共查询到20条相似文献,搜索用时 15 毫秒
1.
Twin beams generated by OPOs show quantum noise reduction. For type I crystals they reduce in the degenerate case to a single mode, which below threshold exhibits some degree of squeezing. In the nondegenerate case squeezing occurs in the spectrum of their intensity difference. After a theoretical analysis of their spectral properties in both non- and degenerate cases, measured intensity noise correlation and single beam spectra are discussed for pump powers up to 14 times the threshold value. 相似文献
2.
We show that radiation generated in optical parametric down-conversion with losses and noise is entangled for all times if the coupling coefficient is higher than half of damping constant and the product of damping constant and mean number of noise photons. For the process stimulated by means of chaotic light there is a saturable bound of its intensity for the generation of nonclassical light. Otherwise the quantum behaviour and entanglement are fully reduced. Under some restrictions for noise nonclassical light can also be generated at and below the threshold. 相似文献
3.
Three-colour continuous-variable (CV) entanglement can be directly generated by an injection-seeded nondegenerate optical parametric oscillator (INOPO). The quantum correlations among the pump, signal, and idler beams are calculated and discussed by applying sufficient inseparability criteria for CV entanglement. The results clearly show that strong three-colour CV entanglement can be produced by operating the pump above the oscillation threshold. The INOPO is easier to realize experimentally and more steady in comparison to that without an injected signal since the injected signal can increase the nonlinear conversion efficiency and the stability, as well as allow a large degree of tunability. This scheme can be very useful for the applications in quantum communication and computation networks. 相似文献
4.
A theoretical treatment is presented for a novel from of optical vortex state, in a microcavity optical parametric oscillator (OPO). The state comprises a vortex/anti-vortex pair in the signal and idler beams, with a Gaussian pump. A numerical solution of the microcavity OPO equations shows that such a vortex can be stable. 相似文献
5.
Pierre Suret Marc Lefranc Dominique Derozier Jaouad Zemmouri Serge Bielawski 《Optics Communications》2001,200(1-6):369-379
We report on the observation of fast oscillations at frequencies of a few MHz in a triply resonant optical parametric oscillator. These oscillations can appear alone, or superimposed on slow oscillations due to thermo-optical instabilities, and display a great variety of waveforms. The analysis of the regimes observed experimentally leads us to conjecture that the mechanism responsible for this instability is not the Hopf bifurcation of the single-mode mean-field model, but that it is based on the interaction of two signal fields oscillating in cavity modes with neighboring frequencies. This interpretation is supported by numerical simulations of the mean-field model with two coupled modes, which reproduce well the behaviors observed experimentally. We also find chaotic solutions of this model, which unveils another possible scenario leading to deterministic chaos in this system. 相似文献
6.
In this paper, nonclassical light propagation through passive optical coupler is investigated. On the other hand, passive optical device design for nonclassical light is analyzed in this work. Effect of mode mismatching including mismatching in propagation constant on operation of the considered device is studied. We investigate different separable and entangled input excitations with single photons in this case. We specially study the measure of entanglement and effect of propagation constant mismatch on it. The simultaneous effect of loss and mismatch is also studied. Obtained results for different excitation states illustrate that there is a possibility to design such that the system operation can be immune versus fabrication imperfections. 相似文献
7.
Einstein——Podolsky——Rosen entanglement in time-dependent periodic pumping non-degenerate optical parametric amplifier 下载免费PDF全文
The solution of the time-dependent periodic pumping non-degenerate
optical parametric amplifier (NOPA) is derived when the pump
depletion is considered both above and below thresholds. Based on
this solution, the quantum fluctuation calculated shows that a high
entanglement and a good squeezing degree of the parametric light
beams are achieved near and above thresholds. We adopt two kinds of
pump fields: (i) a continuously modulated pump with a sinusoidal
envelope; (ii) a sequence of laser pulses with Gaussian envelopes.
We analyse the time evolution of continuous variable entanglement by
analytical and numerical calculations, and show that the periodic
driven pumping also improves the degree of entanglement. The
squeezing and Einstein-Podolsky-Rosen (EPR) entanglement by using
the two pumping driven functions are investigated from below to
above the threshold regions, the tendencies are nearly the same, and the
Gaussian driven function is superior to that of the sine driven function,
when the maximum squeezing and the minimum variance of
quantum fluctuation are considered. In the meantime, the
generalization of frequency degenerate OPA to frequency
non-degenerated OPA problem is investigated. 相似文献
8.
Character analysis of slow light with communication waveband in fiber optical parametric amplifier 总被引:1,自引:0,他引:1
The comprehensive characters of delay time and delay bandwidth with distortion, signal wavelength dependence and delay bandwidth product in fiber optical parametric amplifier are investigated theoretically when the pump locates at anomalous dispersion region. The delay character of single pulse, data stream with certain bit pattern and pseudo random data stream are analyzed comprehensively. In this category of fiber optical parametric amplifier, the delay time and delay bandwidth product vary from signal wavelengths and bit rates. For the same nonlinear coefficient, pump power and fiber length, the diverse dependences of bit pattern in different signal wavelengths are found by numerical simulation. The impacts of pump power and fiber length on the delay character and distortion are also discussed. These relations are conductive to the design of slow light based on fiber optical parametric amplifier in telecommunication waveband. 相似文献
9.
S. Aliauskas R. Butkus A. Piskarskas K. Regelskis V. Smilgevi
ius 《Optics Communications》2007,280(2):463-467
We report on theoretical and experimental investigations of two crystal traveling-wave optical parametric generator (OPG). It is shown that the efficiency and angular structure of traveling-wave tunable OPG output depends on the distance between the two crystals. Air dispersion driven efficiency modulation at different OPG output wavelengths is observed experimentally and confirmed by theoretical calculations. 相似文献
10.
N. H. Adamyan G. Yu. Kryuchkyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2008,43(2):58-62
The time-domain properties of Einstein-Podolsky-Rosen (EPR) entangled states of light are studied by means of analysis of both the Wigner functions and variance of quadrature amplitudes of generated modes. As a source of EPR states a non-degenerate optical parametric oscillator is considered driven by a sequence of laser pulses with a Gaussian time envelope. 相似文献
11.
Hongjun Liu Hongying Wang Xiaoli Li Yishan Wang Wei Zhao Chi Ruan 《Optics Communications》2009,282(9):1858-1860
Stacking chirped pulse optical parametric amplification based on a home-built Yb3+-doped mode-locked fiber laser and an all-fiber pulse stacker has been demonstrated. Energic 11 mJ shaped pulses with pulse duration of 2.3 ns and a net total gain of higher than 1.1 × 107 at fluctuation less than 2% rms are achieved by optical parametric amplification pumped by a Q-switched Nd:YAG frequency-doubled laser, which provides a simple and efficient amplification scheme for temporally shaped pulses by stacking chirped pulse. 相似文献
12.
X. L. Li H. J. Liu H. Y. Wang W. Zhao Y. S. Wang S. X. Shi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(2):309-312
A novel double-pass noncollinear optical parametric chirped pulse amplifier
based on an Yb3+-doped passively mode-locked fiber laser has been
demonstrated in this paper. The signal was double-pass amplified in a single
nonlinear crystal by a long pump pulse, and the signal and pump pulses of
each pass were completely phase matched in the plane of the maximum
effective nonlinearity. Net saturated gain of 2×106 was
achieved and the superfluorescence was suppressed by increasing the overlap
time between the signal and pump pulses. 相似文献
13.
Based on the coupled wave equations, optical chirped-pulse parametric amplification (OPCPA) is simulated and its characteristics are investigated under the conditions of small-signal and pump depletion. The influence of the group-velocity mismatch and the phase mismatch among the three waves on the process of the amplification are discussed, respectively. Compared with the conventional chirped-pulse amplification system, synchronization between pump and signal-pulses is a crucial issue in OPCPA. The requirement on Δτp–s as well as the stability of the system is investigated. 相似文献
14.
Baigang Zhang Jianquan Yao Tieli Zhang Feng Ji Yang Lu Pu Zhao 《Optics Communications》2007,270(2):368-372
A simple way to realize a fast tunable quasi-phase-matched optical parametric generation without crystal rotation, temperature changing or multi-grating periodically poled crystal translation is presented. The key is to translate a segmented crystal which is stacked by a lithium niobate crystal with three teeth and a single grating periodically poled crystal. The signal wavelength is tunable near 1.55 μm with the signal power of 90 mW. 相似文献
15.
Temperature-tunable nanosecond optical parametric oscillator based on periodically poled 总被引:1,自引:0,他引:1
We report a compact quasi-phase-matched optical parametric oscillator (OPO) using periodically poled MgO-doped LiNbO3 with different grating periods. The OPO is pumped by a diode-pumped passively Q-switched Nd:YAG laser providing 4.8-ns pulses at 5.4-kHz repetition rate. The OPO generates signal and idler wavelengths tunable in the ranges of 1.5– and 2.8–, respectively, by changing the crystal temperature between room temperature and . The temperature-dependent Sellmeier equation for the extraordinary refractive index of MgO-doped LiNbO3 is modified in the Mid-IR region, which gives an accurate prediction of the experimental temperature-tuning results. The linewidth of the signal wave is in the range of 0.5–1.0 nm without any controlling element. 相似文献
16.
17.
Xinjie Lv Zhan Sui Zhida Gao Mingzhong Li Qinghua Deng Shi-ning Zhu 《Optics & Laser Technology》2008,40(1):21-29
We report a theoretical analysis and numerical simulation of bandwidth and stability enhancement in optical parametric amplification (OPA) when using chirped periodically poled KTiOPO4. Calculation results show that the bandwidth and stability are enhanced significantly by the use of a chirped grating. Temperature-gradient and fanned gratings are introduced and chirp factors of them are deduced and calculated. The use of a fanned grating flattens the Quasi-phase-matching response and improves the efficiency. Finally, we propose a method to reduce the instability induced by an unstable pump. 相似文献
18.
报道了一台高重复频率2 mm光学参量振荡器泵浦的磷锗锌光学参量振荡器。磷锗锌晶体(ZnGeP2,简称ZGP)采用Ⅰ类相位匹配方式,切割角度q为55°,f为0°,尺寸5.5 mm×6 mm×18 mm,在4.0 kHz重复频率下,当注入5.2 W的2 mm圆偏振光时,获得310 mW中红外输出,p偏振态2 mm到3~5 mm光-光转换效率12%。通过调节晶体的角度,实验获得ZGP光学参量振荡器的波长调谐曲线,在误差范围内与理论变化规律相符。 相似文献
19.
Shifeng Du Dongxiang Zhang Yuxian Shi Qinan Li Baohua Feng Jing-yuan Zhang 《Optics Communications》2008,281(19):5014-5018
We report the characteristics of the amplified stimulated Raman scattering (SRS) pulses generated in liquid benzene by a picosecond (ps) β-barium borate (BBO) optical parametric amplifier (OPA). When the OPA system was used as an energy amplifier for SRS pulses, with a pump energy of 2.4 mJ at 355 nm for the OPA, the maximum output energy of the amplified SRS was about 0.73 mJ for the signal and 0.18 mJ for the idler, the energy conversion efficiency was 30.4% from the pump beam to the amplified third order Stokes component at 635.1 nm. The total efficiency would be as high as 37.9% if the output of the idler is also included. The corresponding spectral line width of the amplified Raman pulse was 11.8 cm−1 with a pulse width of 10.9 ps and a peak power of 67 MW. The OPA system was also used as an amplifier for very weak Raman signal, the slope gain factor of this amplifier was found to be as high as 4.1 × 107 and the energy detection limit was as low as 14.8 aJ per pulse, or 48 photons at 635.1 nm, in particular. Such a detection limit corresponds to approximately 0.5 photons per pulse if the time-gate of the OPA is reduced to 150 fs and it is about the same as or even better than a recently report on the 0.75 photons detection limit for a 150-fs OPA of coherent signal at 800 nm. 相似文献
20.
We demonstrate a continuously wavelength-spacing-tunable and high-power multiwavelength fiber optical parametric oscillator based on the multiwavelength idler-output technique. The laser cavity for multiwavelength idler outputs is constructed by a pumped highly-nonlinear dispersion-shifted fiber as parametric gain medium, two highly-reflective chirped fiber Bragg gratings (CFBGs) and a superimposed CFBG as comb-like filter. At a pump power of 1.1 W, the idler output of 10 wavelengths around 1.56 μm is achieved with a wavelength spacing of 0.39 nm. The wavelength spacing can be continuously tuned from 0.39 to 1.0 nm by utilizing a cantilever beam-based chirp tuning method to change the FSR of the superimposed CFBG. Our experimental results show that the designed multiwavelength idler-output scheme can significantly increase the multiwavelength output power with a total output power of 98 mW and each idler-channel power of 16.3 mW. 相似文献