Method of adiabatic modes in studying problems of smoothly irregular open waveguide structures

Basic steps in developing an original method of adiabatic modes that makes it possible to solve the direct and inverse problems of simulating and designing three-dimensional multilayered smoothly irregular open waveguide structures are described. A new element in the method is that an approximate solution of Maxwell’s equations is made to obey “inclined” boundary conditions at the interfaces between themedia being considered. These boundary conditions take into account the obliqueness of planes tangent to nonplanar boundaries between the media and lead to new equations for coupled vector quasiwaveguide hybrid adiabatic modes. Solutions of these equations describe the phenomenon of “entanglement” of two linear polarizations of an irregular multilayered waveguide, the appearance of a new mode in an entangled state, and the effect of rotation of the polarization plane of quasiwaveguide modes. The efficiency of the method is demonstrated by considering the example of numerically simulating a thin-film generalized waveguide Lüneburg lens.     

Eigenwave asymptotics for smoothly irregular plane anisotropic waveguide

An extension of method of horizontal rays and vertical modes developed for underwater acoustics to the spatially inhomogeneous anisotropic electrodynamic problem is proposed.Leningrad State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 7, 790–797, July, 1991.     

Numerical investigation of characteristics of laser radiation scattered in an integrated optical waveguide with three-dimensional inhomogeneities

Specifics of theoretical analysis of wave phenomena in irregular integrated optical waveguides are investigated. The object of the investigation and the main types of irregularities (smooth, statistical, and sharp) are described. The goals of the numerical modeling are formulated. The structure of the program and the general structure of the algorithm allowing numerical investigation of guided modes’ scattering from 3D-irregularities of an integrated optical waveguide are described. The dispersion relations of the TE and TM modes of the integrated optical waveguide under investigation, as well as field patterns of the radiating TE modes of the substrate and the laser radiation scattered from the three-dimensional guiding-layer inhomogeneities of an integrated optical waveguide, are presented. The results are analyzed in detail. The methods developed can be used for numerical investigation of the characteristics of laser radiation scattered in various optical waveguides with three-dimensional irregularities.     

Polymer optical waveguide based on integrated optics

The fabrication and characterization of refractive index profiles of multimode mode polymer optical waveguides is reported. Effect of annealing temperature on guided losses of polymer (polystyrene) thin film optical waveguide is also presented. Efficient coupling over a 110 nm spectral bandwidth was experimentally demonstrated with a prism-coupler designed to match the dispersion of a particular waveguide.     

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)     

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.     

Compact tunable three-dimensional polymer optical waveguide comb filter

A compact channel spacing tunable polymeric three-dimensional (3D) comb filter has been designed and fabricated. This comb filter is made of three waveguides laid in two different but parallel layers: one is in the lower layer and the other two are in the upper layer. These two waveguides in upper layer do not cross each other but instead each twice cross over the waveguide in the lower layer. At each crossing point an electrode heater is deposited on the top surface to adjust the coupling ratio between these guides. By supplying power to each heater pair, respectively, the channel spacing can be selected to be either 1.6 nm or 0.8 nm; in addition a flat-top spectral response may be obtained at the 1.6 nm channel spacing if power is supplied to both the heater pairs simultaneously.     

Rh-B doped polymeric optical waveguide for integrated optics

A systematic study of fabrication and characterization of rhodamine-blue (Rh-B) doped polystyrene waveguide is presented. Optical absorption and mode effective refractive index measurement was performed on the waveguides fabricated on glass substrate prepared by dip coating technique. It is observed that doping of dye increase the index of refraction of waveguides. The losses, however, decrease initially for dye concentration upto 0.1% and thereafter increase rapidly.     

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.     

Theory of waveguide light scattering in an integrated optical waveguide in the presence of noise

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.     

Femtosecond waveguide writing: a new avenue to three-dimensional integrated optics

Using tightly focussed femtosecond laser pulses, waveguides can be fabricated inside various glasses and crystals. This technique has the potential to generate not only planar but three-dimensional photonic devices. In this paper we present, to the best of our knowledge, the first true three-dimensional integrated optical device, a 1×3 splitter fabricated in pure fused silica. The optical properties of this device and possibilities for the fabrication of complex high-density integrated optical elements are discussed. Received: 23 December 2002 / Accepted: 6 January 2003 / Published online: 28 March 2003 RID="*" ID="*"Corresponding author. Fax: +49-3641/65-7680, E-mail: nolte@iap.uni-jena.de     

Intrinsic integrated optical temperature sensor based on waveguide bend loss

Curvature of a multimode integrated optical waveguide reduces the numerical aperture and induces radiation losses. In this paper, we study this phenomenon and we present a geometrical approach to calculate the local numerical aperture and the intensity attenuation. We exploit the bending effect on the local numerical aperture to make a new intrinsic temperature sensor. The simulation results are validated for the silica/silicone integrated optical case. The principal performances of the silica/silicone temperature sensor are the extended temperatures range (−50 to 200 °C) with an excellent linearity response (1%) between 20 and 200 °C.     

Design and fabrication of a three-dimensional polymer optical waveguide polarization splitter

We present a design and fabrication of a three-dimensional polymer optical waveguide polarization splitter by taking into consideration of the induced birefringence effect of the polymer. We show that it is not possible to couple TM light from one waveguide to the other but evanescent coupling for TE light is possible. Hence the polarization splitter can be designed by considering TE mode coupling alone. This has an advantage of short interaction length of the device. Based on this consideration, we fabricated a polarization splitter with a TE extinction ratio of 15 dB and TM extinction ratio of 21 dB.     

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.