increase,but the maximum value of Veff decreases.When the light ray reaches the vicinity of the ABG black hole,one can observe the trajectories of the light rays appearing as three types,i.e.,direct emission,lens ring and photon ring.Furthermore,the shadows and the observational appearance of the ABG black hole are studied.The results show that the charge q and the termγhave a great influence on the shape and intensity of the black hole shadow.When the relevant state parameters change or the emission model changes,it can be argued that it is the direct emission that plays a decisive role in the total observed intensity of the ABG black hole,while the contribution of the lens ring to the total observed intensity is small and the photon ring makes almost no contribution.
基金supported by the National Natural Science Foundation of China(Nos.62075068 and 62335009)the National Key Research and Development Program of China(2022YFC2203902 and 2022YFC2203904)+1 种基金the International Science and Technology Cooperation Program of Hubei Province(No.2021EHB004)the Natural Science Foundation of Hubei Province(2022CFB099).
文摘Optical vortices carrying orbital angular momentum and spiral wavefront phases have garnered increasing research interest owing to their numerous applications.Here,we present a simple yet effective approach to generate powerful optical vortices directly from a thin-disk laser oscillator.The demonstrated source delivered Laguerre-Gaussian beams with an output power of up to 101 W.To the best of our knowledge,this is the highest output power of all optical vortex laser oscillators.The high-power vortex output will have significant implications for laser ablation and micromachining at high throughput and for large-area applications.Additionally,it serves as a new platform for the further development of more complex high-power optical-vortex beams.
基金supported by the National Natural Science Foundation of China(Grant Nos.11675140,11705005,and 12375043)the Innovation and Development Joint Foundation of Chongqing Natural Science Foundation(Grant No.CSTB2022NSCQ-LZX0021)+1 种基金the Basic Research Project of Science and Technology Committee of Chongqing(Grant No.CSTB2023NSCQ-MSX0324)the Fund Project of Chongqing Normal University(Grant No.24XLB033).
文摘The characteristics and images of Einstein-Maxwell-dilaton(EMD)black holes are examined in this paper,focusing on their effective potential,photon trajectories,and images with both thin and thick accretion disks.We find that the shadow and photon sphere radii decrease as the dilaton charge increases.As the observation inclination increases,the direct and secondary images become distinct,with the direct image appearing hat-shaped.Simulations indicate that the brightness of the shadow and photon ring is higher in static spherical accretion flows compared to infalling ones.The study also shows that in thin disk accretion flows,direct emission predominantly influences the observed luminosity,while photon ring emission is less significant.Additionally,the appearance of black hole images varies with the observer’s inclination angle.
基金Supported by the National Natural Science Foundation of China(11903025)the Natural Science Foundation of Sichuan Province,China(2022NSFSC1833)。
文摘The image of a black hole(BH)consists of direct and secondary images that depend on the observer position.We investigate the optical appearance of a Schwarzschild BH in the context of a string cloud to reveal how the BH’s observable characteristics are influenced by the inclination angle,string cloud parameter,and impact parameter.Following Luminet’s work[Astron.Astrophys.75,228(1979)],we adopt a semi-analytic method to calculate the total bending angle of the light ray and derive the direct and secondary images of the Schwarzschild string cloud BH.Our results show that an increase in the inclination angle leads to a more pronounced separation of the images.We consider the gravitational redshift and present the redshift distribution of the direct image while illustrating the flux distribution.We observe that the direct image exhibits blueshift and redshift simultaneously,and the asymmetry of the flux distribution increases with the inclination angle.Finally,we obtain the Schwarzschild string cloud BH image via a numerical simulation,which provides an approximate illustration of the EHT resolution.
