The characteristics of the energy transfer and nonlinear coupling among edge electromagnetic turbulence in thermal quench sub-period of the internal reconnection event (IRE) are studied at the sino-united spherical ...The characteristics of the energy transfer and nonlinear coupling among edge electromagnetic turbulence in thermal quench sub-period of the internal reconnection event (IRE) are studied at the sino-united spherical tokamak device using multiple Langmuir and magnetic probe arrays. The wavelet bispectral analysis and the modified Kim method are applied to investigate linear growth/damping and nonlinear energy transfer rates, along with multi-field turbulence interactions. The results show a multi-field nonlinear energy transfer from electrostatic to magnetic turbulence that results in two-mode coupling in magnetic turbulence, which may play a crucial role to trigger the IRE.展开更多
Based on solving the couple mode equation numerically, the characterization of the signal power on the gate power was analyzed. And the relationship of the tolerance of the grating period and the bulk temperature on t...Based on solving the couple mode equation numerically, the characterization of the signal power on the gate power was analyzed. And the relationship of the tolerance of the grating period and the bulk temperature on the interaction length was analyzed.展开更多
We report the single-to-multiple channel wavelength conversions of 1.57-ps pulses based on cascaded secondharmonic generation and difference frequency generation in quasi-phase-matched periodically poled lithium hieba...We report the single-to-multiple channel wavelength conversions of 1.57-ps pulses based on cascaded secondharmonic generation and difference frequency generation in quasi-phase-matched periodically poled lithium hiebate waveguides. For single-to-single channel wavelength conversion, no external cavity laser is required with use of a fibre ring laser. The conversion efficiency is about -21.44 dB. The converted idler wavelength can be tuned from 1526.4nm to 1537.5nm as the lasing pump wavelength is varied from 1566.1 nm to 1555.0nm. By employing several input pumps, tunable single-to-dual and single-to-triple channel wavelength conversions are experimentally demonstrated.展开更多
We report the transformation of a linear electro-optically tunable non-phase-matched second-order nonlinear process into a cascaded second-order nonlinear process in a bulk KTP crystal to generate the effect of electr...We report the transformation of a linear electro-optically tunable non-phase-matched second-order nonlinear process into a cascaded second-order nonlinear process in a bulk KTP crystal to generate the effect of electrooptically tunable Kerr-type nonlinearity. By applying an electric field on the x–y plane, parallel to the z-axis of the crystal, phase mismatch is created, which introduces a nonlinear phase shift between the launched and reconverted fundamental waves from the generated second harmonic wave. Due to the nonuniform radial intensity distribution of a Gaussian beam, a curvature will be introduced into the fundamental wavefront, which focuses or defocuses the incident beam while propagating through the crystal.展开更多
Dissipative solitons have been realized in mode-locked fiber lasers in the theoretical framework of the Ginzburg±Landau equation and have significantly improved the pulse energy and peak power levels of such lase...Dissipative solitons have been realized in mode-locked fiber lasers in the theoretical framework of the Ginzburg±Landau equation and have significantly improved the pulse energy and peak power levels of such lasers.It is interesting to explore whether dissipative solitons exist in optical parametric oscillators in the framework of three-wave coupling equations in order to substantially increase the performance of optical parametric oscillators.Here,we demonstrate a temporalfiltering dissipative soliton in a synchronously pumped optical parametric oscillator.The temporal-gain filtering of the pump pulse combined with strong cascading nonlinearity and dispersion in the optical parametric oscillator enables the generation of a broad spectrum with a nearly linear chirp;consequently,a significantly compressed pulse and high peak power can be realized after dechirping outside the cavity.Furthermore,we realized,for the first time,dissipative solitons in an optical system with a negative nonlinear phase shift and anomalous dispersion,extending the parameter region of dissipative solitons.The findings may open a new research block for dissipative solitons and provide new opportunities for mid-infrared ultrafast science.展开更多
Flute mode turbulence plays an important role in numerous applications,such as tokamak,Z-pinch,space and astrophysical plasmas.In a low beta plasma flute oscillations are electrostatic and in the nonlinear stage they ...Flute mode turbulence plays an important role in numerous applications,such as tokamak,Z-pinch,space and astrophysical plasmas.In a low beta plasma flute oscillations are electrostatic and in the nonlinear stage they produce large scale density structures co-mingling with short scale oscillations.Large scale structures are responsible for the enhanced transport across the magnetic field and appearance of short scales leads to ion heating,associated with the ion viscosity.In the present paper nonlinear equations which describe the nonlinear evolution of the flute modes treated as compressible electromagnetic oscillations in a finite beta inhomogeneous plasma with nonuniform magnetic field are derived and solved numerically.For this purpose the 2D numerical code FLUTE was developed.Numerical results show that even in a finite beta plasma flute mode instability can develop along with formation of large scale structures co-existing with short scale perturbations in the nonlinear stage.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11261140327,11325524,11475102 and11575057the Chinese National Fusion Project for ITER under Grant Nos 2013GB112001,2013GB107001 and 2014GB108000+1 种基金the Tsinghua University Initiative Scientific Research Programthe 221 Program
文摘The characteristics of the energy transfer and nonlinear coupling among edge electromagnetic turbulence in thermal quench sub-period of the internal reconnection event (IRE) are studied at the sino-united spherical tokamak device using multiple Langmuir and magnetic probe arrays. The wavelet bispectral analysis and the modified Kim method are applied to investigate linear growth/damping and nonlinear energy transfer rates, along with multi-field turbulence interactions. The results show a multi-field nonlinear energy transfer from electrostatic to magnetic turbulence that results in two-mode coupling in magnetic turbulence, which may play a crucial role to trigger the IRE.
文摘Based on solving the couple mode equation numerically, the characterization of the signal power on the gate power was analyzed. And the relationship of the tolerance of the grating period and the bulk temperature on the interaction length was analyzed.
基金Supported by the National Natural Science Foundation of China under Grant No 60577006.
文摘We report the single-to-multiple channel wavelength conversions of 1.57-ps pulses based on cascaded secondharmonic generation and difference frequency generation in quasi-phase-matched periodically poled lithium hiebate waveguides. For single-to-single channel wavelength conversion, no external cavity laser is required with use of a fibre ring laser. The conversion efficiency is about -21.44 dB. The converted idler wavelength can be tuned from 1526.4nm to 1537.5nm as the lasing pump wavelength is varied from 1566.1 nm to 1555.0nm. By employing several input pumps, tunable single-to-dual and single-to-triple channel wavelength conversions are experimentally demonstrated.
文摘We report the transformation of a linear electro-optically tunable non-phase-matched second-order nonlinear process into a cascaded second-order nonlinear process in a bulk KTP crystal to generate the effect of electrooptically tunable Kerr-type nonlinearity. By applying an electric field on the x–y plane, parallel to the z-axis of the crystal, phase mismatch is created, which introduces a nonlinear phase shift between the launched and reconverted fundamental waves from the generated second harmonic wave. Due to the nonuniform radial intensity distribution of a Gaussian beam, a curvature will be introduced into the fundamental wavefront, which focuses or defocuses the incident beam while propagating through the crystal.
基金the National Natural Science Foundation of China(Nos.61675130,62075126 and 91850203)。
文摘Dissipative solitons have been realized in mode-locked fiber lasers in the theoretical framework of the Ginzburg±Landau equation and have significantly improved the pulse energy and peak power levels of such lasers.It is interesting to explore whether dissipative solitons exist in optical parametric oscillators in the framework of three-wave coupling equations in order to substantially increase the performance of optical parametric oscillators.Here,we demonstrate a temporalfiltering dissipative soliton in a synchronously pumped optical parametric oscillator.The temporal-gain filtering of the pump pulse combined with strong cascading nonlinearity and dispersion in the optical parametric oscillator enables the generation of a broad spectrum with a nearly linear chirp;consequently,a significantly compressed pulse and high peak power can be realized after dechirping outside the cavity.Furthermore,we realized,for the first time,dissipative solitons in an optical system with a negative nonlinear phase shift and anomalous dispersion,extending the parameter region of dissipative solitons.The findings may open a new research block for dissipative solitons and provide new opportunities for mid-infrared ultrafast science.
基金This work was supported by the United States Department of Energy under the follow-ing grants:Grant No.DE-FC52-01NV14050 at the University of Nevada at Reno,Grant No.DE-AC04-94AL85000 at Sandia National LaboratoriesSandia is amultiprogramlab-oratory operated by Sandia Corporation,a Lockheed Martin Company,for the U.S.DOE under Contract DE-AC04-94AL85000.
文摘Flute mode turbulence plays an important role in numerous applications,such as tokamak,Z-pinch,space and astrophysical plasmas.In a low beta plasma flute oscillations are electrostatic and in the nonlinear stage they produce large scale density structures co-mingling with short scale oscillations.Large scale structures are responsible for the enhanced transport across the magnetic field and appearance of short scales leads to ion heating,associated with the ion viscosity.In the present paper nonlinear equations which describe the nonlinear evolution of the flute modes treated as compressible electromagnetic oscillations in a finite beta inhomogeneous plasma with nonuniform magnetic field are derived and solved numerically.For this purpose the 2D numerical code FLUTE was developed.Numerical results show that even in a finite beta plasma flute mode instability can develop along with formation of large scale structures co-existing with short scale perturbations in the nonlinear stage.