Abstract: A method and apparatus for fabricating silica-based waveguide devices on a substrate using a low temperature PECVD process using a TEOS source material for depositing waveguide layers containing silica, the apparatus being arranged, in use, in a manner such that a liquid source material containing silicon is used during the PECVD.

Abstract: The present invention provides a planar optical waveguide amplifier for amplifying optical communications signals when optically pumped by radiation of a pumping wavelength, the amplifier comprising: an optical buffer layer formed on a substantially planar substrate; an optically-transmissive metal-oxide-based waveguide core formed on the buffer layer, the core comprising aluminium oxide and a gain medium; and an optical cladding layer formed over the core. Preferably, the composition of the core predominantly comprises aluminium oxide and the gain medium comprises erbium and/or ytterbium. The waveguide core can be formed by reactively dc sputtering aluminium. The invention has the advantage of allowing higher erbium doping concentrations than is possible for silica-based amplifiers.

Abstract: The present invention provides an integrated optical device comprising a metaloxide-based optical planar waveguide amplifier monolithically integrated on a common substrate with at least one additional planar waveguide selected from a group comprising: a planar waveguide signal-processing circuit arranged to process an optical communications signal; and a planar waveguide pump-signal coupling circuit arranged to couple or decouple a pump wavelength to or from the amplifier; wherein the amplifier has a metal-oxide-based core comprising an optically-transmissive metal oxide material doped with a gain medium and is arranged to amplify an optical communication signal when optically pumped with a source of pump radiation. The amplifier can have a core composed of aluminium oxide doped with erbium and/or ytterbium. The signal processing circuit may comprise a multiplexer, demultiplexer, channel gain equalizer, N×M optical switch matrix, an optical modulator, or an add-drop multiplexer.

Abstract: The invention resides in a method of forming a waveguide structure comprising the steps of forming a silica based waveguide on a substrate; annealing one or more localised regions of said waveguide to permanently set the refractive index profile of said localised regions relative to other regions of said waveguide. In a particular form of the invention a core-forming layer is formed and selected regions of the core-forming layer are annealed to reduce their refractive, index thereby defining a core region therebetween. Other applications of the invention reside in reducing bend losses in bent waveguides, and forming long-period gratings in planar waveguides.

Abstract: The present invention provides a method of manufacturing a polarization-insensitive waveguide structure. The method comprises: depositing a buffer layer on a substrate; depositing a core layer on the buffer layer and etching the core layer so as to form a waveguide core; and depositing a silica-based cladding layer over the core by means of plasma-enhanced chemical vapor deposition (PECVD) in the absence of nitrogen or nitrogen-containing gases so as to complete the waveguide structure, wherein the cladding layer is deposited in a manner which substantially prevents polarization sensitivity in the waveguide structure. The cladding layer can be deposited with an intrinsic stress which cancels out any thermal stresses. The stress can be controlled by controlling the PECVD deposition conditions, such as power and ion bombardment.