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81.
Michael E. Tobar Eugene N. Ivanov David G. Blair 《General Relativity and Gravitation》2000,32(9):1799-1821
It is shown that a large improvement in liquid helium and ultra-cryogenically cooled resonant-mass gravitational wave detectors can be achieved through improved parametric transducers using either low loss sapphire dielectric resonators or niobium re-entrant cavities. Performance is analysed in relation to the existing resonant bar antenna Niobe and to massive spherical detectors. Applied to Niobe, a millisecond burst sensitivity of order 10–20 can be achieved, corresponding to a spectral strain sensitivity of 2 × 10-22
Hz with a 50 Hz bandwidth. Applied to an ultra-cryogenic 117 tonne spherical detector made from CuAl, a spectral strain sensitivity of better than 2 ×10-23/
Hz with a bandwidth of order 100 Hz can be achieved, which is close to the quantum limit. This sensitivity is comparable to that of advanced interferometer detectors at this frequency. 相似文献
82.
JIAO Li-hua XU Li-mei HONG Hu 《中国电子科技》2007,5(1):53-57
With the required increased audio pressure of the parametric ultrasonic transducer array and the difficulty to theoretically analyse the complex ultrasonic structure in audio beam application, an computationally efficient model is desired to describe the characteristic of the parametric ultrasonic transducer array for the system design and optimization. By applying the symmetry boundary conditions at the mid-plane in the thickness direction, a finite element model based on the haft thickness simplification is presented to analyze the parametric circular transducer which is designed by gluing the poly Vinylidene fluoride film (PVDF). The validity of the proposed model is confn'med by a comparison of finite element analysis results with the theoretical value and experimental data, which show that they are making a good agreement with each other. 相似文献
83.
84.
Chenghou Tu Wengang Guo Yongnan Li Shuanggen Zhang Fuyun Lu 《Optics Communications》2007,280(2):448-452
Based on the nonlinear polarization rotation (NPR) technique and a fiber Mach–Zehnder interferometer (MZI), a fiber laser which can work in two different modes has been demonstrated. In one mode, it works as a continuous wave (CW) multiwavelength laser, and stable dual-, triple- and tetra-wavelength lasing with the wavelength spacing of 1.1 nm are obtained. In the other mode, it works as a passively mode-locked fiber laser, and the generated pulses have a repetition rate of 10.6 MHz, an FWHM width of 800 ps and the largest energy of 1 nJ. The multi-functional property makes this fiber laser a very convenient, cost effective and multi-purpose laser source. 相似文献
85.
In this report, we demonstrate the efficient generation of collinearly propagating photon pairs in a bulk periodically poled potassium titanyl phosphate pumped by a cw laser. The detected coincidence counts are more than 7400/s with 3.58 mW pump power in a Hanbury-Brown-Twiss-type experiment. The estimated photon pair production rate is about 0.73 MHz/mW. This is very promising for some applications, such as quantum key distribution, proof of the Bell-inequality, preparation of single photon states in broadband wave packets, Franson-type interference and so on. 相似文献
86.
Carole Diederichs David Taj Thimothe Lecomte Crisitiano Ciuti Philippe Roussignol Claude Delalande Aristide Lemaître Ludovic Largeau Olivia Mauguin Jacqueline Bloch Charles Leyder Alberto Bramati Elisabeth Giacobino Jrme Tignon 《Comptes Rendus Physique》2007,8(10):1198-1204
We report the realization of a monolithic vertical-cavity, surface emitting micro-optical parametric conversion nanostructure, triply resonant with the parametric frequencies, allowing parametric oscillation with ultra-low pump power threshold. The photonic phase-space naturally provides triple resonance for the parametric frequencies, together with built-in cavity phase-matching for the pump wave at normal incidence. Parametric oscillation is observed in both the strong and weak exciton–photon coupling regime, allowing a high operating temperature. Signal and idler beams can be collected at 0° or at finite angles. The OPO threshold is low enough to envisage the realization of an all-semiconductor electrically-pumped micro-parametric oscillator. To cite this article: C. Diederichs et al., C. R. Physique 8 (2007). 相似文献
87.
A. Porzio V. DAuria P.Aniello M.G.A. Paris S. Solimeno 《Optics and Lasers in Engineering》2007,45(4):463
We present a continuous variable quantum communication protocol based on bright continuous-wave twin-beams generated by a type-II OPO. Intensity correlation between the beams is used in conjunction with a binary randomization of polarization to guarantee security and reveal eavesdropping actions. The scheme presented is asymmetric. Bob (the receiver) retains one of the beams and sends the other one to Alice after a random rotation of its polarization. The cryptographic key elements are encoded through amplitude modulation by Alice, who sends back her beam to Bob after a second rotation of the polarization. Eventually, the beams are detected by Bob after a further random polarization rotation. The security of the system and the possibility of revealing the eavesdropping action in the case of an individual attack are demonstrated by evaluating the bit error rates. 相似文献
88.
In this paper the gain characteristics of two-pump fiber optical parametric amplifiers (FOPA) with two-section highly nonlinear fibers are analyzed numerically and the parameters of the fibers are optimized to reach broad and flat gain spectra using genetic algorithm. Different from the previous methods, here the space between two pump wavelengths and the parameter β4 of the fibers are included as a pivotal factor in the optimization. The numerical simulation shows that using two-section practical high nonlinear fibers, the amplifier may reach 110 nm bandwidth covering 1495–1605 nm with 10.5 dB average gain and gain ripple of 0.17 dB, when the total pump power is 1 W. 相似文献
89.
90.
Jibin Li 《Journal of Applied Analysis & Computation》2015,5(1):138-140
This paper considers a long wave-short wave model. It shows that under three different parameter conditions, this system has three types of exact explicit travelling wave solutions. Their parametric representations have been given. 相似文献