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Numerical investigation and potential tunability scheme on e^+e^- and π^+π^- stimulated pair creation from vacuum using high intensity laser beams

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High Power Laser Science and Engineering 2016年第4期4卷 1-7页

作者： I.Ploumistakis S.D.Moustaizis I.Tsohantjis Technical University of Crete Laboratory of Matter Structure and Laser Physics National and Kapodistrian University of Athens Faculty of PhysicsDepartment of Nuclear and Particle Physics

Numerical estimates for electrons and mesons particle–antiparticle creation from vacuum in the presence of strong electromagnetic fields are derived, using the complete probability density relation of Popov's imaginary time method(Popov, JETP Lett. 13, 185(1971); Sov. Phys. JETP 34, 709(1972); Sov. Phys. JETP 35, 659(1972); Popov and Marinov, Sov. J. Nucl. Phys. 16, 449(1973); JETP Lett. 18, 255(1974); Sov. J. Nucl. Phys. 19, 584(1974));(Popov,Phys. Let. A 298, 83(2002)), and within the framework of an experimental setup like the E144(Burke et al., Phys. ***. 79, 1626(1997)). The existence of crossing point among pair creation efficiency curves of different photon energies and the role of odd/even multiphoton orders in the production rates are discussed. Finally a kind of tunability process between the two creation processes is discussed.

关键词： high intensity lasers multiphoton processes pair production

Quantitative deviation of the two-photon absorption coefficient based on three laser pulse models

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Chinese Optics Letters 2010年第1期8卷 93-98页

作者：赵培德张勇包文霞张忠亚汪大云刘铭张志东 School of Science Hebei University of Technology

The pulse profile influence of excitation light on the two-photon absorption coefficient β is theoretically and numerically studied. Based on Gaussian spatial and temporal laser, we obtain an expansion formula of energy transmission. As compared with a plain beam and a pulse beam that is rectangular in time but Gaussian in space, the relative deviations of β turn out to be about 214% and 47%, respectively. These differences indicate that a smaller β may be obtained than the real one in usual nonlinear transmission. Our result suggests that by taking real pulse profile into account, a more exact β can be derived in energy transmission measurement.

关键词： Absorption Gaussian beams Light absorption Luminescence of organic solids multiphoton processes Optical materials Photons

Ground state cooling of an optomechanical resonator with double quantum interference processes

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Chinese Physics B 2021年第2期30卷 268-275页

作者： Shuo Zhang Tan Li Qian-Hen Duan Jian-Qi Zhang Wan-Su Bao Henan Key Laboratory of Quantum Information and Cryptography SSF IEUZhengzhouHenan 450001China Innovation Academy for Precision Measurement Science and Technology Wuhan 430071China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China

We present a cooling scheme with a tripod configuration atomic ensemble trapped in an optomechanical *** the employment of two different quantum interference processes,our scheme illustrates that it is possible to cool a resonator to its ground state in the strong cavity-atom coupling ***,with the assistance of one additional energy level,our scheme takes a larger cooling rate to realize the ground state *** addition,this scheme is a feasible candidate for experimental applications.

关键词： laser cooling coherent optical effects multiphoton processes optomechanics

Monte Carlo simulation of photon migration path in turbid media

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Chinese Optics Letters 2008年第7期6卷 530-532页

作者：王建岗王桂英徐至展 State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800

A new method of Monte Carlo simulation is developed to simulate the photon migration path in a scattering medium after an ultrashort-pulse laser beam comes into the medium. The most probable trajectory of photons at an instant can be obtained with this method. How the photon migration paths are affected by the optical parameters of the scattering medium is analyzed. It is also concluded that the absorption coefficient has no effect on the most probable trajectory of photons.

关键词： Absorption Monte Carlo methods multiphoton processes Pulsed laser applications Scattering Trajectories Turbidity

Theoretical analysis on two-photon absorption spectroscopy in a confined four-level atomic system

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Chinese Optics Letters 2009年第7期7卷 640-642页

作者：李院院白晋涛李莉张彦鹏侯洵 Institute of Photonics and Photonic Technology Key Laboratory of Photoelectronic Technology of Sha~nxi Province Northwest University Xi'an 710069 China Department of Physics Xi'an University of Arts and Science Xi'an 710065 China Key Laboratory for Physical Electronics and Devices of the Ministry of Education Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Transient Optics and Technology Xi'an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Xi'an 710068 China

We investigate theoretically two-photon absorption spectroscopy modified by a control field in a confined Y-type four-level system. Dicke-narrowing effect occurs both in two-photon absorption lines and the dips of transparency against two-photon absorption due to enhanced contribution of slow atoms. We also find that the suppression and the enhancement of two-photon absorption can be modified by changing the strength of the control field and the detuning of three laser fields. This control of two-photon absorption may have some applications in information processing and optical devices.

关键词： Absorption Atomic spectroscopy Data processing Light absorption Luminescence of organic solids multiphoton processes Optical instruments Optical materials Photons

Theoretical analysis on the efficiency of optical-optical double-color double-resonance multiphoton ionization

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Chinese Optics Letters 2009年第11期7卷 971-974页

作者：张贵银靳一东 School of Mathematics and Physics North China Electric Power University

Analytic formula of the efficiency of optical-optical double-color double-resonance multi-photon ionization （OODR-MPI） is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the influence of characteristic of the pump and probe laser on the ionization efficiency of （1＋2＋1） OODR-MPI process is simulated theoretically. It is shown that the pump laser will affect the ionization efficiency by the number control of the molecules excited to the first resonance state. The ionization efficiency is decided by the probe laser directly. Both of the excited molecules and ionization efficiency increase with the intensity and pulse duration of the laser until saturation. It is also found that the longer the delay time of the probe laser to the pump one is, the lower the ionization efficiency would be. The delay time ought to be smaller than the lifetime of the excited molecule in the practical use of the OODR-MPI technique.

关键词： Molecules multiphoton processes Particle detectors Photons Probes Pulsed laser applications Pumping (laser) Pumps Resonance

New phenomena in laser-assisted scattering of an electron by a muon

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Frontiers of physics 2018年第4期13卷 251-258页

作者： Wen-Yuan Du Peng-Fei Zhang Bing-Hong Wang Department of Modern Physics University of Science and Technology of China Hefei 230026 China

The scattering of an electron by a muon in the presence of a linearly polarized laser field is investigated in the first Born approximation. The theoretical results reveal the following： i） At medium and large scattering angles, many multiphoton processes occur during scattering, and these nonlinear phenomena may predict the resonant state of the electron and the muon formed in the collision process, ii） The photoabsorption （inverse brerasstrahlung） dominates the photoemission （bremsstrahlung）, causing the cross section to increase, iii） When the laser polarization deviates from the incident direction, the laser- modified total cross section depends considerably on the azimuthal angle of the scattered electron. The dependence of the cross section on the field strength, polarization direction, and electron-impact energy are studied.

关键词： laser-assisted scattering multiphoton processes nonlinear effect generalized Bessel function

Non-classical correlation between a single photon and the collective spin excited state of a cold atomic ensemble

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Chinese Optics Letters 2009年第11期7卷 1048-1050页

作者：陆小松陈群峰史保森郭光灿 Key Laboratory of Quantum Information University of Science and Technology of China

We experimentally establish a non-classical correlation between a single Stokes photon and the collective spin excited state of a cold atomic ensemble by using a spontaneous Raman scattering process. The correlation between them can be proved by transferring the spin excited state of the atomic ensemble into an anti-Stokes photon and checking the Cauchy-Schwarz inequality between the Stokes and the anti-Stokes photons. The non-classical correlation can be kept for at least 300 ns.

关键词： Atoms Excited states multiphoton processes Spin dynamics

Influence of laser intensity on the double-resonance multiphoton ionization process of NO molecule

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Chinese Optics Letters 2008年第11期6卷 800-803页

作者：张贵银靳一东 College of Mathematics and Physics North China Electric Power University.Baoding 071003

The analytic formula of the ionization efficiency in the process of double resonance enhanced multi-photon ionization （DREMPI） is derived from the dynamic rate equation about the interaction of photon and material. Based on this formula, the ionization efficiency and the laser power index versus laser intensity in the DREMPI process of NO molecule, via A2E and S2E intermediate resonant states, is numerically simulated. It is shown that the ionization efficiency of NO molecule increases with the laser intensity until getting saturation, while the laser power index decreases with the enhancement of the laser intensity and changes to zero at last. The variation of the laser power index with the laser intensity indicates that the ionization efficiency reaches saturation in the one, two, and three excitation steps respectively. It is also found that the narrower the laser pulse duration is, the higher becomes the laser intensity for saturation.

关键词： Ionization Ionization of liquids Lasers Molecules multiphoton processes Photoionization Photons Pulsed laser applications Pulsed laser deposition Resonance