Abstract: Methods and apparatus for performing optical signal switching or other optical routing functions in an optical device or system, in which crosstalk induced by modal interference is suppressed by providing appropriate loss, gain and/or refractive index changes in different parts of a switch structure. An exemplary optical signal switch includes first and second branches each having a refraction-controlled section and an absorption-controlled section. An optical signal path over which an optical signal propagates in passing through the switch is selected to include a portion of at least one of the first and second branches, such that one of the first and second branches is a selected branch and the other branch is a non-selected branch.

Abstract: An optical waveguide for use in an optoelectronic integrated circuit and the associated method of manufacturing such a waveguide. The waveguide is formed by the successive layering of varied waveguide materials on a III-V semiconductor substrate, thereby producing a slab waveguide. The various layers within the slab waveguide are relatively thick, thereby producing a slab waveguide that is sized to be more compatible with an optical fiber and therefore more readily coupled to an optical fiber. The larger slab waveguide structure broadens the fundamental mode of the optical signal. However, multiple modes are also produced in the thicker slab waveguide that include higher order modes. A ridge structure is etched into the slab waveguide, wherein the width and height of the ridge structure are selected to impose lateral confinements on the higher order slab modes. The result is a waveguide that has a broadened fundamental mode yet is essentially single-mode.

Abstract: An optoelectronic modulator modulates an optical signal in response to an electromagnetic signal. The optoelectronic modulator includes a waveguide for conveying the optical signal, where the waveguide has an associated width, core thickness, and waveguide-electrode separation, and includes a optical index of refraction with respect to the optical signal and a microwave index of refraction with respect to the electromagnetic signal; and where the microwave index of refraction substantially matches the optical index of refraction for velocity-matching the optical signal and the electromagnetic signal through the waveguide. The waveguide may be disposed on an n-type doped substrate, may include a quantum well region disposed on the substrate, and may have a predetermined width for providing the matching of refractive indices.

Abstract: An optical switch array in an M.times.N configuration has a set of M input digital optical Y-branches; a set of N output digital optical Y-branch; and at least one S-bend interconnect waveguide connecting at least one input digital optical Y-branch to at least one output digital optical Y-branch, with the S-bend interconnect waveguide being adiabatically tapered for providing adiabatic modal evolution between the at least one input and output digital optical Y-branches. Each of the set of N output digital optical Y-branches has an associated branch separation point; and an output port of the at least one tapered S-bend interconnect waveguide is connected substantially adjacent to a respective branch separation point of a respective one of the set of N output digital optical Y-branch.