共查询到20条相似文献,搜索用时 31 毫秒
1.
The gravitational and electromagnetic radiation from chiral superconducting cosmic string loops is calculated. The formulas for energy, momentum, and angular momentum losses due to gravitational and electromagnetic radiation from chiral loops of an arbitrary configuration are derived. After summation over all modes, expressions for the corresponding radiation rates averaged over the loop oscillation period have the form of four-dimensional integrals. These formulas are reduced to sums over the kinks for loops composed of piece-wise linear strings. For three examples of string loops, the total radiation rates are calculated numerically depending on the chiral current along the string. In the limit of a nearly maximum current, which corresponds to a stationary loop (vorton) configuration, we determine the upper bounds on the gravitational and electromagnetic radiation. We also estimate the oscillation damping time of a nearly stationary loop. 相似文献
2.
As a typical example of the sound radiation caused by the oscillation of a large sized structure, the infrasound radiation from a highway bridge is theoretically analyzed by applying a lifting surface technique. The relation between the bridge oscillation and the corresponding infrasound radiation is made clear quantitatively. By using measured results of the bridge oscillation due to the passage of a vehicle, the infrasound radiated from the bridge is estimated analytically. The results are compared with the measurements, and good agreement is seen. Moreover, it is shown that the reflection of sound at the ground causes both the radiation impedance of the bridge and the radiation pattern of the sound pressure to vary considerably according to the height of the bridge from the ground. Hence the height of the bridge is an important factor which controls sound pressure level (SPL) near the ground, on which the noise is actually perceived. 相似文献
3.
Tunable narrow linewidth radiation by optical parametric oscillation has many applications, particularly in spectroscopic
investigation. In this paper, different techniques such as injection seeding, use of spectral selecting element like grating,
grating and etalon in combination, grazing angle of incidence, entangled cavity configuration and type-II phase matching have
been discussed for generating tunable narrow linewidth radiation by singly resonant optical parametric oscillation process. 相似文献
4.
The theoretical work of Braginsky predicted that radiation pressure can couple the mechanical, mirror eigenmodes of a Fabry-Pérot resonator to its optical modes, leading to a parametric oscillation instability. This regime is characterized by regenerative mechanical oscillation of the mechanical mirror eigenmodes. We have recently observed the excitation of mechanical modes in an ultrahigh Q optical microcavity. Here, we present a detailed experimental analysis of this effect and demonstrate that radiation pressure is the excitation mechanism of the observed mechanical oscillations. 相似文献
5.
V. A. Averchenko T. Yu. Golubeva Yu. M. Golubev C. Fabre 《Optics and Spectroscopy》2008,105(5):758-770
Information applications of the essentially multimode (in time) radiation of a degenerate optical parametric oscillator operating above the oscillation threshold, such as protocols of quantum parallel dense coding and multimode quantum teleportation, have been considered. The stream of Shannon mutual information as a function of the spectral width of Alice’s signal and the spectral fidelity of transmission of a multimode quantum signal are evaluated from the estimates of the achievable radiation squeezing that occurs as the oscillation threshold is approached. The advantages of the multimode scheme over the single-mode scheme are discussed. 相似文献
6.
We report the results of computer simulation of the emission of radiation by an extended two-level medium in a ring cavity. The cases of using strong external monochromatic, quasi-monochromatic, and biharmonic radiation for pumping the two-level medium are analyzed. It is shown that the emission of radiation with spectral content different from that of the pump radiation, which is interpreted as the inversionless oscillation, is the result of the spatiotemporal dynamics of light propagation in an extended two-level medium imbedded in a cavity. The appearance of this radiation is not related to known resonances of amplification of a weak probe field in a thin layer of the two-level system (the effect of inversionless oscillation) induced by strong resonance monochromatic or biharmonic field, as was thought before. 相似文献
7.
Based on the Floquet theory and Keldysh's nonequilibrium Green's function methods, we study the electron transport through the HgTe/CdTe quantum wells (QWs) irradiated by a monochromatic laser field. We find that when the laser field is applied, the edge states are split into a series of sidebands. When the Fermi level lies among these sidebands, the quantized plateau of the conductance is destroyed. Instead, the conductance versus the radiation frequency exhibits the successive oscillation peaks corresponding to the resonant tunneling through the sidebands of the edge states. The resonant interaction between the quasiparticles and the radiation field opens the gaps in the crossing region of the sidebands, which can be tuned by the radiation strength and frequency. This leads to the shift of the oscillation peaks in the conductance. We also show that the amplitudes of the oscillation peaks in the conductance are governed by the radiation strength and frequency. 相似文献
8.
L.-C. Tung C.L. Yang D. Smirnov L.N. Pfeiffer K.W. West R.R. Du Y.-J. Wang 《Solid State Communications》2009,149(37-38):1531-1534
Submillimeter wave induced resistance oscillations in two ultra-high mobility GaAs/Al0.24Ga0.76As quantum well samples have been investigated by means of a backward wave oscillator and far-infrared laser at 3He temperatures. Subnikov–de Haas oscillation, submillimeter wave induced resistance oscillation, and magnetoplasmon resonance occur simultaneously in this frequency regime. The primary radiation induced resistance minimum shifts toward cyclotron resonance with increasing radiation frequency. The positions of these minima agree well with those of the magnetoplasmon resonance. The higher-order harmonics of the resistance oscillation remain around the multiples of the cyclotron resonance frequency. An in situ transmission measurement exhibits an asymmetric broadening of the cyclotron resonance, appearing as a combination of the cyclotron resonance and the magnetoplasmon resonance, but no features directly linked to the microwave induced resistance oscillation can be seen. 相似文献
9.
Su-Yun Zhou 《Optik》2012,123(19):1707-1710
The electron dynamics and harmonics radiation spectra due to electron oscillation driven by laser standing wave (SW) have been investigated considering a single electron mode. It is found that electron can pass through or be reflected from laser SW as electron is shot into laser SW from antinodes plane with initial velocity parallel to electric field of SW, and for electron incidence at arbitrary plane the attraction plane of electron trajectories will transfer from nodes plane to antinodes plane if initial electron kinetic energy exceeds a critical value. Further, the harmonics emission due to electron oscillation during passing through laser SW is considered in two cases of electron incidence plane at nodes and antinodes. In case of electron incidence at nodes, the spectrum of radiation is redshifted for backward radiation and blueshifted for forward radiation, and broadening of spectrum is noticed. These effects are much more pronounced at higher laser intensities. However, for case with electron incidence at antinodes, these phenomena vanish. 相似文献
10.
Studies on the properties of flow-induced oscillation and sound radiation in streamlined protuberant special cavities 总被引:1,自引:0,他引:1
I.IntroductionAsanuidpassingthroughthecavityatcertainflowrate,themediuminthemouthandthccavityisoscillatingandsoundisradiated.Noton1ystochasticturbu1encenoiscispossi-blyproducedbutsinglefrequencysoundofspecia1lydesignatedpitchisalsoproduced.Andthusthespcctrumofthcradiatedsoundisshownascontinuousspectrumandcharacteristiclinespcctrum.Inthiscascwcmaycallitflow-inducedosci1lation.Flow-inducedoscillationandsoundradiationcanbeproducedasafluid(waterorgas)passingthroughthecavitybysinkingcavityunderint… 相似文献
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Self-optical parametric oscillation is demonstrated for the first time to our knowledge in a periodically poled neodymium-doped lithium niobate (Nd:PPLN) crystal. The crystal is pumped by a cw Ti:sapphire laser at 813.5 nm. The Nd(3+) ions absorb the 813.5-nm radiation to generate 1084-nm laser oscillation. The internally Q switched 1084-nm radiation pumps the periodically poled lithium niobate host matrix to generate optical parametric oscillation at 1.55 and 3.6 microm . Up to 24% conversion efficiency from laser to signal is observed. 相似文献
13.
In a planar undulator employed free electron laser (FEL), each harmonic radiation starts from linear amplification and ends with nonlinear harmonic interactions of the lower nonlinear harmonics and the fundamental radiation. In this paper, we investigate the harmonic generation based on the dispersion relation driven from the coupled Maxwell-Vlasov equations, taking into account the effects due to energy spread, emittance, betatron oscillation of electron beam as well as diffraction guiding of the radiation field. A 3D universal scaling function for gain of the linear harmonic generation and a 1D universal scaling function for gain of the nonlinear harmonic generation are presented, which promise rapid computation in FEL design and optimization. The analytical approaches have been validated by 3D simulation results in large range. 相似文献
14.
In a planar undulator employed free electron laser(FEL),each harmonic radiation starts from linear amplification and ends with nonlinear harmonic interactions of the lower nonlinear harmonics and the fundamental radiation.In this paper,we investigate the harmonic generation based on the dispersion relation driven from the coupled Maxwell-Vlasov equations,taking into account the effects due to energy spread,emittance,betatron oscillation of electron beam as well as diffraction guiding of the radiation field.A 3D universal scaling function for gain of the linear harmonic generation and a 1D universal scaling function for gain of the nonlinear harmonic generation are presented,which promise rapid computation in FEL design and optimization.The analytical approaches have been validated by 3D simulation results in large range. 相似文献
15.
首次报道了由金原子发出的波长627.8nm的放大自发辐射脉冲具有弛豫振荡.得出其在时间域和频率域的规律.这种振荡可能是高增益脉冲辐射系统的一种普遍现象. 相似文献
16.
Schnell M Sävert A Landgraf B Reuter M Nicolai M Jäckel O Peth C Thiele T Jansen O Pukhov A Willi O Kaluza MC Spielmann C 《Physical review letters》2012,108(7):075001
We investigate the properties of a laser-plasma electron accelerator as a bright source of keV x-ray radiation. During the interaction, the electrons undergo betatron oscillations and from the carefully measured x-ray spectrum the oscillation amplitude of the electrons can be deduced which decreases with increasing electron energies. From the oscillation amplitude and the independently measured x-ray source size of (1.8±0.3) μm we are able to estimate the electron bunch diameter to be (1.6±0.3) μm. 相似文献
17.
An inversionless gain of anti-Stokes radiation above the oscillation threshold in an optically dense far-from-degenerate double- ? Doppler-broadened medium accompanied by Stokes gain is predicted. The outcomes are illustrated with numerical simulations applied to sodium dimer vapor. Optical switching from absorption to gain via transparency controlled by a small variation of the medium and of the driving radiation parameters, which are at a level of less than one photon per molecule, is shown. 相似文献
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Zhao P Ragam S Ding YJ Zotova IB Mu X Lee HC Meissner SK Meissner H 《Optics letters》2012,37(7):1283-1285
We implemented a singly resonant optical parametric oscillator based on adhesive-free-bonded periodically inverted KTiOPO4 plates. It has major advantages such as walk-off compensation and oscillation at four wavelengths. The threshold of the oscillation was measured to be 8 MW/cm2, which is about a factor of 4 lower than that based in two separate KTiOPO4 crystals. By frequency-mixing the dual-wavelength output in GaP stacks, we generated the terahertz radiation at 2.54 THz. The tuning range of the terahertz output was demonstrated to be 2.19-2.77 THz. 相似文献