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1.
激光二极管自混合干涉的计算分析和实验观察 总被引:4,自引:1,他引:3
实验上观察到自混合干涉信号的幅度仅仅为静态光强的百分之几.反馈光会引起激光二极管阈值电流减小,静态输出光强变化几倍,使激光二极管工作在实际的阈值电流之上.按三镜法布里-珀罗腔结构模型计算激光二极管的出射光强,由干涉函数主极大条件得出光频与反馈光的关系.计算出的自混合干涉信号的波形,以及自混合干涉信号的幅度与静态光强的比值均同实验测量结果一致.在τrC/τ1=22.8的情况下,复合谐振腔可同时有15个谐振模式,这些模随外腔长度的变化小于2.6×10-2cm-1,远小于法布里-珀罗谐振腔谐振模的线宽3.1cm-1,光频在内腔谐振模的线宽以内变化. 相似文献
2.
H. Haken 《Zeitschrift für Physik A Hadrons and Nuclei》1964,181(1):96-124
We consider the interaction of a set of atoms at random lattice sites with a decaying resonator mode. The optical transition is supposed to possess a homogeneously broadened Lorentzian line. The pumping is taken into account explicitly as a stochastic process. After elimination of the atomic coordinates a second order nonlinear differential equation for the light amplitude is found. In between excitation collisions this equation can be solved exactly if the resonator width is large as compared to all other frequency differences. In contrast to linear theories there exists a marked threshold. Below it the amplitude decreases after each excitation exponentially and the linewidth turns out to be identical with those of previous authors (for instanceWagner andBirnbaum), if specialized to large cavity width. Above the threshold the light amplitude converges towards a stable value, whereas the phase undergoes some kind of undamped diffusion process. We then consider the general case with arbitrary cavity width. If the general equation of motion of the light amplitude is interpreted as that of a particle moving in two dimensions, it becomes clear that also in this case the amplitude oscillates above threshold around a stable value which is identical with that determined in previous papers byHaken andSauermann neglecting laser noise. This stable value may, however, undergo shifts, if there are slow systematic changes of the cavity width, inversion etc. On the other hand the phase still fluctuates in an undamped way. After splitting off the phase factor the equations can be linearized and solved explicitly. With these solutions simple examples of correlation functions are calculated in a semiclassical way, thus yielding expressions for the line width above threshold. The results can also be used to evaluate from first principles correlation functions for different laser beams. As an example the complex degree of mutual coherence of two laser beams is determined. It vanishes if one of the lasers is still below threshold and its value is close to unity well above threshold for observation times small compared to the inverse laser linewidth. 相似文献
3.
Stimulated Brillouin scattering (SBS) is a key problem with the increasing power of fiber transmission systems. In this letter, a frequency-modulated fiber laser with an ultra-narrow linewidth is chosen as a light source. The SBS threshold is increased from 4.1 to 6.2 mW at 13-MHz frequency modulation amplitude for a 50-km G652 fiber. We also show that the SBS threshold increases with not only the frequency modulation amplitude, but also the modulation frequency. The modulation frequency should be high enough for effective modulation. 相似文献
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6.
E. Yu. Perlin 《Optics and Spectroscopy》2000,88(6):898-903
The amplitude and dispersion of the cubic susceptibility-tensor components χ ijkl (3) (?Ω; Ω, ω, ?ω) and of their combinations responsible for the Kerr and Faraday optical effects, as well as for the self-rotation of the polarization ellipse, are calculated within a simple model of a material with semiconducting spherical quantum dots without the inclusion of the excitonic effects and of processes of higher orders in field. It is shown that the susceptibilities increase smoothly in amplitude below the two-photon absorption threshold while remaining negative. Above the threshold, the susceptibilities exhibit sharp maxima associated with two-photon resonances. The regions with positive and negative real parts of the χ(3) tensor components alternate. The magnitude of the induced linear or circular birefringence obtained suggest the possibility of using the nonlinear optical polarization effects in these materials to control light with short, high-intensity light pulses. 相似文献
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V. G. Gusev 《Russian Physics Journal》1992,35(11):1019-1023
By the example of a time-averaged recording of the hologram of a focused image of a surface executing simple harmonic oscillation in its own plane, and diffusely scattering light, an analysis in the Fresnel approximation is made of the formation of an interference pattern for determining the amplitude of the oscillation. Theoretically and experimentally, it is shown that in the case of illuminating the scattering surface with coherent diffusely scattered radiation, the interference pattern is localized in the plane of formation of the Fourier image of the surface scattering the light. In the process, the size of the field in the Fourier plane is magnified, due to the amplification of the angular spectrum of the scattered waves. In monitoring the amplitude of the oscillation, this permits the sensitivity threshold to be lowered.V. V. Kuibyshev State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 30–34, November, 1992. 相似文献
9.
V. O. Martynov V. A. Mironov L. A. Smirnov 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(1):25-29
The quantum dynamics of an optical parametric oscillator under conditions of partially coherent pumping is considered. It is shown that if the pumping amplitude strongly exceeds a threshold value, the average number of emitted photons coincides with the estimate of the classical approximation, but the quantum state of light turns out to be entangled. Even though pumping noises reduce the magnitude of this entanglement, quantum correlations are not completely eliminated. 相似文献
10.
The KH 2 PO 4 crystal is a key component in optical systems of inertial confinement fusion (ICF).The microwaviness on a KH 2 PO 4 crystal surface is strongly related to its damage threshold which is a key parameter for application.To study the laser induced damage mechanism caused by microwaviness,in this paper the near-field modulation properties of microwaviness to the incident wave are discussed by the Fourier modal method.Research results indicate that the microwaviness on the machined surface will distort the incident wave and thus lead to non-uniform distribution of the light intensity inside the crystal;in a common range of microwaviness amplitude,the light intensity modulation degree increases about 0.03 whenever the microwaviness amplitude increases 10 nm;1 order diffraction efficiencies are the key factors responsible for light intensity modulation inside the crystal;the light intensity modulation is just around the microwaviness in the form of an evanescent wave,not inside the crystal when the microwaviness period is below 0.712 μm;light intensity modulation degree has two extreme points in microwaviness periods of 1.064 μm and 1.6 μm,remains unchanged between periods of 3 μm and 150 μm,and descends above the period of 150 μm to 920 μm. 相似文献
11.
A. F. Kabychenkov 《Physics of the Solid State》2006,48(3):516-523
Induced and parametric excitation of spin waves by a light field and light-induced spin echo are considered. The static and steady-state dynamic magnetizations in the light field are determined, and the phase diagrams of the system in magnetic and light fields are constructed. The threshold of parametric excitation, the amplitude of stationary oscillations, and the trajectories described by the end point of the magnetic moment vector are calculated for the case of light-induced nonlinear ferromagnetic resonance. The trajectories can be topologically different. The transition between states with different trajectories occurs as a phase transition. The parameters of the light-induced spin echo are determined. 相似文献
12.
The Nambu-Iona-Lasinio models with 4-dimensional cutting and dimensional-analytical regularization types are compared. It
is demonstrated that they describe two different models of light quark interaction. In the average-field approximation, the
behavior of the scalar amplitude differs in the threshold region. Unlike the 4-dimensional cutting regularization in which
the pole term corresponding to a sigma-meson can be separated near the threshold, the singularity of the scalar amplitude
in the dimensional-analytical regularization is non-pole; moreover, it disappears completely for a certain value of the regularization
parameter. One more significant difference between the two models is in the first-order expansion of the average field. The
calculated meson contributions to the quark chiral condensate and dynamic quark mass demonstrate that despite their relative
smallness, they can destabilize the Nambu-Iona-Lasinio model with 4-dimensional cutting regularization. On the contrary, the
model with dimensional-analytical regularization is stabilized, which is manifested through a shift of regularization parameter
values toward the stability region in which the contributions themselves decrease.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 20–31, April, 2006. 相似文献
13.
As an application of a preceding paper we set up a Fokker-Planck equation with quantum mechanically defined dissipation and fluctuation coefficients for a distribution function of the atomic variables (dipole moments and level occupation numbers) as well as of the lasing light amplitude in a laser with a homogeneously broadened line. Since the nonlinear coefficients can be linearized in appropriate coordinates well below and well above threshold, the equation can be solved with the Wang-Uhlenbeck method. Then it is easy to obtain correlation functions, spectral densities and expressions for linewidth. 相似文献
14.
A. Saint-Jalmes F. Gallet 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(4):489-494
Above a surface pressure threshold , we detect a buckled state in the low temperature solid phase of a phospholipid monolayer spread at the air-formamide interface.
Stable ripples are observed with a Brewster angle microscope, and light scattering provides measurements mNm-1, wavelength m and amplitude of a few nm for the deformation. A model, coupling the monolayer thickness and elongation, and consistent with the monolayer
texture, is also presented.
Received: 18 August 1997 / Revised: 9 December 1997 / Accepted: 29 January 1998 相似文献
15.
J. Jersák 《Nuclear Physics B》1974,80(2):322-340
Assuming that the scaling law interpolates the non-forward Compton amplitude in the resonance region, the threshold behaviour of the non-forward scaling function is determined from the threshold behaviour of the electroproduction scaling function. In addition the threshold behaviour of the deep inelastic annihilation scaling function is determined and found to be equal to that of the electroproduction scaling function. A Veneziano-like pole model for the non-forward Compton amplitude with these properties is constructed. In this model the scaling law interpolates the annihilation amplitude in the resonance region, too. 相似文献
16.
通过已搭建好的激光超声检测实验平台,在保持相同激光脉冲能量和相同探测位置的条件下,重点研究了点光源与线光源产生的超声信号的特点和区别。研究了不同探测位置点光源与线光源激发出的超声信号幅值以及产生的超声信号波形。实验发现:在同一探测位置下,将点光源换成线光源后,产生的超声信号幅值由1.3 V提高到1.7 V,提高了0.4 V;在探测位置逐渐增大的情况下,点光源激发出超声信号幅值的衰减幅度为75.78%,而线光源激发出的超声信号幅值的衰减幅度为34.92%。结果表明,在功率密度相同的情况下,线光源产生的超声信号要比点光源产生的超声信号幅值提高40.86%,产生较强的表面波,提高了信噪比。 相似文献
17.
All optical phase-only filtering correlator is constructed with an optically addressed ferroelectric liquid-crystal spatial
light modulator (FSLM) for a binarized input object and a twisted-nematic liquid-crystal spatial-light modulator for a computer-generated
phase-only filter. In order to improve the discrimination capability of a phase-only filtering correlator, a binarized amplitude
with maximum contrast in a FSLM is used for an object input. The contrast of binarized intensities can be maximized by adjusting
the rotation angles of a FSLM and polarizers. The threshold level of binarized input objects can be controlled by changing
the power of a laser incident on a FLSM. Experimental results with a high discrimination capability are presented to support
the numerical correlation performance. 相似文献
18.
Lasing in random media 总被引:2,自引:0,他引:2
Hui Cao 《Waves in Random and Complex Media》2003,13(3):R1-R39
A random laser is a non-conventional laser whose feedback mechanism is based on disorder-induced light scattering. Depending on whether the feedback supplied by scattering is intensity feedback or amplitude feedback, random lasers are classified into two categories: random lasers with incoherent feedback and random lasers with coherent feedback. A brief survey of random lasers with incoherent feedback is presented. It is followed by a review of our recent experimental work on random lasers with coherent feedback, including measurement of the lasing threshold, lasing spectra, emission pattern, dynamical response, photon statistics, speckle pattern and the investigation of relevant length scales. Large disorder leads to spatial confinement of the lasing modes, that is the foundation for the micro random laser. Some theoretical models of random lasers with coherent feedback are briefly introduced. The study of random lasers improves our understanding of the interplay between light localization and coherent amplification. 相似文献
19.
We observe a sharp threshold for dynamic phase locking in a high-Q transmission line resonator embedded with a Josephson tunnel junction, and driven with a purely ac, chirped microwave signal. When the drive amplitude is below a critical value, which depends on the chirp rate and is sensitive to the junction critical current I0, the resonator is only excited near its linear resonance frequency. For a larger amplitude, the resonator phase locks to the chirped drive and its amplitude grows until a deterministic maximum is reached. Near threshold, the oscillator evolves smoothly in one of two diverging trajectories, providing a way to discriminate small changes in I0 with a nonswitching detector, with potential applications in quantum state measurement. 相似文献
20.
基于金属-氧化物-半导体-场效应管(MOSFET)辐射损伤的微观机理,推导出了MOSFET经历辐照之后氧化层空穴俘获与阈值电压漂移之间关系的表达式.又根据MOSFET中1/f噪声产生的微观机理,建立了辐照之前MOSFET的1/f噪声功率谱幅值与阈值电压漂移量之间的定量关系,并通过实验予以验证.结果表明,辐照之前的1/f噪声功率谱幅值与辐照之后的阈值电压漂移量存在正比例关系,阈值电压漂移量可以反映出MOSFET内部的潜在缺陷的退化程度,因此,该模型有助于利用1/f噪声参量来表征MOSFET内部潜在缺陷的数量和严重程度. 相似文献