The modulation transfer spectroscopy in an ytterbium hollow cathode lamp at 399 nm is measured. The error signal for frequency locking is optimized by measuring the dependences of its slope, linewidth and magnitude on...The modulation transfer spectroscopy in an ytterbium hollow cathode lamp at 399 nm is measured. The error signal for frequency locking is optimized by measuring the dependences of its slope, linewidth and magnitude on various parameters. Under the optimum condition, the laser frequency at 399 nm can be stabilized. The long-term stability of laser frequency is measured by monitoring the fluorescence signal of the ytterbium atomic beam induced by the locked laser. The laser frequency is shown to be tightly locked, and the stabilized laser is successfully applied to the cooling of ytterbium atoms.展开更多
We report a robust method of directly stabilizing a grating feedback diode laser to an arbitrary frequency in a large range. The error signal, induced from the difference between the frequency measured by a wavelength...We report a robust method of directly stabilizing a grating feedback diode laser to an arbitrary frequency in a large range. The error signal, induced from the difference between the frequency measured by a wavelength meter and the preset target frequency, is fed back to the piezoelectric transducer module of the diode laser via a sound card in the computer. A visual Labview procedure is developed to realize a feedback system. In our experiment the frequency drift of the diode laser is reduced to 8 MHz within 25 min. The robust scheme can be adapted to realize the arbitrary frequency stabilization for many other kinds of lasers.展开更多
We develop a high-performance ultraviolet(UV)frequency stabilization technique implemented directly on UV diode lasers by combining the dichroic atomic vapor laser lock and the resonant transfer cavity lock.As an exam...We develop a high-performance ultraviolet(UV)frequency stabilization technique implemented directly on UV diode lasers by combining the dichroic atomic vapor laser lock and the resonant transfer cavity lock.As an example,we demonstrate a stable locking with measured frequency standard deviations of approximately 200 kHz and 300 kHz for 399 nm and 370 nm diode lasers in 20 min.We achieve a long-term frequency drift of no more than 1 MHz for the target 370 nm laser within an hour,which is further verified with fluorescence count rates of a single trapped ^171Yb+ion.We also find strong linear correlations between lock points and environmental factors such as temperature and atmospheric pressure.Our approach provides a simple and stable solution at a relatively low cost,and features flexible control,high feedback bandwidth and minimal power consumption of the target UV laser.展开更多
A method is presented to improve the laser frequency stabilization for the optical pumping cesium clock. By comparing the laser frequency stabilization of different schemes, we verify that the light angle is an import...A method is presented to improve the laser frequency stabilization for the optical pumping cesium clock. By comparing the laser frequency stabilization of different schemes, we verify that the light angle is an important factor that limits the long-term frequency stability. We minimize the drift of the light angle by using a fiber- coupled output, and lock the frequency of a distributed-feedback diode laser to the fluorescence spectrum of the atomic beam. The measured frequency stability is about 3.5 ×10^-11 at i s and reaches 1.5 × 10^-12 at 2000s. The Allan variance keeps going down for up to thousands of seconds, indicating that the medium- and long-term stability of the laser frequency is significantly improved and perfectly fulfills the requirement for the optical pumping cesium clock.展开更多
We report laser frequency stabilization with modulation transfer spectroscopy（MTS） on 85 Rb atoms. With both PZT（piezo-electric transducer） slow-loop feedback and current fastloop feedback to the laser head, we ge...We report laser frequency stabilization with modulation transfer spectroscopy（MTS） on 85 Rb atoms. With both PZT（piezo-electric transducer） slow-loop feedback and current fastloop feedback to the laser head, we get a linewidth narrowing less than 5 kHz simultaneously. Laser injection to a laser diode and frequency beating with another polarization spectroscopy based stabilization setup are also employed to check the narrow linewidth property. With the help of the technique, a linewidth around k Hz-level laser is obtained and pave the way for the locking of the lattice laser of ytterbium clock with transfer cavity technique. The setup can be used as a frequency reference for precise frequency control of atomic clock system.展开更多
Atomic spectroscopy serves as the basis for quantum precision measurements,where frequency-stabilized lasers are crucial for obtaining accurate atomic spectra.This work introduces a compact laser frequency stabilizati...Atomic spectroscopy serves as the basis for quantum precision measurements,where frequency-stabilized lasers are crucial for obtaining accurate atomic spectra.This work introduces a compact laser frequency stabilization system that employs a multifunctional metasurface to adjust the polarization,amplitude,and propagation direction of incident light.By combining with a Rb atomic vapor cell,the system achieves a tunable sub-Doppler spectrum for laser frequency stabilization.The experimental result demonstrates that a laser frequency stability of 3×10−11 is attained from 1 to 200 s at 780 nm with the input power at 20µW.The devices hold significant potential for compactness,integration,and mass production,making them highly suitable for quantum measurement applications.展开更多
A simple and robust multiple wavelength frequency stabilization system is demonstrated using a single transfer cavity and a1062-nm ultra-stable laser for all the lasers used in a mercury optical lattice clock.Offset s...A simple and robust multiple wavelength frequency stabilization system is demonstrated using a single transfer cavity and a1062-nm ultra-stable laser for all the lasers used in a mercury optical lattice clock.Offset sideband locking is employed to tune the laser frequency while dichroic mirrors and differentiated modulation frequencies are utilized for the Pound–Drever–Hall locking of four-color lasers.For the most demanding lasers at 1015 nm and 725 nm,the line width of the beat note is reduced to 27 kHz and 17 kHz,respectively.The frequency fluctuation for the transfer-locked 1015-nm laser is less than 10 kHz,which is much better than the lasers locked to an atomic spectrum.Using its high stability of 5×10^(-12)over100 s,the transfer-locked 1015-nm laser is employed for low-noise frequency modulated saturated absorption spectroscopy.This approach could also be used in various situations for the research of optical clocks,Rydberg atoms,laser cooling of molecules,and quantum computation with neutral atoms.展开更多
In this study,a miniature laser frequency stabilization module for cold atom sensing applications was designed and realized.The module can lock the laser frequency to the saturated absorption spectrum of the D2 line o...In this study,a miniature laser frequency stabilization module for cold atom sensing applications was designed and realized.The module can lock the laser frequency to the saturated absorption spectrum of the D2 line of rubidium(Rb)atoms using the frequency modulation spectroscopy method.The module core is a tiny Rb cell,co-packaged with the saturation absorption optical setup,temperature control circuit,and detection circuit through a joint optical-mechanical-electrical design for a total volume of only 40 mm×15 mm×30 mm.The frequency fluctuation of the 780 nm laser after frequency stabilization by the module was within 1 MHz over 1000 s,which is adequate for magneto-optical trap experiments.The results verify the feasibility of the module as a frequency reference and provide a light source for portable cold atom sensing devices.展开更多
The frequency stability of free-running semiconductor lasers is influenced by several factors, such as driving current and external operating environment. The frequency stabilization of laser has become an internation...The frequency stability of free-running semiconductor lasers is influenced by several factors, such as driving current and external operating environment. The frequency stabilization of laser has become an international research hotspot in recent years. This paper reviews active frequency stabilization technologies of laser diodes and elaborates their principles. Based on differences of frequency discrimination curves, these active frequency stabilization technologies are classified into three major types, which are harmonic frequency stabilization,Pound-Drever-Hall(PDH) technology and curve subtraction frequency stabilization. Further, merits and demerits of each technology are compared from aspects of frequency stability and structure complexity. Finally, prospects of frequency stabilization technologies of semiconductor lasers are discussed in detail. Combining several of these methods are future trends, especially the combination of frequency stabilization of F–P cavity. And PID electronic control for optimizing the servo system is generally added in the methods mentioned above.展开更多
Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation...Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation failures in line commutated converter high voltage direct current(LCC-HVDC)systems at the receiving end leads to short-term power shortage(STPS),which differs from traditional frequency stability issues.STPS occurs during the generator’s power angle swing phase,before the governor responds,and is on a timescale that is not related to primary frequency regulation.This paper addresses these challenges by examining the impact of LVRT on voltage stability,developing a frequency response model to analyze the mechanism of frequency instability caused by STPS,deriving the impact of STPS on the maximum frequency deviation,and introducing an energy deficiency factor to assess its impact on regional frequency stability.The East China Power Grid is used as a case study,where the energy deficiency factor is calculated to validate the proposed mechanism.STPS is mainly compensated by the rotor kinetic energy of the generators in this region,with minimal impact on other regions.It is concluded that the energy deficiency factor provides an effective explanation for the spatial distribution of the impact of STPS on system frequency.展开更多
The frequency regulation reserve setting of wind-PV-storage power stations is crucial.However,the existing grid codes set up the station reserve in a static manner,where the synchronous generator characteristics and f...The frequency regulation reserve setting of wind-PV-storage power stations is crucial.However,the existing grid codes set up the station reserve in a static manner,where the synchronous generator characteristics and frequency-step disturbance scenario are considered.Thus,the advantages of flexible regulation of renewable generations are wasted,resulting in excessive curtailment of wind and solar resources.In this study,a method for optimizing the frequency regulation reserve of wind PV storage power stations was developed.Moreover,a station frequency regulation model was constructed,considering the field dynamic response and the coupling between the station and system frequency dynamics.Furthermore,a method for the online evaluation of the station frequency regulation was proposed based on the benchmark governor fitting.This method helps in overcoming the capacity-based reserve static setting.Finally,an optimization model was developed,along with the proposal of the linearized solving algorithm.The field data from the JH4#station in China’s MX power grid was considered for validation.The proposed method achieves a 24.77%increase in the station income while ensuring the system frequency stability when compared with the grid code-based method.展开更多
An improved method for stabilizing a frequency-quadrupled 214.5-nm tunable diode laser system is re- ported. Improvements to the method include a homemade logic circuit and the use of a Fabry-Perot optical spectrum an...An improved method for stabilizing a frequency-quadrupled 214.5-nm tunable diode laser system is re- ported. Improvements to the method include a homemade logic circuit and the use of a Fabry-Perot optical spectrum analyzer as a transfer cavity. Lasers locked with this method exhibit megahertz-level frequency stability measured with an optical frequency comb referenced to a cesium atomic standard. The laser can be locked for hours to days, depending on experiment requirements. Being relatively inexpensive, stable, and robust, the control method can be applied to stabilizing essentially all lasers of deep ultraviolet wavelengths.展开更多
Polarization spectra of rubidium atoms were investigated with different uncrossed angles between the polarizer and the analyzer. The variation of the spectra was derived theoretically as a function of arbitrary angle,...Polarization spectra of rubidium atoms were investigated with different uncrossed angles between the polarizer and the analyzer. The variation of the spectra was derived theoretically as a function of arbitrary angle, and measured experimentally for different angles. The spectral profile of D2 line of rubidium was further used to stabilize the frequency of a diode laser. It was demonstrated that the laser linewidth was reduced to 2 MHz.展开更多
A frequency-stabilized 556-nm laser is an essential tool for experimental studies associated with ^1S0-^3p1 intercombination transition of ytterbium （Yb） atoms. A 556-nm laser light using a single-pass second harmon...A frequency-stabilized 556-nm laser is an essential tool for experimental studies associated with ^1S0-^3p1 intercombination transition of ytterbium （Yb） atoms. A 556-nm laser light using a single-pass second harmonic generation （SHG） is obtained in a periodically poled MgO：LiNbO3 （PPLN） crystal pumped by a fiber laser at 1111.6 nm. A robust frequency stabilization method which facilitates the control of laser frequency with an accuracy better than the natural linewidth （187 kHz） of the intercombination line is developed. The short-term frequency jitter is reduced to less than 100 kHz by locking the laser to a home-made reference cavity. A slow frequency drift is sensed by the 556-nm fluorescence signal of an Yb atomic beam excited by one probe beam and is reduced to less than 50-kHz by a computer-controlled servo system. The laser can be stably locked for more than 5 h. This frequency stabilization method can be extended to other alkaline-earth-like atoms with similar weak intercombination lines.展开更多
The frequency of an external-cavity diode laser has been stabilized to 1.637 μm by using the reference of absorption lines of methane. The method can be applied to wavelength division multiplexed optical communicatio...The frequency of an external-cavity diode laser has been stabilized to 1.637 μm by using the reference of absorption lines of methane. The method can be applied to wavelength division multiplexed optical communication, fiber-optic sensing systems, as well as the high-sensitivity detection of methane. The derivative-like error signal yielded by frequency modulation and phase sensitivity detection technology is inputted into the PI feedback loop circuit in order to stabilize the frequency to the line center. After stabilization, the frequency fluctuation of diode laser is held within 5.6 MHz, and the root of Allan variance of error signal reaches a minimum of 1.66×10-10 for an average time of 10 s.展开更多
We demonstrate a tunable wavelength-locked seed laser source with high-frequency stability to realize the precise measurements of global atmospheric wind field. An Nd：YAG laser at 1 064 nm is used as the master laser...We demonstrate a tunable wavelength-locked seed laser source with high-frequency stability to realize the precise measurements of global atmospheric wind field. An Nd：YAG laser at 1 064 nm is used as the master laser （ML）. Its frequency is locked to a confocal Fabry-Perot interferometer by using the Pound-Drever- Hall method, which ensures the peak-to-peak value of its frequency drifts less than 180 kHz over 2 h. Another Nd：YAG laser at 1 064 nm, as the slave laser, is offset-locked to the above ML using optical phase locked loop, retaining virtually the same absolute frequency stability as the ML. The tunable ranges of the frequency differences between two lasers are up to 3 OHz, and the tuning step length was an arbitrary integral multiple of 200 kHz. The researched seed laser source is compact and robust, which can well satisfy the requirement of the Doppler wind lidar.展开更多
The interaction between polychromatic fields and atoms is an important subject in quantum optics.Frequency locking for small frequency interval multi-field is usually required in some experiments.In this letter,we exp...The interaction between polychromatic fields and atoms is an important subject in quantum optics.Frequency locking for small frequency interval multi-field is usually required in some experiments.In this letter,we experimentally demonstrate a holistic scheme for bichromatic laser frequency stabilization.Compared with traditional saturation absorption methods and complicated frequency shift schemes,offset locking for bichromatic fields is simply achieved using polarization spectroscopy and Doppler effect.Frequency locking with a wide-range asymmetry of the detuning is also shown.Our scheme makes laser spectroscopy experiments with polychromatic fields more convenient.展开更多
A single-frequency passively Q-switched laser was constructed, in which a co-doped crystal served as an active element, a mode selector, and a passive Q-switch simultaneously. In order to obtain the frequency instabil...A single-frequency passively Q-switched laser was constructed, in which a co-doped crystal served as an active element, a mode selector, and a passive Q-switch simultaneously. In order to obtain the frequency instability of 10^-6, a stable single-frequency operation was presented and its characteristics were determined. The experimental results showed that the stable single frequency could be maintained for half an hour and the linewidth was approximately 530 MHz at a pump power of 13 W.展开更多
Power electronic-interfaced renewable energy sources(RES)exhibit lower inertia compared to traditional synchronous generators.The large-scale integration of RES has led to a significant reduction in system inertia,pos...Power electronic-interfaced renewable energy sources(RES)exhibit lower inertia compared to traditional synchronous generators.The large-scale integration of RES has led to a significant reduction in system inertia,posing significant challenges for maintaining frequency stability in future power systems.This issue has garnered considerable attention in recent years.However,the existing research has not yet achieved a comprehensive understanding of system inertia and frequency stability in the context of low-inertia systems.To this end,this paper provides a comprehensive review of the definition,modeling,analysis,evaluation,and control for frequency stability.It commences with an exploration of inertia and frequency characteristics in low-inertia systems,followed by a novel definition of frequency stability.A summary of frequency stability modeling,analysis,and evaluation methods is then provided,along with their respective applicability in various scenarios.Additionally,the two critical factors of frequency control—energy sources at the system level and control strategies at the device level—are examined.Finally,an outlook on future research in low-inertia power systems is discussed.展开更多
A new method for laser-frequency stabilization by controlling the pulse setup time is presented. The frequency-stabilization system monitors the pulse setup time continuously, and controls it by adjusting the cavity l...A new method for laser-frequency stabilization by controlling the pulse setup time is presented. The frequency-stabilization system monitors the pulse setup time continuously, and controls it by adjusting the cavity length. Laser frequency is stabilized to the center of the gain curve when the setup time is the shortest. The system is used to stabilize a radio-frequency-excited waveguide CO2 laser tuned by grating, and the shift of laser frequency is estimated to be less than ±25 MHz for an extended period. The system has the advantages of compact structure, small volume, and low cost. It can be applied for frequency stabilization of other kinds of pulsed lasers with adjustable cavity.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.10774044)the National Key Basic Research and Development Program of China(Grant No.2010CB922903)+1 种基金the Science and Technology Commission of Shanghai Municipality of China(Grant No.07JC14019)Shanghai Pujiang Talent Program of China(Grant No.07PJ14038)
文摘The modulation transfer spectroscopy in an ytterbium hollow cathode lamp at 399 nm is measured. The error signal for frequency locking is optimized by measuring the dependences of its slope, linewidth and magnitude on various parameters. Under the optimum condition, the laser frequency at 399 nm can be stabilized. The long-term stability of laser frequency is measured by monitoring the fluorescence signal of the ytterbium atomic beam induced by the locked laser. The laser frequency is shown to be tightly locked, and the stabilized laser is successfully applied to the cooling of ytterbium atoms.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB921603)the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(Grant No.IRT13076)+4 种基金the Major Research Plan of the National Natural Science Foundation of China(Grant No.91436108)the National Natural Science Foundation of China(Grant Nos.61378014,61308023,61378015,and 11434007)the Fund for Fostering Talents in Basic Science of the National Natural Science Foundation of China(Grant No.J1103210)the New Teacher Fund of the Ministry of Education of China(Grant No.20131401120012)the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.2013021005-1)
文摘We report a robust method of directly stabilizing a grating feedback diode laser to an arbitrary frequency in a large range. The error signal, induced from the difference between the frequency measured by a wavelength meter and the preset target frequency, is fed back to the piezoelectric transducer module of the diode laser via a sound card in the computer. A visual Labview procedure is developed to realize a feedback system. In our experiment the frequency drift of the diode laser is reduced to 8 MHz within 25 min. The robust scheme can be adapted to realize the arbitrary frequency stabilization for many other kinds of lasers.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11704408 and 91836106)the Beijing Natural Science Foundation,China(Grant No.Z180013)the Joint Fund of the Ministry of Education,China(Grant No.6141A020333xx).
文摘We develop a high-performance ultraviolet(UV)frequency stabilization technique implemented directly on UV diode lasers by combining the dichroic atomic vapor laser lock and the resonant transfer cavity lock.As an example,we demonstrate a stable locking with measured frequency standard deviations of approximately 200 kHz and 300 kHz for 399 nm and 370 nm diode lasers in 20 min.We achieve a long-term frequency drift of no more than 1 MHz for the target 370 nm laser within an hour,which is further verified with fluorescence count rates of a single trapped ^171Yb+ion.We also find strong linear correlations between lock points and environmental factors such as temperature and atmospheric pressure.Our approach provides a simple and stable solution at a relatively low cost,and features flexible control,high feedback bandwidth and minimal power consumption of the target UV laser.
基金Supported by the National Fundamental Research Program of China under Grant No 2011CB921501the National Natural Science Foundation of China under Grant Nos 91336103,10934010 and 61078026
文摘A method is presented to improve the laser frequency stabilization for the optical pumping cesium clock. By comparing the laser frequency stabilization of different schemes, we verify that the light angle is an important factor that limits the long-term frequency stability. We minimize the drift of the light angle by using a fiber- coupled output, and lock the frequency of a distributed-feedback diode laser to the fluorescence spectrum of the atomic beam. The measured frequency stability is about 3.5 ×10^-11 at i s and reaches 1.5 × 10^-12 at 2000s. The Allan variance keeps going down for up to thousands of seconds, indicating that the medium- and long-term stability of the laser frequency is significantly improved and perfectly fulfills the requirement for the optical pumping cesium clock.
基金Supported by the National Natural Science Foundation of China(61227805,11574352,91536104,91636215)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB21030700)
文摘We report laser frequency stabilization with modulation transfer spectroscopy（MTS） on 85 Rb atoms. With both PZT（piezo-electric transducer） slow-loop feedback and current fastloop feedback to the laser head, we get a linewidth narrowing less than 5 kHz simultaneously. Laser injection to a laser diode and frequency beating with another polarization spectroscopy based stabilization setup are also employed to check the narrow linewidth property. With the help of the technique, a linewidth around k Hz-level laser is obtained and pave the way for the locking of the lattice laser of ytterbium clock with transfer cavity technique. The setup can be used as a frequency reference for precise frequency control of atomic clock system.
基金supported by the Fundamental Research Funds for the Central Universities(No.KG21008401).
文摘Atomic spectroscopy serves as the basis for quantum precision measurements,where frequency-stabilized lasers are crucial for obtaining accurate atomic spectra.This work introduces a compact laser frequency stabilization system that employs a multifunctional metasurface to adjust the polarization,amplitude,and propagation direction of incident light.By combining with a Rb atomic vapor cell,the system achieves a tunable sub-Doppler spectrum for laser frequency stabilization.The experimental result demonstrates that a laser frequency stability of 3×10−11 is attained from 1 to 200 s at 780 nm with the input power at 20µW.The devices hold significant potential for compactness,integration,and mass production,making them highly suitable for quantum measurement applications.
基金supported by the National Natural Science Foundation of China(Nos.11874371,91436105,and 12104474)the Shanghai Science and Technology Program,China(No.22ZR1471000)the Strategic Pilot Science and Technology Project of the Chinese Academy of Sciences,China(No.XDB21030200)。
文摘A simple and robust multiple wavelength frequency stabilization system is demonstrated using a single transfer cavity and a1062-nm ultra-stable laser for all the lasers used in a mercury optical lattice clock.Offset sideband locking is employed to tune the laser frequency while dichroic mirrors and differentiated modulation frequencies are utilized for the Pound–Drever–Hall locking of four-color lasers.For the most demanding lasers at 1015 nm and 725 nm,the line width of the beat note is reduced to 27 kHz and 17 kHz,respectively.The frequency fluctuation for the transfer-locked 1015-nm laser is less than 10 kHz,which is much better than the lasers locked to an atomic spectrum.Using its high stability of 5×10^(-12)over100 s,the transfer-locked 1015-nm laser is employed for low-noise frequency modulated saturated absorption spectroscopy.This approach could also be used in various situations for the research of optical clocks,Rydberg atoms,laser cooling of molecules,and quantum computation with neutral atoms.
基金the National Natural Science Foundation of China(No.62305354)。
文摘In this study,a miniature laser frequency stabilization module for cold atom sensing applications was designed and realized.The module can lock the laser frequency to the saturated absorption spectrum of the D2 line of rubidium(Rb)atoms using the frequency modulation spectroscopy method.The module core is a tiny Rb cell,co-packaged with the saturation absorption optical setup,temperature control circuit,and detection circuit through a joint optical-mechanical-electrical design for a total volume of only 40 mm×15 mm×30 mm.The frequency fluctuation of the 780 nm laser after frequency stabilization by the module was within 1 MHz over 1000 s,which is adequate for magneto-optical trap experiments.The results verify the feasibility of the module as a frequency reference and provide a light source for portable cold atom sensing devices.
基金Project supported by the National Ministry of Science and Technology and Key Research Project 973(Nos.2014CB340102,2017YFF0104601)the Preeminence Youth Fund of China(No.61625504)the National Natural Science Foundation of China(Nos.61527820,11674313,61535014,61727815)
文摘The frequency stability of free-running semiconductor lasers is influenced by several factors, such as driving current and external operating environment. The frequency stabilization of laser has become an international research hotspot in recent years. This paper reviews active frequency stabilization technologies of laser diodes and elaborates their principles. Based on differences of frequency discrimination curves, these active frequency stabilization technologies are classified into three major types, which are harmonic frequency stabilization,Pound-Drever-Hall(PDH) technology and curve subtraction frequency stabilization. Further, merits and demerits of each technology are compared from aspects of frequency stability and structure complexity. Finally, prospects of frequency stabilization technologies of semiconductor lasers are discussed in detail. Combining several of these methods are future trends, especially the combination of frequency stabilization of F–P cavity. And PID electronic control for optimizing the servo system is generally added in the methods mentioned above.
基金funded by the Technology Project of State Grid Corporation of China(Research on Safety and Stability Evaluation and Optimization Enhancement Technology of Flexible Ultra High Voltage Multiterminal DC System Adapting to the Background of“Sand and Gobi Deserts”),grant number J2024003。
文摘Countries worldwide are advocating for energy transition initiatives to promote the construction of low-carbon energy systems.The low voltage ride through(LVRT)characteristics of renewable energy units and commutation failures in line commutated converter high voltage direct current(LCC-HVDC)systems at the receiving end leads to short-term power shortage(STPS),which differs from traditional frequency stability issues.STPS occurs during the generator’s power angle swing phase,before the governor responds,and is on a timescale that is not related to primary frequency regulation.This paper addresses these challenges by examining the impact of LVRT on voltage stability,developing a frequency response model to analyze the mechanism of frequency instability caused by STPS,deriving the impact of STPS on the maximum frequency deviation,and introducing an energy deficiency factor to assess its impact on regional frequency stability.The East China Power Grid is used as a case study,where the energy deficiency factor is calculated to validate the proposed mechanism.STPS is mainly compensated by the rotor kinetic energy of the generators in this region,with minimal impact on other regions.It is concluded that the energy deficiency factor provides an effective explanation for the spatial distribution of the impact of STPS on system frequency.
基金supported by the Scientific Research Project of China Three Gorges Group Co.LTD(Contract Number:202103368).
文摘The frequency regulation reserve setting of wind-PV-storage power stations is crucial.However,the existing grid codes set up the station reserve in a static manner,where the synchronous generator characteristics and frequency-step disturbance scenario are considered.Thus,the advantages of flexible regulation of renewable generations are wasted,resulting in excessive curtailment of wind and solar resources.In this study,a method for optimizing the frequency regulation reserve of wind PV storage power stations was developed.Moreover,a station frequency regulation model was constructed,considering the field dynamic response and the coupling between the station and system frequency dynamics.Furthermore,a method for the online evaluation of the station frequency regulation was proposed based on the benchmark governor fitting.This method helps in overcoming the capacity-based reserve static setting.Finally,an optimization model was developed,along with the proposal of the linearized solving algorithm.The field data from the JH4#station in China’s MX power grid was considered for validation.The proposed method achieves a 24.77%increase in the station income while ensuring the system frequency stability when compared with the grid code-based method.
基金supported by the National "973" Program of China(No.2010CB922901)the Tsinghua University Scientific Research Initiative Program(No.20091081474)
文摘An improved method for stabilizing a frequency-quadrupled 214.5-nm tunable diode laser system is re- ported. Improvements to the method include a homemade logic circuit and the use of a Fabry-Perot optical spectrum analyzer as a transfer cavity. Lasers locked with this method exhibit megahertz-level frequency stability measured with an optical frequency comb referenced to a cesium atomic standard. The laser can be locked for hours to days, depending on experiment requirements. Being relatively inexpensive, stable, and robust, the control method can be applied to stabilizing essentially all lasers of deep ultraviolet wavelengths.
基金This work was supported by the National Natural Science Foundation of China under Grant No. 10104018.
文摘Polarization spectra of rubidium atoms were investigated with different uncrossed angles between the polarizer and the analyzer. The variation of the spectra was derived theoretically as a function of arbitrary angle, and measured experimentally for different angles. The spectral profile of D2 line of rubidium was further used to stabilize the frequency of a diode laser. It was demonstrated that the laser linewidth was reduced to 2 MHz.
基金supported by the National Natural Science Foundation of China (Nos. 10634060 and 10904161) the National Key Basic Research and Development Program of China (No. 2006CB921406)
文摘A frequency-stabilized 556-nm laser is an essential tool for experimental studies associated with ^1S0-^3p1 intercombination transition of ytterbium （Yb） atoms. A 556-nm laser light using a single-pass second harmonic generation （SHG） is obtained in a periodically poled MgO：LiNbO3 （PPLN） crystal pumped by a fiber laser at 1111.6 nm. A robust frequency stabilization method which facilitates the control of laser frequency with an accuracy better than the natural linewidth （187 kHz） of the intercombination line is developed. The short-term frequency jitter is reduced to less than 100 kHz by locking the laser to a home-made reference cavity. A slow frequency drift is sensed by the 556-nm fluorescence signal of an Yb atomic beam excited by one probe beam and is reduced to less than 50-kHz by a computer-controlled servo system. The laser can be stably locked for more than 5 h. This frequency stabilization method can be extended to other alkaline-earth-like atoms with similar weak intercombination lines.
基金This work was supported by the National Basic Research Priorities Programme (2002ccc02500).
文摘The frequency of an external-cavity diode laser has been stabilized to 1.637 μm by using the reference of absorption lines of methane. The method can be applied to wavelength division multiplexed optical communication, fiber-optic sensing systems, as well as the high-sensitivity detection of methane. The derivative-like error signal yielded by frequency modulation and phase sensitivity detection technology is inputted into the PI feedback loop circuit in order to stabilize the frequency to the line center. After stabilization, the frequency fluctuation of diode laser is held within 5.6 MHz, and the root of Allan variance of error signal reaches a minimum of 1.66×10-10 for an average time of 10 s.
基金supported by the National Natural Science Foundation of China (Nos. 61108028 and 61178031)Project of Shandong Academy of Information and Communication Technology Introducing High Level Personals from Home and Abroad
文摘We demonstrate a tunable wavelength-locked seed laser source with high-frequency stability to realize the precise measurements of global atmospheric wind field. An Nd：YAG laser at 1 064 nm is used as the master laser （ML）. Its frequency is locked to a confocal Fabry-Perot interferometer by using the Pound-Drever- Hall method, which ensures the peak-to-peak value of its frequency drifts less than 180 kHz over 2 h. Another Nd：YAG laser at 1 064 nm, as the slave laser, is offset-locked to the above ML using optical phase locked loop, retaining virtually the same absolute frequency stability as the ML. The tunable ranges of the frequency differences between two lasers are up to 3 OHz, and the tuning step length was an arbitrary integral multiple of 200 kHz. The researched seed laser source is compact and robust, which can well satisfy the requirement of the Doppler wind lidar.
基金supported by the National Basic Research Program of China(Nos. 2003CB724505/1 and 2006CB921203)the National Natural Science Foundation of China(No. 10774160)the Wuhan National Laboratory for Optoelectronics(No. P080001)
文摘The interaction between polychromatic fields and atoms is an important subject in quantum optics.Frequency locking for small frequency interval multi-field is usually required in some experiments.In this letter,we experimentally demonstrate a holistic scheme for bichromatic laser frequency stabilization.Compared with traditional saturation absorption methods and complicated frequency shift schemes,offset locking for bichromatic fields is simply achieved using polarization spectroscopy and Doppler effect.Frequency locking with a wide-range asymmetry of the detuning is also shown.Our scheme makes laser spectroscopy experiments with polychromatic fields more convenient.
基金This work was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences, and the National High Technology Development Program of China (No. 2002AA311120 and 2002AA311040).
文摘A single-frequency passively Q-switched laser was constructed, in which a co-doped crystal served as an active element, a mode selector, and a passive Q-switch simultaneously. In order to obtain the frequency instability of 10^-6, a stable single-frequency operation was presented and its characteristics were determined. The experimental results showed that the stable single frequency could be maintained for half an hour and the linewidth was approximately 530 MHz at a pump power of 13 W.
基金supported by the National Natural Science Foundation of China(U2166601)。
文摘Power electronic-interfaced renewable energy sources(RES)exhibit lower inertia compared to traditional synchronous generators.The large-scale integration of RES has led to a significant reduction in system inertia,posing significant challenges for maintaining frequency stability in future power systems.This issue has garnered considerable attention in recent years.However,the existing research has not yet achieved a comprehensive understanding of system inertia and frequency stability in the context of low-inertia systems.To this end,this paper provides a comprehensive review of the definition,modeling,analysis,evaluation,and control for frequency stability.It commences with an exploration of inertia and frequency characteristics in low-inertia systems,followed by a novel definition of frequency stability.A summary of frequency stability modeling,analysis,and evaluation methods is then provided,along with their respective applicability in various scenarios.Additionally,the two critical factors of frequency control—energy sources at the system level and control strategies at the device level—are examined.Finally,an outlook on future research in low-inertia power systems is discussed.
基金supported by the National Natural Science Foundation of China (No.60668016)the New Century Foundation for Talents of the Ministry of Education of China (No.NCET-07-0240)+2 种基金the Fundamental Research Funds for the Central Universities (No.HIT.BRET.2010014)the Science and Technology Planning of Shandong Province,China (No.2009GG10005006)the Funds for National Key Laboratory of Tunable Laser Technology of China
文摘A new method for laser-frequency stabilization by controlling the pulse setup time is presented. The frequency-stabilization system monitors the pulse setup time continuously, and controls it by adjusting the cavity length. Laser frequency is stabilized to the center of the gain curve when the setup time is the shortest. The system is used to stabilize a radio-frequency-excited waveguide CO2 laser tuned by grating, and the shift of laser frequency is estimated to be less than ±25 MHz for an extended period. The system has the advantages of compact structure, small volume, and low cost. It can be applied for frequency stabilization of other kinds of pulsed lasers with adjustable cavity.
