共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Chénais S. Forget L. Philippet M.-C. Castex 《Applied physics. B, Lasers and optics》2007,89(2-3):223-229
The efficiency of a coherent vacuum ultraviolet (VUV) source at 125 nm, based on two-photon resonant four-wave mixing in mercury
vapor, has been enhanced by up to two orders of magnitude. This enhancement was obtained by locally heating a liquid mercury
surface with a pulsed excimer laser, resulting in a high-density vapor plume in which the nonlinear interaction occurred.
Energies up to 5 μJ (1 kW peak power) have been achieved while keeping the overall mercury cell at room temperature, avoiding
the use of a complex heat pipe. We have observed a strong saturation of the VUV yield when peak power densities of the fundamental
beams exceeded the GW/cm2 range, as well as a large intensity-dependent broadening (up to ∼ 30 cm-1) of the two-photon resonance. The source has potential applications for high-resolution interference lithography and photochemistry.
PACS 42.65.Ky; 52.38.Mf 相似文献
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Hollow-core photonic-crystal fibers are shown to substantially enhance four-wave mixing (FWM) of laser pulses in a gas filling the fiber core. Picosecond pulses of Nd:YAG fundamental radiation and its second harmonic are used to generate a signal at the frequency of the third harmonic by the FWM process 3omega = 2omega + 2omega - omega. The efficiency achieved for this process in a 9-cm-long, 13-microm-hollow-core-diameter photonic-crystal fiber, designed to simultaneously transmit a two-color pump and the FWM signal, is shown to be approximately 800 times higher than the maximum FWM efficiency attainable with the same laser pulses in the tight-focusing regime. 相似文献
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Coherent population transfer in an atom using a sequence of adiabatic rapid passages through single-photon resonances is well-known, but it requires that the frequency sweep match the changing frequencies of the atomic transitions. The same population transfer can be effected via a single multiphoton adiabatic rapid passage, which requires only a small frequency sweep, if it is possible to select the desired multiphoton transition from the many possible transitions. Here we report the observation of population transfer between Rydberg states by high order multiphoton adiabatic rapid passage. 相似文献
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《Physics letters. A》2006,359(5):366-372
We propose a robust scheme to generate single-photon Fock states and atom–photon and atom–atom entanglement in atom–cavity systems. We also present a scheme for quantum networking between two cavity nodes using an atomic channel. The mechanism is based on Stark-chirped rapid adiabatic passage (SCRAP) and half-SCRAP processes in a microwave cavity. The engineering of these states depends on the design of the adiabatic dynamics through the static and dynamic Stark shifts. 相似文献
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Weicheng Chen Wencheng Xu Zhanqiang Liang Aiping Luo Hu Cui Dingan Han Libing Chen Hong Lu 《Optics & Laser Technology》2007,39(4):696-700
We propose a new method to strengthen the nonlinear pulses robustness to polarization mode dispersion through modulating the breath oscillation behavior of two principal polarization components of optical pulses. The optical realization of the breath behavior modulation is based on the degenerate four-wave mixing effect in fibers with high birefringence. The breath intensity increases and the periodical breath oscillation distances shorten in the process of breath behavior modulation. It is proved that the breath-modulated pulses have stronger adaptive abilities to polarization mode dispersion than common solitons when propagating in conventional single-mode fibers with random birefringence. 相似文献
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Two-qutrit maximally entangled states prepared via adiabatic passage in ion-trapped system 下载免费PDF全文
This paper considers a scheme for the preparation of two-qutrit entangled states via adiabatic passage in iontrapped system.In the proposal,the two three-level V-type ions are initially cooled to the ground states and need not be separately addressed.Moreover,only the ionic states act as memory and the system evolves in the dark space during the whole procedure,which makes the system robust against the decoherence and the fluctuation of the laser pulse. 相似文献
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V.S. Malinovsky J.L. Krause 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(2):147-155
We present a general theory of adiabatic rapid passage (ARP) with intense, linearly chirped laser pulses. For pulses with
a Gaussian profile and a fixed bandwidth, we derive a rigorous formula for the maximum temporal chirp rate that can be sustained
by the pulse. A modified Landau-Zener formula displays clearly the relationships among the pulse parameters. This formula
is used to derive the optimal conditions for efficient, robust population transfer. As illustrations of the theory, we present
results for two- and four-level systems, and selective vibronic excitation in the I2 molecule. We demonstrate that population transfer with chirped pulses is more robust and more selective than population transfer
with transform-limited pulses.
Received 6 September 2000 and Received in final form 25 September 2000 相似文献
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We have achieved a four-wave mixing process in a high-finesse highly nonlinear fiber Fabry-Perot resonator, where the amplified signal and idler were enhanced in transmission by 6 dB and 10 dB respectively comparing with those in a single fiber. We used a 6 m long low-loss Fabry-Perot resonator with two high-reflectivity fiber Bragg gratings written directly into a highly nonlinear fiber provided by Sumitomo Electric Inc., where the minimised intracavity loss resulted in the finesse in excess of 100. The resonator length was locked for 30 min by means of a modified Pound-Drever-Hall technique. The maximum intracavity power was increased by 14.3 dB by increasing the stimulated Brillouin scattering threshold with periodic phase modulation by a pseudo-random bit sequence, with length matching that of the cavity. 相似文献
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We present the experimental demonstration of a novel, efficient, and selective technique to prepare population inversion. The technique is an extension of Stark-chirped rapid adiabatic passage (SCRAP), i.e., SCRAP among three states. In this process a Lambda-type quantum system is driven by two laser pulses, the pump and Stokes pulses, which are appropriately detuned from transition frequencies. A third laser pulse induces a dynamic Stark shift in the upper energy level, and the timing of all three pulses is controlled in order to prepare population inversion between the two lower states in the Lambda-type level scheme. Our data on population transfer in nitric oxide (NO) molecules clearly show that SCRAP among three states provides an advantageous alternative to such techniques as stimulated Raman adiabatic passage. 相似文献
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Coherent tunneling by adiabatic passage (CTAP) is a well-established technique for robust spatial transport of quantum particles in linear chains. Here we introduce two exactly-solvable models where the CTAP protocol can be extended to two-dimensional lattice geometries. Such bi-dimensional lattice models are synthesized from time-dependent second-quantization Hamiltonians, in which the bosonic field operators evolve adiabatically like in an ordinary three-level CTAP scheme thus ensuring adiabatic passage in Fock space. 相似文献
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We propose a novel technique for the creation of entangled pairs of two-state systems based upon adiabatic passage induced by a suitably crafted time-dependent external field. 相似文献
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Photon-pair generation by four-wave mixing in optical fibers 总被引:2,自引:0,他引:2
We present a theory to quantify a fundamental limit on correlated photon pairs generated through four-wave mixing inside optical fibers in the presence of spontaneous Raman scattering (SpRS). Our theory is able to explain current experimental data. We show that if correlated photon pairs are generated with polarization orthogonal to the pump the effect of SpRS is significantly reduced over a broad spectral region extending from 5 to 15 THz. 相似文献
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We demonstrate a new velocimetry technique for gas flows based on Nearly Degenerate Four-Wave Mixing (NDFWM). Measurements were performed on nitric oxide in a free-jet expansion using helium and argon as carrier gases, at flow velocities on the order of 1000 m/s. We obtained velocities by analyzing experimental spectra from the jet using a perturbative treatment of NDFWM that we extended to include an arbitrary bulk velocity. The results agreed with independent velocity measurements based on Laser-Induced Fluorescence (LIF), as well as with theoretical flow-field velocities, to better than 5% in all cases studied. 相似文献
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We investigate a life time broadened and coherently prepared five-state system for multi-wave mixing processes. We show that very efficient wave mixing occurs, producing an unconventional mixing wave that has the characteristics of both conventional four-wave mixing (FWM) and stimulated hyper-Raman (SHR) emission. In addition, we show interesting multiple simultaneous multi-photon interference effects at large propagation distances and demonstrate more than 10 orders of magnitude suppression of populations of the probe wave terminal state and the near three-photon resonance mixing wave generating state. These new type of multi-photon interference based induced transparency effects, which are critically dependent on two distinctive relaxation processes involving both an external supplied and an internally generated fields, are fundamentally different from the conventional three-state electromagnetically induced transparency effect which does not depend on propagation. As a consequence, both the probe and the wave-mixing field to propagate nearly free of absorption and distortions in a highly dispersive medium. 相似文献
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We have demonstrated electromagnetically induced transparency (EIT) in an inhomogeneously broadened spectral hole-burning system of Pr(3+)-doped Y(2)SiO(5) at 6 K. We have also shown enhancement of four-wave mixing under conditions of reduced absorption. This demonstration opens the possibilities of pursuing EIT applications such as high-resolution optical image processing and optical data storage in solids. 相似文献
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We propose a novel terahertz-wave source through the four-wave mixing effect in a conventional single-mode optical fiber pumped by a dual-wavelength laser whose difference frequency lies in the terahertz range. Surface-emitted geometry is employed to decrease absorption loss. A detailed derivation of the terahertz-wave power expression is presented using the coupled-wave theory. This is a promising way for realizing a reasonable narrow-band terahertz-wave source. 相似文献