TE modes in a slab waveguide bounded by nonlinear media

A theory is presented of guided TE modes in a one-dimensional slabe waveguide bounded by nonlinear media with intensity dependent refractive indices. It is shown that this is a straightforward generalisation of linear slab waveguide theory with the modes parametrised by the power flow down the guide. Illustrative dispersion curves and mode shapes are discussed.     

Conversion of optical modes in an absorbing magnetogyrotropic waveguide

The features of mode conversion in an absorbing magnetogyrotropic waveguide are investigated by a coupled-wave approach. It is shown that absorption leads to an additional contribution to the coupling of both identically and orthogonally polarized modes. A new waveguide regime for mode conversion, in which there is no oscillatory energy exchange between modes, is revealed. The possibility of controlling the damping of the total field in a waveguide by varying the orientation of the magnetization in the waveguide layer is demonstrated. Zh. Tekh. Fiz. 68, 97–104 (June 1998)     

Modal dispersion curves of an optical waveguide with a core cross-section partially bounded by one turn of an equiangular spiral under weak guidance approximation

In this paper, we present a theoretical analysis of propagation of electromagnetic waves through a fiber with a spiral shape core cross-section with two cases. In one case the remaining unbounded part closed by a straight line and in other case remaining part not bounded by well defined line. Using Goell's point matching method under weak guidance condition modal characteristic equations for the lowest order modes are derived. The comparison of dispersion curves for two cases is also shown and interpreted.     

Properties of Gaussian waveguide modes of an optical cavity with a metamaterial

A theory of excitation of waveguide modes in an open two-mirror cavity containing layers with positive and negative refractive indices is proposed. Relations between the mirror curvatures and the thicknesses and refractive indexes of the layers at which the main mode has the Gaussian beam structure are derived. The stability of such cavities is analyzed.     

Conversion of waveguide modes in a periodic optical fiber

We investigate the distinctive features of the propagation and interaction of linearly polarized modes of an unperturbed step-index fiber, perturbed by a periodic distribution of the dielectric constant along the axis of the optical fiber. An analysis is made for unidirectional and opposite modes and two-mode excitation of the optical fiber. Ul’yanovsk Branch, Moscow State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, p. 40–46, March, 1998.     

梯形截面脊形介质波导导模的分析

本文给出用分区分离变量法计算梯形截面脊形介质波导传插特性与场分布的近似方法.所导出的数学表达式形式简单,物理图象清晰,可用袖珍计算器进行计算,计算工作量较小,所得结果与精确数值计算结果符合较好.     

WKB approximation for optical modes in a periodic planar waveguide

The application of the WKB method to a periodic dielectric graded-index waveguide is presented. Its justification is then verified by calculating the complex effective index of a graded-index waveguide operating in the basic TE₀ mode with three radiating diffraction orders.     

Collinear interaction of optical waveguide modes with an increasing space-charge wave

Collinear interaction of optical modes in a thin-film semiconductor waveguide with a space-charge wave increasing along its propagation direction has been investigated. Analytical solutions to the equations of coupled unidirectional and counterpropagating waveguide modes at their phase matching are obtained for the first time, and the dependence of the mode conversion efficiency on the space-charge wave amplification level, the coupling coefficient, and the length of the interaction region of optical modes is analyzed.     

Rabi oscillations of optical modes in a waveguide with dynamic modulation

We investigate the optical Rabi oscillations in a dual-mode slab waveguide that undergoes a spatial–temporal refractive index modulation. Frequency conversion is induced during Rabi oscillations since dynamic modulation is employed. We also show that the contrast of Rabi oscillations can be controlled by the initial phase of dynamic modulation, which can be tuned arbitrarily from zero to unity as the phase varies. The contrast of zero corresponds to the dynamic supermodes and unity refers to complete Rabi oscillations. It suggests that the phase can be a new degree of freedom to control optical Rabi oscillations. This study may find applications in optical sensors, switches and mode converters.     

Reflection-free one-way edge modes in a gyromagnetic photonic crystal

We point out that electromagnetic one-way edge modes analogous to quantum Hall edge states, originally predicted by Raghu and Haldane in 2D photonic crystals possessing Dirac point-derived band gaps, can appear in more general settings. We show that the TM modes in a gyromagnetic photonic crystal can be formally mapped to electronic wave functions in a periodic electromagnetic field, so that the only requirement for the existence of one-way edge modes is that the Chern number for all bands below a gap is nonzero. In a square-lattice yttrium-iron-garnet crystal operating at microwave frequencies, which lacks Dirac points, time-reversal breaking is strong enough that the effect should be easily observable. For realistic material parameters, the edge modes occupy a 10% band gap. Numerical simulations of a one-way waveguide incorporating this crystal show 100% transmission across strong defects.     

Energy exchange between parametric modes in a nonlinear optical medium

The behaviour of a nonlinear atom-field model for parametric oscillation is analysed. Constants of motion are found from which energy relations are obtained. Numerical results concerning the evolution of photon numbers and the atomic inversion stemming from given atom-field initial states are presented.     

Interface localized modes and hybrid lattice solitons in waveguide arrays

We discuss the formation of guided modes localized at the interface separating two different periodic photonic lattices. Employing the effective discrete model, we analyze linear and nonlinear interface modes and also predict the existence of stable interface solitons including the hybrid staggered/unstaggered lattice solitons with the tails belonging to spectral gaps of different types.     

Nonlinear dispersion equation and guided modes in a slab waveguide composed of a negative-index medium

We consider a slab waveguide made of a material with negative permeability and negative permittivity, the surrounding medium is conventional. By using the dispersion relation, we show the dispersion curves from the variation of the core width and other physical parameters. The associated energy flow for several thicknesses of the nonlinear layer waveguide is presented. We discuss possible new types of modes that can occur. It is found that the dispersion curves and the energy flow can be controlled by varying the thickness of the guide, the filling factor and the effective plasma frequency. A numerical simulation is done to well illustrate.     

Analysis of a Y-junction optical waveguide interleaver

A Y-junction optical planar lightwave circuit (PLC) interleaver is analyzed and a polymeric interleaver is fabricated. This interleaver is composed of two identical but reversed Y-junction components. The formula for channel spacing of this device is generated and influence factor of channel spacing is analyzed. The fabrication tolerance of this device is provided. Our analysis shows that there is a less than 2% deviation from the design value of 1.6 nm when the core width varies by 10%.     

Analysis of an inhomogeneous symmetric cladded slab optical waveguide

A detailed analysis of a symmetric cladded slab waveguide having a parabolic refractive-index profile in the core is carried out. Two techniques, one based on the step-index approximation and the other on the WKB approximation, are used to obtain the dispersion curves and the field plots for both the even and odd TE and TM-modes. An example of the practical relevance of the structure studied is given.     

Localized modes in a defectless photonic crystal waveguide at terahertz frequencies

We propose an idea to excite localized modes in a photonic crystal (PC) waveguide without ruining the discrete translational symmetry of the lattice. This can be done by arranging dispersive elements having negative permittivity over a desired frequency range into a periodic structure. We demonstrate numerically the realization of a cavity mode inside the air region of a geometrical defectless two-dimensional square-lattice PC consisting of polaritonic cylinders placed in air matrix. The corresponding waveguide structure in the form of a PC fiber supports the cavity mode as a guided mode to propagate along the guiding direction at very small propagation constant with near zero group velocity. These localized modes can be recognized as localized defectless modes inside the structure with four-fold symmetry.     

Effects of absorption on the propagation constants of guided modes in an asymmetric slab optical waveguide

We investigate how bulk losses of the thin film waveguide core influence the propagation constants of the modes of an asymmetric slab waveguide. Film absorption of a few hundreds inverse centimeters causes measurable shifts of the effective refractive indices, particularly for modes of higher order. We evaluate the error, that would be introduced into measurements of the refractive index and film thickness by the prism coupler method, if existing film losses were to be ignored.