Gaussian pulse transformation upon reflection from a resonant medium

The transformation and longitudinal shift of “the center of gravity” of a Gaussian pulse reflected from the plane surface of a semi-infinite resonant medium are analyzed numerically. The regions of carrier frequencies in which the maximum and minimum deformations of the reflected pulse are observed are determined.     

Transformation of a Gaussian pulse upon reflection from a resonant thin film structure

Peculiarities of Gaussian pulse reflection from a thin film with a resonance frequency dependence of the permittivity on a substrate with material parameters not depending on frequency are studied. Results of numerical analysis of equations determining the light field distribution in the reflected pulse are presented. The effect of the angle of incidence, carrier frequency, and duration of the incident pulse on the shift and transformation of the reflected pulse envelope is considered.     

Longitudinal shift and transformation of a Gaussian beam upon reflection from a thin film

Specific features of deformation of a Gaussian beam reflected from a thin film are studied on the basis of numerical analysis. A complex deformation of its profile is shown to be governed by three factors: by the character of behavior of the reflectance close to the angle of incidence, the Goos-Hanchen longitudinal shift, and by the shift in the direction of incidence of the beam, which is caused by the presence of the film-substrate interface. An approximate expression for the displacement of the “center of gravity” of the reflected beam is obtained.     

Total internal reflection of a Gaussian light beam

An approximate theoretical model for calculating the reflected and refracted fields of a Gaussian light beam at a plane interface between two isotropic media is formulated on the basis of a Fourier integral. In the vicinity of the critical angle of incidence (for total internal reflection) the model predicts the presence of two refracted beams, one displaced along the interface by an amount equal to the Goos-Hänchen shift; curvature of the phase fronts and nonalignment of the effective directions of energy and phase propagation occur for each beam, as in an anisotropic medium.     

Amplification of entangled light upon reflection from a cavity with nonlinear medium

The kinetic equation for the case of reflection of a broadband entangled light of a nondegenerate parametric source from a cavity is derived with the use of the technique of stochastic differential Ito equations. Statistical properties of the light reflected from a cavity with a nonlinear transparent medium, in which the process of special parametric interaction occurs, are considered on the basis of the obtained equation. Due to the integrals of motion, the entangled light, which is an EPR pair of continuous variables, can be amplified without destruction of the quantum correlation.     

Negative shift of a light beam reflected from the interface between optically transparent and resonant media

The lateral shift of a light beam reflected from the interface between an optically transparent dielectric and a medium for which the frequency dependences of the real and imaginary parts of the permittivity have a resonant form is investigated. At certain radiation frequencies and angles of incidence, a negative displacement of the reflected beam along the interface takes place.     

The parametric Doppler effect upon reflection of light from a moving smooth inhomogeneity of a medium

The reflection of probe radiation from a smooth inhomogeneity of characteristics of a medium that propagates with a relativistic velocity is analyzed. Equations that describe the propagation of forward and backward waves in an inhomogeneous medium are derived, conditions of occurrence of a Bragg resonance are formulated, and conditions for increasing the coefficient of reflection from the inhomogeneity are discussed.     

Transformation of singular light beam transverse structure in resonant media

The peculiarities of transformation of transverse structure for singular light beams propagating in a resonant medium have been analyzed theoretically. The influence of nonlinear absorption, self-focusing, and defocusing on the characteristics of optical vortices with different topological structure has been studied. The formation conditions and parameters for singular spatially localized structures have been characterized. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 509–515, July–August, 2008.     

Transformation of a Gaussian pulse reflecting from a nonlinear medium

The transformation of the envelope of a Gaussian pulse incident on and reflecting from a nonlinear dispersive medium is studied. It is shown that the pulse envelope transforms considerably upon reflection near the optical resonance frequency and the nonlinearity of the medium may appreciably distort the reflected pulse. Away from the resonance frequency, conditions may arise when the shift of the reflected pulse does not lead to the loss of the Gaussian form. In this case, the influence of nonlinearity is insignificant.     

Distortion of a simple Gaussian beam on reflection from off-axis ellipsoidal mirrors

We examine the distortion of a simple linearly polarised Gaussian beam on reflection from an off-axis ellipsoidal mirror. Expressions are derived for the distorted reflected fields and for the loss of power into higher order and cross-polarised modes.     

Transverse shift by total reflection of a circularly polarised light beam: theory and experimental proof

The Goos and Hänchen experiments of 1947 have shown that in total reflection the photons tunnel through the second medium (which we take to be the vacuum), whence a longitudinal shift x; Imbert's experiments of 1970 have shown that if the incident beam is circularly polarized there is also a transverse shift z, the sign of which depends on the helicity sign. We briefly explain this new phenomenon, first in terms of a generalized geometrical optics where the velocity and momentum of a spinning photon are non-collinear, then in terms of wave optics, using an appropriate class of solutions of Maxwell's equations.Presented at the International Conference on Gravitation and Relativity, Copenhagen, July 1971.     

Transformation of a Gaussian light beam reflected in the vicinity of the Brewster angle

Variations in the profile and shift of a Gaussian light beam upon reflection from a plane interface between a transparent dielectric and a medium with a complex refractive index are studied. The beam is assumed to be incident at angles close to the Brewster’s angle, where the effects of transformation of the beam profile are most substantial. Based on numerical analysis, the reflected beam profiles are obtained for different properties of the media, parameters of the incident beam, and positions of the plane of observation.     

Spectral shift of a stochastic electromagnetic Gaussian Schell-model beam in a Gaussian cavity

Spectral changes of a stochastic electromagnetic Gaussian Schell-model (EGSM) beam interacting with a Gaussian cavity are investigated. It is shown that the spectral shift is mainly determined by the degree of polarization of the initial beam and by the parameters of the cavity. Generically the blue shift occurs at on-axis points, while the red shift can occur at off-axis points. The condition under which the relative spectral shift is independent of the degree of polarization of the initial beam is analyzed.     

粗糙海面对高斯分布激光光束的反射模型推导

研究激光光束海面反射光强的方向分布特性对海上光电对抗等领域的工程实践具有重要意义.本文采用分形方法模拟粗糙海面,并在海面基准坐标系中建立起描述粗糙海面几何特征的数学方程,然后基于蒙特卡罗方法模拟高斯光束,依据几何光学原理在基准坐标系下推导了高斯光束的海面反射模型,采用该模型可以编程计算激光光束海面反射光强的方向分布.将模拟计算结果与实验结果进行了对比分析,结果表明该模型可以较好地反映激光光束海面反射光强的分布趋势,验证了模型的有效性.     

Propagation of a Gaussian beam in a gyrotropic medium

Propagation of a slightly diverging Gaussian beam in a gyrotropic medium [constitutive equation (1.1)] across the gyration vector g is considered. The polarization, phase, and geometrical features of the beams are elucidated. For a sufficiently small gyrotropy, the medium deflects the beams like a wedge while for a sufficiently large gyrotropy the medium focuses them like a cylindrical lens. For the field polarized along g, focusing automatically and completely eliminates the diffraction broadening of the beam along this direction.     

On a Gaussian beam in an amplifying medium

The model of a Gaussian beam in an amplifying medium is analyzed within the framework of the paraxial (quasi-optical) approximation. Upon violation of the obtained restrictions, the model leads to a physically inconsistent conclusion about an infinitely high radiation power after a passage of an ordinary Gaussian beam through a layer of the amplifying medium. The importance of a limitation on the transverse dimensions of the amplifying medium or of the introduction of intracavity angular selection is demonstrated. The fundamental mode in the form of a Gaussian beam appears in the model with a quadratic dependence of the gain on the transverse coordinates.     

Novel coordinate system for Gaussian beam reflection

A novel coordinate system for Gaussian beam reflection has been proposed in this Letter. Reflection from a spherical mirror is used to describe the novel coordinate system. One single segment of a general resonator is chosen to describe coordinate rotation in detail. Nonplanar ring resonators are chosen to show the application of the novel coordinate system. This novel coordinate system has been proved by two simple experiments and the problem existing in using the traditional coordinate system has been pointed out. This novel coordinate system is valuable for not only the designing of laser resonators but also Gaussian beam propagation analysis.