A maximum of 5.5 W of cw TEM_(00) mode output at 532nm has been obtained by intracavity frequency doubling with a KTP crystal in an Nd:YVO_(4) laser doubly-pumped with 20 W diode pumping power.The optical-optical conv...A maximum of 5.5 W of cw TEM_(00) mode output at 532nm has been obtained by intracavity frequency doubling with a KTP crystal in an Nd:YVO_(4) laser doubly-pumped with 20 W diode pumping power.The optical-optical conversion efficiency is 27.5%.The influence of thermal lensing at high pumping power in the end-pumped Nd:YVO_(4) laser is discussed.The Nd:YVO_(4) laser has a good power stability of 1.6%.展开更多
We report the nonlocal imaging of an object by conditional averaging of the random exposure frames of a reference detector,which only sees the freely propagating field from a thermal light source.A bucket detector,syn...We report the nonlocal imaging of an object by conditional averaging of the random exposure frames of a reference detector,which only sees the freely propagating field from a thermal light source.A bucket detector,synchronized with the reference detector,records the intensity fluctuations of an identical beam passing through the object mask.These fluctuations are sorted according to their values relative to the mean,then the reference data in the corresponding time-bins for a given fluctuation range are averaged,to produce either positive or negative images.Since no correlation calculations are involved,this correspondence imaging technique challenges our former interpretations of “ghost” imaging.Compared with conventional correlation imaging or compressed sensing schemes,both the number of exposures and computation time are greatly reduced,while the visibility is much improved.A simple statistical model is presented to explain the phenomenon.展开更多
The performance of a passively Q-switched all-solid-state Nd:YVO_(4) laser using Cr^(4+):YAG as saturable absorber is reported.Optimum coupling operation at 1064nm resulted in 70ns pulses at 40kHz repetition rates wit...The performance of a passively Q-switched all-solid-state Nd:YVO_(4) laser using Cr^(4+):YAG as saturable absorber is reported.Optimum coupling operation at 1064nm resulted in 70ns pulses at 40kHz repetition rates with average output power of 2.1 W.A quantitative theoretical description agrees well with the experimental results.展开更多
We have demonstrated a diode-pumped Nd:YVO4 laser that produced 273mW cw output at 671 nm by using KTP intracavity doubling.The optical-optical efficiency of the all-solid-state red laser was 5.1%.The maximum output p...We have demonstrated a diode-pumped Nd:YVO4 laser that produced 273mW cw output at 671 nm by using KTP intracavity doubling.The optical-optical efficiency of the all-solid-state red laser was 5.1%.The maximum output power of the fundamental wave at 1342nm from Nd:YVO_(4) was 2.3W with slope-efficiency of 43%.展开更多
The retracing behavior of the phase-matching angle(RBPA)in many nonlinear optical crystals for second harmonic generation(SHG)has been demonstrated by calculation.The generality of this phenomenon is successfully expl...The retracing behavior of the phase-matching angle(RBPA)in many nonlinear optical crystals for second harmonic generation(SHG)has been demonstrated by calculation.The generality of this phenomenon is successfully explained by a theoretical analysis based on classical optics.The wavelengths of the fundamental waves and phasematching angles for describing the RBPA of eight kinds of crystals are presented.Furthermore,we point out that RBPA exists generally in both uniaxial and biaxial crystals for both type Ⅰ and type Ⅱ SHG.展开更多
With a type-I noncritically phase-matched LiB_(3)O_(5) crystal as the intracavity frequency doubler in a diode pumped Nd:YVO_(4) laser,440mW of 671 nm light was obtained at 5.5W of incident pump power,the optical-opti...With a type-I noncritically phase-matched LiB_(3)O_(5) crystal as the intracavity frequency doubler in a diode pumped Nd:YVO_(4) laser,440mW of 671 nm light was obtained at 5.5W of incident pump power,the optical-optical conversion efficiency being 8.0%.展开更多
We report a new type of optical parametric oscillator(OPO)cavity,i.e.,a compound cavity OPO.Both the numerical simulation and experimental results show that this type of cavity is superior,in that its threshold is low...We report a new type of optical parametric oscillator(OPO)cavity,i.e.,a compound cavity OPO.Both the numerical simulation and experimental results show that this type of cavity is superior,in that its threshold is lower than that of a simple narrow-band cavity with dispersive elements,and its external efficiency is increased while its narrow linewidth remains nearly the same across the tunable range of the nonlinear crystals used.展开更多
We present a study of the generation of squeezed states through nonlinear three-wave mixing in media with an intensity-dependent index of refraction.In the semiclassical model,perfect squeezing for combination modes c...We present a study of the generation of squeezed states through nonlinear three-wave mixing in media with an intensity-dependent index of refraction.In the semiclassical model,perfect squeezing for combination modes can be generated.Using the Fokker-Planck equation approach,the effects of pump(including squeezed pump)and loss are discussed.It is shown that the fluctuations of the pump place no fundamental limit to the degree of squeezing obtainable but losses do give an absolute limit.展开更多
Phase conjugation in degenerate four-wave mixing with a squeezed input beam is investigated.We show that the phase conjugate mode is always super-Poissonian and never squeezed,but the combination mode may be squeezed ...Phase conjugation in degenerate four-wave mixing with a squeezed input beam is investigated.We show that the phase conjugate mode is always super-Poissonian and never squeezed,but the combination mode may be squeezed to an extent even greater than the input probe wave.展开更多
In the centenary year of Einstein's General Theory of Relativity, this paper reviews the current status of gravitational wave astronomy across a spectrum which stretches from attohertz to kilohertz frequencies. Se...In the centenary year of Einstein's General Theory of Relativity, this paper reviews the current status of gravitational wave astronomy across a spectrum which stretches from attohertz to kilohertz frequencies. Sect. 1 of this paper reviews the historical development of gravitational wave astronomy from Einstein's first prediction to our current understanding the spectrum. It is shown that detection of signals in the audio frequency spectrum can be expected very soon, and that a north-south pair of next generation detectors would provide large scientific benefits. Sect. 2 reviews the theory of gravitational waves and the principles of detection using laser interferometry. The state of the art Advanced LIGO detectors are then described. These detectors have a high chance of detecting the first events in the near future. Sect. 3 reviews the KAGRA detector currently under development in Japan,which will be the first laser interferometer detector to use cryogenic test masses. Sect. 4 of this paper reviews gravitational wave detection in the nanohertz frequency band using the technique of pulsar timing. Sect. 5 reviews the status of gravitational wave detection in the attohertz frequency band, detectable in the polarisation of the cosmic microwave background, and discusses the prospects for detection of primordial waves from the big bang. The techniques described in sects. 1–5 have already placed significant limits on the strength of gravitational wave sources. Sects. 6 and 7 review ambitious plans for future space based gravitational wave detectors in the millihertz frequency band. Sect. 6 presents a roadmap for development of space based gravitational wave detectors by China while sect. 7 discusses a key enabling technology for space interferometry known as time delay interferometry.展开更多
This paper focuses on the next detectors for gravitational wave astronomy which will be required after the current ground based detectors have completed their initial observations, and probably achieved the first dire...This paper focuses on the next detectors for gravitational wave astronomy which will be required after the current ground based detectors have completed their initial observations, and probably achieved the first direct detection of gravitational waves. The next detectors will need to have greater sensitivity, while also enabling the world array of detectors to have improved angular resolution to allow localisation of signal sources. Sect. 1 of this paper begins by reviewing proposals for the next ground based detectors,and presents an analysis of the sensitivity of an 8 km armlength detector, which is proposed as a safe and cost-effective means to attain a 4-fold improvement in sensitivity. The scientific benefits of creating a pair of such detectors in China and Australia is emphasised. Sect. 2 of this paper discusses the high performance suspension systems for test masses that will be an essential component for future detectors, while sect. 3 discusses solutions to the problem of Newtonian noise which arise from fluctuations in gravity gradient forces acting on test masses. Such gravitational perturbations cannot be shielded, and set limits to low frequency sensitivity unless measured and suppressed. Sects. 4 and 5 address critical operational technologies that will be ongoing issues in future detectors. Sect. 4 addresses the design of thermal compensation systems needed in all high optical power interferometers operating at room temperature. Parametric instability control is addressed in sect. 5. Only recently proven to occur in Advanced LIGO, parametric instability phenomenon brings both risks and opportunities for future detectors. The path to future enhancements of detectors will come from quantum measurement technologies. Sect. 6 focuses on the use of optomechanical devices for obtaining enhanced sensitivity, while sect. 7 reviews a range of quantum measurement options.展开更多
基金Supported by the National Advanced Materials Committee of the"863 Program"under Grant No.970311043。
文摘A maximum of 5.5 W of cw TEM_(00) mode output at 532nm has been obtained by intracavity frequency doubling with a KTP crystal in an Nd:YVO_(4) laser doubly-pumped with 20 W diode pumping power.The optical-optical conversion efficiency is 27.5%.The influence of thermal lensing at high pumping power in the end-pumped Nd:YVO_(4) laser is discussed.The Nd:YVO_(4) laser has a good power stability of 1.6%.
基金Supported by the National Natural Science Foundation of China under Grant No 60978002the National Basic Research Program of China under Grant Nos 2010CB922904 and 2007CB814800the National High Technology R&D Program of China under Grant No 2011AA120102。
文摘We report the nonlocal imaging of an object by conditional averaging of the random exposure frames of a reference detector,which only sees the freely propagating field from a thermal light source.A bucket detector,synchronized with the reference detector,records the intensity fluctuations of an identical beam passing through the object mask.These fluctuations are sorted according to their values relative to the mean,then the reference data in the corresponding time-bins for a given fluctuation range are averaged,to produce either positive or negative images.Since no correlation calculations are involved,this correspondence imaging technique challenges our former interpretations of “ghost” imaging.Compared with conventional correlation imaging or compressed sensing schemes,both the number of exposures and computation time are greatly reduced,while the visibility is much improved.A simple statistical model is presented to explain the phenomenon.
基金Supported by the 863 Program of National Advanced Materials Committee
文摘The performance of a passively Q-switched all-solid-state Nd:YVO_(4) laser using Cr^(4+):YAG as saturable absorber is reported.Optimum coupling operation at 1064nm resulted in 70ns pulses at 40kHz repetition rates with average output power of 2.1 W.A quantitative theoretical description agrees well with the experimental results.
基金Supported by the National Advanced Materials Commit tee of the“863 Program”(863-715-001-00).
文摘We have demonstrated a diode-pumped Nd:YVO4 laser that produced 273mW cw output at 671 nm by using KTP intracavity doubling.The optical-optical efficiency of the all-solid-state red laser was 5.1%.The maximum output power of the fundamental wave at 1342nm from Nd:YVO_(4) was 2.3W with slope-efficiency of 43%.
基金the High Technology Research and Development Programme of China.
文摘The retracing behavior of the phase-matching angle(RBPA)in many nonlinear optical crystals for second harmonic generation(SHG)has been demonstrated by calculation.The generality of this phenomenon is successfully explained by a theoretical analysis based on classical optics.The wavelengths of the fundamental waves and phasematching angles for describing the RBPA of eight kinds of crystals are presented.Furthermore,we point out that RBPA exists generally in both uniaxial and biaxial crystals for both type Ⅰ and type Ⅱ SHG.
基金Supported by the National Advanced Materials Commit tee of the"863 Program"under Grant No.863-715-001-00.
文摘With a type-I noncritically phase-matched LiB_(3)O_(5) crystal as the intracavity frequency doubler in a diode pumped Nd:YVO_(4) laser,440mW of 671 nm light was obtained at 5.5W of incident pump power,the optical-optical conversion efficiency being 8.0%.
基金Supported by the National Natural Science Foundation of China under Grant No.69678005the“863”Program(715-001-0020)of China。
文摘We report a new type of optical parametric oscillator(OPO)cavity,i.e.,a compound cavity OPO.Both the numerical simulation and experimental results show that this type of cavity is superior,in that its threshold is lower than that of a simple narrow-band cavity with dispersive elements,and its external efficiency is increased while its narrow linewidth remains nearly the same across the tunable range of the nonlinear crystals used.
基金Supported by the National Natural Science Foundation of China under Grant No.19574030。
文摘We present a study of the generation of squeezed states through nonlinear three-wave mixing in media with an intensity-dependent index of refraction.In the semiclassical model,perfect squeezing for combination modes can be generated.Using the Fokker-Planck equation approach,the effects of pump(including squeezed pump)and loss are discussed.It is shown that the fluctuations of the pump place no fundamental limit to the degree of squeezing obtainable but losses do give an absolute limit.
基金Supported by the National Natural Science Foundation of China and the Third World Academy of Sciences.
文摘Phase conjugation in degenerate four-wave mixing with a squeezed input beam is investigated.We show that the phase conjugate mode is always super-Poissonian and never squeezed,but the combination mode may be squeezed to an extent even greater than the input probe wave.
基金supported by the US National Science Foundation(Grant No.PHY-0757058)supported by the National Natural Science Foundation of China(Grant Nos.11443008 and 11503003)+2 种基金a Returned Overseas Chinese Scholars Foundation grant,and Fundamental Research Funds for the Central Universities(Grant No.2015KJJCB06)supported by the National Space Science Center,Chinese Academy of Sciences(Grant Nos.XDA04070400 and XDA04077700)Partial supports from the National Natural Science Foundation of China(Grant Nos.11305255,11171329 and 41404019)
文摘In the centenary year of Einstein's General Theory of Relativity, this paper reviews the current status of gravitational wave astronomy across a spectrum which stretches from attohertz to kilohertz frequencies. Sect. 1 of this paper reviews the historical development of gravitational wave astronomy from Einstein's first prediction to our current understanding the spectrum. It is shown that detection of signals in the audio frequency spectrum can be expected very soon, and that a north-south pair of next generation detectors would provide large scientific benefits. Sect. 2 reviews the theory of gravitational waves and the principles of detection using laser interferometry. The state of the art Advanced LIGO detectors are then described. These detectors have a high chance of detecting the first events in the near future. Sect. 3 reviews the KAGRA detector currently under development in Japan,which will be the first laser interferometer detector to use cryogenic test masses. Sect. 4 of this paper reviews gravitational wave detection in the nanohertz frequency band using the technique of pulsar timing. Sect. 5 reviews the status of gravitational wave detection in the attohertz frequency band, detectable in the polarisation of the cosmic microwave background, and discusses the prospects for detection of primordial waves from the big bang. The techniques described in sects. 1–5 have already placed significant limits on the strength of gravitational wave sources. Sects. 6 and 7 review ambitious plans for future space based gravitational wave detectors in the millihertz frequency band. Sect. 6 presents a roadmap for development of space based gravitational wave detectors by China while sect. 7 discusses a key enabling technology for space interferometry known as time delay interferometry.
基金the support of the United States National Science Foundation for the construction and operation of the LIGO Laboratory and the Science and Technology Facilities Council of the United Kingdomthe MaxPlanck-Society,and the State of Niedersachsen/Germany for support of the construction and operation of the GEO600 detector+4 种基金the support of the research by these agencies and by the Australian Research Council,the Council of Scientific and Industrial Research of Indiathe Alfred P.Sloan Foundation.S.H.acknowledges the support from the European Research Council(ERC-2012-St G:307245)supported by the LSC LIGO visitor program,the Australian Department of Education and Australian Research Councilalso supported by Australian Research Council(Grant Nos.DP120100898 and DP120104676)LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation,and operates under cooperative agreement PHY-0757058
文摘This paper focuses on the next detectors for gravitational wave astronomy which will be required after the current ground based detectors have completed their initial observations, and probably achieved the first direct detection of gravitational waves. The next detectors will need to have greater sensitivity, while also enabling the world array of detectors to have improved angular resolution to allow localisation of signal sources. Sect. 1 of this paper begins by reviewing proposals for the next ground based detectors,and presents an analysis of the sensitivity of an 8 km armlength detector, which is proposed as a safe and cost-effective means to attain a 4-fold improvement in sensitivity. The scientific benefits of creating a pair of such detectors in China and Australia is emphasised. Sect. 2 of this paper discusses the high performance suspension systems for test masses that will be an essential component for future detectors, while sect. 3 discusses solutions to the problem of Newtonian noise which arise from fluctuations in gravity gradient forces acting on test masses. Such gravitational perturbations cannot be shielded, and set limits to low frequency sensitivity unless measured and suppressed. Sects. 4 and 5 address critical operational technologies that will be ongoing issues in future detectors. Sect. 4 addresses the design of thermal compensation systems needed in all high optical power interferometers operating at room temperature. Parametric instability control is addressed in sect. 5. Only recently proven to occur in Advanced LIGO, parametric instability phenomenon brings both risks and opportunities for future detectors. The path to future enhancements of detectors will come from quantum measurement technologies. Sect. 6 focuses on the use of optomechanical devices for obtaining enhanced sensitivity, while sect. 7 reviews a range of quantum measurement options.
