共查询到20条相似文献,搜索用时 656 毫秒
1.
A. A. Egorov 《Optics and Spectroscopy》2010,109(4):625-634
The eigen and noneigen (leaky) modes of a three-layer planar integrated optical waveguide are described. The dispersion relation
of a three-layer planar waveguide and other dependences are derived, and the cutoff conditions are analyzed. The diagram of
propagation constants of the guided and radiation modes of an irregular asymmetric three-layer waveguide and the dependence
of the electric field amplitudes of radiation modes of substrate on vertical coordinate in a tantalum integrated optical waveguide
are presented. The operating principles of an absorption integrated optical waveguide sensor are investigated. The dependences
of sensitivity of an integrated optical waveguide sensor on the sensory cell length, the coupling efficiency of the laser
radiation into the waveguide, the absorption cross-section of the studied material, and the level of additive statistical
noise are investigated. Some of the prospective areas of application of integrated-optical waveguide sensors are outlined. 相似文献
2.
I. E. Golentus A. Yu. Gaevskii 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2014,8(4):651-658
X-ray-beam propagation through a parallel-plate waveguide is investigated with allowance for grazing-incidence Bragg diffraction at the crystalline structure of the plates. Expressions for the waveguide modes are derived. It is demonstrated that undamped waveguide modes exist at angles exceeding the critical value (total external-reflection angle), thereby making it possible to increase the angle of capture of radiation incident on the waveguide. The calculated output intensities of the waveguide are compared with the waveguide-mode intensities in absence of grazing-incidence diffraction in the waveguide material. 相似文献
3.
Optical second harmonic generation (SHG) in the form of Cerenkov radiation from ion-implanted lithium niobate (LiNbO3) channel waveguides is analyzed by directly resolving the wave equations. Useful formula of the SHG efficiency is derived and expressed in terms of waveguide parameters. Numerical examples are plotted for LiNbO3 crystals. The results enable the optimization of waveguide design for efficient second harmonic generation in the Cerenkov configuration. 相似文献
4.
A. D. Lapin 《Acoustical Physics》2000,46(3):367-369
The radiation of a piston in a rectangular waveguide whose wall is a baffle for the piston is considered. Simple asymptotic formulas for the real and imaginary parts of the piston radiation impedance are derived. 相似文献
5.
扇形波导可作为高功率微波圆柱共形波导缝隙阵天线的基本单元。分析了扇形波导中主模场分量,根据实际情况对主模场进行了合理近似。采用互易定理推导由波导主模横向场分量和缝隙场分量表示的波导场分量的前向或后向散射系数。根据波导传输线理论,将波导宽边纵缝等效为并联导纳,再根据波导边界条件得到扇形波导宽边谐振纵缝的归一化电导与波导散射系数之间的关系式。根据缝隙天线与振子天线的互补关系得到扇形波导谐振缝隙的辐射阻抗,结合波导功率平衡关系得到由波导横向场散射系数表示的缝隙辐射功率表达式,得到归一化电导的与谐振宽边纵缝的偏移位置、缝隙宽度、波导波长以及扇形波导尺寸参数之间的解析表达式。给出了算例,在波导中间区域,通过商用软件计算得到的电导与理论公式结果基本吻合。 相似文献
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7.
A. A. Egorov 《Radiophysics and Quantum Electronics》2005,48(1):57-67
We develop a vector theory of waveguide monochromatic light scattering in an integrated optical waveguide with arbitrary three-dimensional irregularities in the presence of noise. The electrodynamical problem of laser radiation scattering in an irregular waveguide is solved by the method of coupled modes with the help of the theory of perturbations. The approximate solution of the inhomogeneous three-dimensional wave equation is derived by the method of modes and the method of Greens functions. The obtained Greens function is analyzed for the cases of propagating and evanescent modes of an irregular asymmetric optical waveguide. Analytical formulas for the near- and far-zone radiation fields are presented. A preliminary analysis of these formulas is given.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 1, pp. 63–75, January 2005. 相似文献
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9.
On the propagation and interaction of ultralow-frequency waves in a waveguide with gyrotropic plasma
The propagation of ultralow-frequency (ULF) electromagnetic waves in a waveguide filled with magnetoactive plasma is consieered
on the basis of the monoaxial crystal approximation which is more general than the MHD approximation. The formulas for the
phase and group velocities of the ordinary (magnetoacoustic) and extraordinary waves (similar to Alfvén waves in the MHD approximation)
are derived. It is shown that analysis outside the scope of the MHD approximation results in a finite (nonzero) velocity of
energy propagation of the extraordinary wave (Alfvén wave at the limit) along the waveguide. The possible waveguide mode triplets
satisfying the conditions of synchronism are found. Three-wave resonant parametric and nonlinear interaction between waves
with such characteristics leads to effective spectral transformation of the ULF radiation.
Radiophysical Research Institute, Nizhny Novgorod; State Technical University of Nizhny Novgorod. Translated from lzvestiya
Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, Nos. 1–2, pp. 111–122, January–February, 1997. 相似文献
10.
Theory of electromagnetic wave propagation in a plasma-filled corrugate waveguide immersed in a finite magnetized field
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The linear theory of electromagnetic radiation from a high-power backward-wave-oscillator (BWO), travelling-wave-tube (TWT) with plasma-filled, sinusoidally corrugate waveguide driven by an intense relativistic electron beam (IREB) has been derived and analysed numerically. A general dispersion relation is presented for analysing a plasmafilled corrugate waveguide immersed in magnetized plasma in this paper. It is shown that the linear theory developed here is in good agreement with the previous work. 相似文献
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12.
Jens Gottmann Dirk Wortmann Ion Vasilief Leonid Moiseev Dimitri Ganser 《Applied Surface Science》2007,254(4):1105-1110
Laser radiation is used both for the deposition of the laser active thin films and for the micro structuring to define wave guiding structures for the fabrication of waveguide lasers. Thin films of crystalline and amorphous neodymium doped Gd3Ga5O12 are grown on single crystal yttrium aluminium garnet by pulsed laser deposition using excimer laser radiation.Manufacturing of the laser active waveguides by micro structuring is done using femtosecond laser ablation of the deposited films. The structural and optical properties of the films and the morphology of the structured waveguides are determined in view of the design and the fabrication of compact and efficient diode pumped waveguide lasers. The resulting waveguides are polished, provided with resonator mirrors, pumped using diode lasers and the waveguide lasers are characterized. The spectroscopic properties of the amorphous waveguide are investigated and an infrared waveguide laser is demonstrated. To our knowledge, there have been no reports by other groups of the successful operation of a structured waveguide laser fabricated by this technique or of a waveguide laser made from amorphous neodymium doped Gd3Ga5O12. 相似文献
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14.
M. Zheltikov 《Journal of Experimental and Theoretical Physics》2003,97(3):505-521
The ways of achieving limiting waveguide enhancement of nonlinear-optical processes in microstructure and photonic-crystal fibers are studied. The waveguide enhancement of nonlinear-optical processes is shown to be physically limited because of the competition of diffraction and refractive-index-step radiation confinement. In the case of the limiting refractive-index step values for fused silica fibers, the maximum waveguide enhancement of nonlinear-optical processes is achieved with submicron fiber core diameters. The maximum waveguide enhancement of coherent anti-Stokes Raman scattering in a hollow microstructure fiber relative to the regime of tight focusing is shown to scale as λ 2/αa4 with radiation wavelength λ, the inner fiber radius a, and the magnitude of radiation losses α. 相似文献
15.
Aghamir F. M. Goodarzi P. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2010,38(1):10-18
16.
In short waveguides used in integrated optical circuits, the radiation field is often present in the guiding region of a waveguide as well as the guided modes. We show that this can be investigated efficiently by extracting the radiation part from the total input field and simulating its evolution along the waveguide by use of the beam propagation method. The results are presented for a single-mode waveguide and a waveguide junction excited by a Gaussian beam. For a noncentred excitation, a considerable fraction of the radiation power is still in the guiding region after propagation over several tens of micrometres, and can be coupled to guided modes past the junction. 相似文献
17.
The phenomenon of total external reflection (TER) of quasi-monochromatic X-ray radiation fluxes on a material interface and the effect of waveguide–resonator propagation of these fluxes in nanosize extended slit clearance, as well as a device operating on the basis of this effect—a planar X-ray waveguide–resonator—are briefly described. Experimental data on the formation of an X-ray flux by a composite X-ray waveguide–resonator are presented, and a model describing the decrease in the angular divergence of the formed flux without a decrease in the integral intensity is proposed. The model is based on the conception of partial angular tunneling of the radiation flux in the gap between two consequently mounted and mutually adjusted waveguide–resonators; the tunneling is implemented due to the interaction between interference fields of standing X-ray waves excited by the radiation transported by the slit clearance of these waveguide–resonators. 相似文献
18.
V. A. Balakirev I. N. Onishchenko D. Yu. Sidorenko G. V. Sotnikov 《Journal of Experimental and Theoretical Physics》2001,93(1):33-42
A wake field excited by a relativistic electron bunch in a semi-infinite metal waveguide filled with a dielectric consists of the Vavilov-Cherenkov radiation, the “quenching”-wave field, and transient radiation, which interfere with each other. An exact analytic expression for the transient component of the field of a thin relativistic annular bunch is derived for the first time. The evolution of the space distribution of a field excited by a finite-size electron bunch is numerically calculated. The excitation of the wake field by a periodic train of electron bunches in a finite-length waveguide is studied. 相似文献
19.
The problem of grating coupling of a focused incident beam under non-normal incidence into a slab waveguide is given a complete three-dimensional (3D) solution. The diffracted field is expressed as the Fourier integral of a regular part and of a singular part resulting from the existence of the coupled guided mode. A suitable expression of the field in the neighborhood of the pole and a rigorous definition of the modal field lead to a generalized coupled mode equation relating the incident field and the two-dimensional (2D) modal field propagating in the plane of the slab waveguide. The phenomenological parameters involved in the coupled wave equation: the propagation constant, the radiation coefficient as well as the modal field shape are derived from the exact treatment of plane wave diffraction in the same structure. The solution of the complete coupling problem is given in the particular case of a Gaussian incident beam, and of a high index step-index waveguide. 相似文献
20.
A section of an optical waveguide having thickness less than the mode cutoff value adjoining a section having thickness greater than this value serves as an input-output optical waveguide coupler. Expressions for the radiation pattern of this coupler, the angle at which the maximum occurs, and the angular beam width are derived. Calculations of these quantities as a function of coupler thickness for several waveguide-substrate structures applicable at λ = 10.6 μm are presented. Radiation patterns with small angular widths that result in high coupler efficiencies are found to occur when the waveguide and substrate refractive indices are nearly equal. 相似文献