Diffused Optical Waveguides Research Articles

Correlation between compositional and refractive index profiles in LiNbO3:Zn diffused optical waveguides

Waveguides fabrication in Z- and X-cut LiNbO3 crystals by vapor zinc diffusion has been studied by secondary ion mass spectrometry and optical measurements. Compositional analysis of diffused substrates shows the formation of a Zn rich superficial layer, followed by a deeper region with decreasing Zn concentration. A subsequent thermal annealing process has been performed to let zinc ions further diffuse into the substrates. The composition profiles have been correlated with the refractive index profiles, reconstructed by optical reflectivity measurements. The results and the nature of the detected layers are discussed and correlated with previous x-ray studies obtained in the same samples.

Optical waveguides for surface spectroscopy: FePO4 thin-film/K+-doped glass composite optical waveguide systems having tapered velocity couplers

Basic characteristics were examined for optical waveguides (OWGs) composed of a thin-film OWG deposited onto a diffused OWG in order to construct OWG systems suitable for biochemical sensors and for monitoring surface chemical reactions. Conditions were examined experimentally in detail for adiabatic and nonadiabatic transition of the guided light from the K+-doped glass OWG to the FePO4 thin film by changing the length of the tapered velocity couplers made at the ends of the films. A miniband structure of the FePO4 film, 1 mm wide and having 0.5-mm slopes at the ends, was constructed for optical sensing. It exhibited high sensitivity despite the fact that the FePO4 OWGs were found to have a large attenuation coefficient, 60–80 dB/cm.

Theoretical study off silicon-clad planar diffused optical waveguides

A silicon-clad planar diffused optical waveguide structure is proposed and propagation characteristics for a wavelength of 0.6328 μm are investigated. The refractive index profile of the substrate is assumed to be a Gaussian profile and a maximum index change of 0.01 is also assumed. Computer modelling studies indicate that silicon-clad diffused optical waveguides exhibit a damped periodic oscillation in the attenuation and mode index curves. The attenuations of these waveguide structures are relatively small compared with those of the four-layer planar homogeneous waveguide structures reported by Batchman and McWright. The attenuation may be reduced with a low-index buffer layer. Furthermore, the attenuation and mode index are significantly altered by the conductivity changes of silicon.

Numerical solution of silicon-clad diffused planar optical waveguides

Computer modelling studies indicate that silicon-clad diffused planar optical waveguides exhibit a damped periodic oscillation in their attenuation and phase constant curves and that the attenuation is reduced significantly by reducing the maximum index change.

Finite-element solution of planar arbitrarily anisotropic diffused optical waveguides

The finite-element method for propagation in planar anisotropic diffused optical waveguides with arbitrary permittivity tensor is presented. A Galerkin procedure has been introduced to the finite-element formulation, to study both the nonleaky and leaky surface waves. The complex propagation constants are determined as a function of frequency for possible modes of propagation. The accuracy of the method has been checked by calculating the nonleaky and leaky surface waves of Ti-diffused LiNbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> waveguides with Gaussian index profiles. The numerical results of Ti-diffused LiNbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> waveguides with dielectric overlays are also presented and the effects of dielectric overlays on the propagation characteristics for the nonleaky and leaky surface waves are examined.

Analysis of partially metal‐clad and dielectric overlay‐loaded diffused optical waveguide

AbstractThe diffused optical waveguide is one of the most promising for use as an element of an integrated optical circuit, and optical functional devices such as an optical modulator and an optical switch can be composed of this waveguide. Analysis of this type of waveguide is difficult because the refractive index of the substrate is distributed continuously; there have been few studies on a waveguide with a metal cladding and a dielectric overlay and with the refractive index which is 2‐dimensionally inhomogeneous. We propose an approximate scalar finite‐element method which is applicable to a lossy diffused optical waveguide, and performed numerical analysis of a metal‐clad and dielectric overlay‐loaded diffused optical waveguide whose substrate has a 2‐dimensionally inhomogeneous refractive index profile. The results are presented in this paper.

Numerical analysis of planar arbitrarily anisotropic diffused optical waveguides using finite-element method

The finite-element method for light propagation in planar anisotropic diffused optical waveguides with arbitrary permittivity tensor is presented. The validity of the method is confirmed by comparing numerical results with the results of the well known multilayer-approximation method.

Correction to "Modal analysis of strip-loaded diffused optical waveguides by a variational method"

Correction to "Modal analysis of strip-loaded diffused optical waveguides by a variational method"

Modal analysis of strip-loaded diffused optical waveguides by a variational method

The propagating modes supported by strip-loaded three-dimensional diffused optical waveguides are analyzed in detail theoretically by using a variational method. Some typical numerical examples of the propagation constants and the field distributions are illustrated. The dependence of propagation characteristics on the geometrical parameters of the loading dielectric strip is discussed.

A study of submerged diffused optical waveguides

Diffused optical waveguides were prepared in which the maximum increase in the refractive index An was reached at some distance from the surface. A method was developed for the identification of the profile of such submerged waveguides by approximating it with a combination of a displaced parabola and an exponential function. This method was used in a determination of the distribution of the refractive index of 12- and 4-mode submerged glass waveguides.

Strip-loaded diffused optical waveguides

A strip-loaded diffused optical waveguide consists of a one-dimensional diffused guide with a narrow loading strip of dielectric deposited on the surface. Two-dimensional modes can exist in the diffused material, confined in depth by the diffusion and in width by the loading strip. The propagation constants of these two-dimensional modes are calculated. The requirements for the index of refraction and width of the loading strip are discussed along with the rate of decay of electric-field amplitude away from the strip. A numerical example typical of Ti-diffused LiNbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> is given.