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
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
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
This paper has derived the general formulae of observed line profiles based on the effects of radial velocity on the standard thin disk fluid around a rotating black hole. Through the ray-tracing method the line profi...This paper has derived the general formulae of observed line profiles based on the effects of radial velocity on the standard thin disk fluid around a rotating black hole. Through the ray-tracing method the line profiles of different parameters have been calculated. Comparison of the line profiles with and without a radial velocity shows that the effects of radial velocity on line profiles cannot be neglected in most cases. In both cases the accretive disk imaging shape remains unchanged.展开更多
We theoretically study the nonlinear compression of a 20-rnJ, 1030-nm picosecond chirped pulse from the thin-disk amplifier in a krypton gas-filled hollow-core fiber. The chirp from the thin-disk amplifier system has ...We theoretically study the nonlinear compression of a 20-rnJ, 1030-nm picosecond chirped pulse from the thin-disk amplifier in a krypton gas-filled hollow-core fiber. The chirp from the thin-disk amplifier system has little influence on the initial pulse, however, it shows an effect on the nonlinear compression in hollow-core fiber. We use a large diameter hollow waveguide to restrict undesirable nonlinear effects such as ionization; on the other hand, we employ suitable gas pressure and fiber length to promise enough spectral broadening; with 600-μm, 6-bar (1 bar = 105 Pa), 1.8-m hollow fiber, we obtain 31.5-fs pulse. Moreover, we calculate and discuss the optimal fiber lengths and gas pressures with different initial durations induced by different grating compression angles for reaching a given bandwidth. These results are meaningful for a compression scheme from picoseconds to femtoseconds.展开更多
This paper reports that amorphous silicon nitride （a-SiNx） overcoats were deposited at room temperature by microwave ECR plasma enhanced unbalanced magnetron sputtering. The 2 nm a-SiNs overcoat has better anti-corr...This paper reports that amorphous silicon nitride （a-SiNx） overcoats were deposited at room temperature by microwave ECR plasma enhanced unbalanced magnetron sputtering. The 2 nm a-SiNs overcoat has better anti-corrosion properties than that of reference a-CNx overcoats （2 4.5 nm）. The superior anti-corrosion performance is attributed to its stoichiometric bond structure, where 94.8% Si atoms form Si-N asymmetric stretching vibration bonds. The N/Si ratio is 1.33 as in the stoichiometry of Si3N4 and corresponds to the highest hardness of 25.0 GPa. The surface is atomically smooth with RMS 〈 0.2 nm. The ultra-thin a-SiNx overcoats are promising for hard disks and read/write heads protective coatings.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
This paper introduces some final results of some key technologies in magnetic disk drives. We dicuss the design and experiment of thin film head, magnetic fluid exclusion seal system, head disk interface and the engin...This paper introduces some final results of some key technologies in magnetic disk drives. We dicuss the design and experiment of thin film head, magnetic fluid exclusion seal system, head disk interface and the engineering appilcations of these technologies in magnetic disk drives.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
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.
文摘This paper has derived the general formulae of observed line profiles based on the effects of radial velocity on the standard thin disk fluid around a rotating black hole. Through the ray-tracing method the line profiles of different parameters have been calculated. Comparison of the line profiles with and without a radial velocity shows that the effects of radial velocity on line profiles cannot be neglected in most cases. In both cases the accretive disk imaging shape remains unchanged.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB808101)the Funds from the Chinese Academy of Sciences,and the National Natural Science Foundation of China(Grant Nos.11127901,10734080,61221064,60908008,and 61078037)
文摘We theoretically study the nonlinear compression of a 20-rnJ, 1030-nm picosecond chirped pulse from the thin-disk amplifier in a krypton gas-filled hollow-core fiber. The chirp from the thin-disk amplifier system has little influence on the initial pulse, however, it shows an effect on the nonlinear compression in hollow-core fiber. We use a large diameter hollow waveguide to restrict undesirable nonlinear effects such as ionization; on the other hand, we employ suitable gas pressure and fiber length to promise enough spectral broadening; with 600-μm, 6-bar (1 bar = 105 Pa), 1.8-m hollow fiber, we obtain 31.5-fs pulse. Moreover, we calculate and discuss the optimal fiber lengths and gas pressures with different initial durations induced by different grating compression angles for reaching a given bandwidth. These results are meaningful for a compression scheme from picoseconds to femtoseconds.
基金Project supported by the Major Program of the National Natural Science Foundation of China (Grant No 50390060)the National Natural Science Foundation of China (Grant Nos 60576022 and 50572012)
文摘This paper reports that amorphous silicon nitride （a-SiNx） overcoats were deposited at room temperature by microwave ECR plasma enhanced unbalanced magnetron sputtering. The 2 nm a-SiNs overcoat has better anti-corrosion properties than that of reference a-CNx overcoats （2 4.5 nm）. The superior anti-corrosion performance is attributed to its stoichiometric bond structure, where 94.8% Si atoms form Si-N asymmetric stretching vibration bonds. The N/Si ratio is 1.33 as in the stoichiometry of Si3N4 and corresponds to the highest hardness of 25.0 GPa. The surface is atomically smooth with RMS 〈 0.2 nm. The ultra-thin a-SiNx overcoats are promising for hard disks and read/write heads protective coatings.
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.
文摘This paper introduces some final results of some key technologies in magnetic disk drives. We dicuss the design and experiment of thin film head, magnetic fluid exclusion seal system, head disk interface and the engineering appilcations of these technologies in magnetic disk drives.
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.
