Diffraction-limited geodesic lens: a search for substitute contours.

Diffraction-limited geodesic lens contours are compared with algebraic and transcendental contours. Curvature errors are analyzed for lenses between f/0.68 and f/10. It is shown that certain oblate ellipsoids of revolution closely approximate the diffraction-limited contour above f/3.0. Aberrations are analyzed, and a simple formula with tabulated constants provides a method for finding the closest approximation contour ellipse for a desired f/No.

Fiber-optic rotation sensor technology.

A concept for an all-waveguide fiber-optic rotation sensor is discussed, and the results of preliminary tests of key elements are described. A single channel waveguide coupler design provides the functions of an optical switch, a 3-dB beam splitter, a phase retarder, and a signal modulator, all of which may be formed on the same chip and interconnected by channel single-mode waveguides. Preliminary test results for the waveguide coupler and for a rotation sensor without the coupler are presented. Signal processing, polarization control, and interconnection of the waveguide components are discussed.

Design of planar star couplers for fiber optic systems.

A horn structure within a planar fiber optic star coupler has been shown by computer design to significantly reduce if not eliminate the packing fraction loss associated with the coupler geometry. The ray tracing design procedure is used to characterize the partitioning of light to the various ports, and the losses are tabulated. An eight-port planar star is used to illustrate the design capabilities.

Determination of ray directions coupled out of waveguides through prisms and gratings.

Prism or grating couplers are used to couple out guided modes propagating in optical waveguides. The directions of the beams propagating out of the guided medium are evaluated, in general, with the intent to assess the effect of the coupler on the propagation direction. In particular, the results are applied for the determination of m-line curvatures and beam deflectors. It is interesting to point out that deflections in a direction lateral to the coupling structure depend only on the relative effective index of refraction of the guided mode and that of the surrounding medium and are not affected by the coupler itself.