Table of contents

Planar optical waveguides, permitting light-propagation in only two dimensions, can be used to form images of one-dimensional objects. In one arrangment, the paths of light-rays on the guide are determined by the distribution of the effective refractive index over the regions of the guide, resulting in two-dimensional optical systems. Another possibility, existing in thick, multimode planar guides is the utilisation of self-focussing or self-imaging properties. All these imaging methods are reviewed, with particular emphasis on the most recent method of self-imaging.

Power is radiated from any imperfection in an optical dielectric rod transmission line, causing signal loss and crosstalk. On the other hand power can be fed into optical waveguides only at discontinuities. A survey is given on the radiation and transmission properties of six inhomogeneities in single mode optical waveguides: a free end, a gap, an axes offset, a step in diameter, a corner and a bend. Each problem is illustrated by a picture of the electromagnetic field showing constant amplitude and constant phase contours which have been measured using microwave models. Comments are given an the theoretical methods used to analyze the discontinuities and some results of the analysis are mentioned.

The basic properties, applications and future potential uses of leaky waves in integrated optics are presented. It is first noted that, in addition to surface waves, the fields excited by realistic sources along thin films also include leaky waves. These fields can be described by inhomogeneous plane waves that bounce between the film boundaries and radiate energy into the exterior open regions. Leaky wave fields on multilayered and periodic media are examined and their role in beam and waveguide couplers is discussed. Finally, the construction of structures having variable leakage is described and their capabilities in providing a wide range of beam transformations are outlined.

When a beam of light is totally reflected by a plane interface, a translation depending on its polarization occurs: one shift L_x is parallel to the incident plane π and the other L_y is perpendicular to π. Both the longitudinal L_x and the transverse shifts L_y are quantized, each having two eigenvalues which are the principal linear polarization states for L_x and the circularly polarized states for L_y. Thus the longitudinal and the transverse shifts should not be simultaneously observable.

A very strong amplification of these shifts could be obtained by using a multilayered structure. Measurements have been done, giving 50 μm for L_x and 30 μm for L_y.

A new theory has recently been developed whereby local inhomogeneous plane wave fields of the form A(r) exp[ikS(r)], with A and S complex, are tracked in a manner analogous to that employed for local homogeneous plane wave (geometric optical) fields with real A and S. After a review of the theory, the present discussion involves application to evanescent fields exterior to curved dielectric layers supporting trapped modes. By this method, the propagating mode fields inside the layer are used to furnish fields at the layer boundaries, which serve as initial values for the tracking of weakly evanescent fields in the exterior region. The tracking proceeds by first determining the « phase paths » and phase fronts of the evanescent field and therefrom, by suitable integration along such paths, the complex phase S and the complex amplitude A. The degree of evanescence of the field is intimately connected with the configuration of phase paths and phase fronts which thus provide physical insights similar to those gained from ray diagrams for non-evanescent waves. Because the fields are tracked locally, the method has considerable versatility in dealing with perturbations, scattering, etc., of evanescent waves.

Physicochemical treatments are proposed to optimize the properties of negative photoresists. These materials are used to realize phase filters and components for integrated optics.