Abstract: The present invention provides a biochip for testing biological substances comprising a plurality of binding sites, optical means for determining a specific binding event at each binding site, wherein the plurality of binding sites and the means for determining a specific binding event at each binding site are monolithically integrated into a single chip which is electrically powered and produces electrical signals in response to binding events at each binding site. The means for determining a specific binding event can include a micro-cavity light source formed in a semiconductor layer and a photodetector formed in the same semiconductor layer and further include a grating assisted vertical planar waveguide coupler for in-situ monitoring hybridization dynamics at each binding site via associated changes in refractive index.

Abstract: The present invention provides a biochip for testing biological substances comprising a plurality of binding sites, optical means for determining a specific binding event at each binding site, wherein the plurality of binding sites and the means for determining a specific binding event at each binding site are monolithically integrated into a single chip which is electrically powered and produces electrical signals in response to binding events at each binding site. The means for determining a specific binding event can include a micro-cavity light source formed in a semiconductor layer and a photodetector formed in the same semiconductor layer and further include a grating assisted vertical planar waveguide coupler for in-situ monitoring hybridisation dynamics at each binding site via associated changes in refractive index.

Abstract: The present invention provides a method of forming a planar optical waveguide comprising the steps of forming a silica-based waveguide at a first temperature which is below a melting temperature of material from which the waveguide is formed; and annealing a region of the waveguide at a second temperature which is greater than the formation temperature and less than a melting temperature of material from which the waveguide is formed, so as to alter an effective refractive index of the region. In one embodiment the step of annealing is preceded by the step of forming a thin film heater over the region of the waveguide, the heater being capable of heating the region to the second temperature. The first temperature is preferably low (below 400° C.) to maximize the range of annealing temperatures.

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: A photonic signal transmitting device comprising a first waveguide with a first core having a refractive index n1, and a second waveguide with a second core having an average refractive index n2>n1. The second core is formed with a transitional region having a refractive index that increases progressively, and the transitional region of the second core being in contact with the first core, either within or at the peripheral surface of the first core, whereby the refractive index in the device increases progressively from n1 to n2 with progression through the first to the second core. A contribution to the increase in refractive index from n1 to n2 may effectively be made by tapering the cross-sectional dimensions of the transitional region of the second core.

Abstract: A photonic signal transmitting device which comprises a first waveguide having a first core composed of a first material having a refractive index n1 and a second waveguide having a second core composed of a second material having an average refractive index n2>n1. The second core projects into the first core and is formed such that the effective refractive index of the device increases with progression into the second core from the first core. The effective refractive index of the device may be increased by forming the second core with a region which is tapered to provide an increasing cross-sectional area with progression into the second core. The effective refractive index of the device may also be increased by forming the second core such that its composition changes to increase the refractive index with progression into the second core.

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 forming a planar optical waveguide comprising the steps of forming a silica-based waveguide at a first temperature which is below a melting temperature of material from which the waveguide is formed; and annealing a region of the waveguide at a second temperature which is greater than the formation temperature and less than a melting temperature of material from which the waveguide is formed, so as to alter an effective refractive index of the region. In one embodiment the step of annealing is preceded by the step of forming a thin film heater over the region of the waveguide, the heater being capable of heating the region to the second temperature. The first temperature is preferably low (below 400° C.) to maximise the range of annealing temperatures.

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.

Abstract: A method of depositing a waveguide core in a trench formed between opposed sidewalls of adjacent first and second cladding structures of a planar substrate. The method comprises the steps of depositing a waveguide material in the trench, preferentially etching the deposited waveguide material at or near upper regions of the opposed sidewalls, and controlling at least one parameter of the deposition process so as to form a waveguide core in the trench from the deposited waveguide material. The preferential etching step may be conducted in a manner which increases optical confinement in the deposited waveguide core in the trench, or in a manner which reduces shadowing effects in the trench.

Abstract: The present invention provides a method of depositing a cladding layer over external surfaces of a waveguide structure formed on a planar substrate, the waveguide structure comprising a planar waveguide core formed on the planar substrate and a raised structure formed on the planar substrate adjacent the waveguide core. The invention allows high-aspect-ratio gaps in a planar optical waveguide structure to be filled without incorporating macroscopic or microscopic voids. In one embodiment, the method comprises depositing a cladding material over the planar waveguide structure, etching the deposited cladding material so as to reduce shadowing effects between the waveguide core and the raised structure during the deposition of the cladding material, and controlling at least one parameter of the deposition so as to form a cladding layer front the deposited material. In another embodiment, the method involves modifying the profile of the waveguide structure before depositing the cladding layer.

Abstract: A device for processing an optical signal, the device comprising a processing element monolithically integrated with a planar silica-based waveguide structure in which the optical signal propagates.

Abstract: The invention provides a method of modifying a planar waveguide core formed on a planar substrate and having at least one rough sidewall. The method comprises the steps of forming an overlayer having substantially the same refractive index as the waveguide core over each rough sidewall of the waveguide core so as to smooth over the sidewall roughness; and etching back the overlayer to form a desired waveguide structure with reduced sidewall roughness, wherein the rough sidewalls of the original waveguide core remain substantially coated with overlayer material in the desired waveguide structure. The roughness of the original sidewalls of the waveguide core is effectively reduced by leaving their coated with the overlayer material, which has been etched back. This leaves smoother sidewalls in the desired waveguide structure when compared with the original sidewalls of the waveguide core. The invention is particularly useful for reducing sidewall scattering losses in planar waveguide optical amplifiers.

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 metal-oxide-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.

Abstract: The invention concerns a method of forming a thin film electro-optic waveguide. In one embodiment, the method comprises forming a platinum film on a substrate, forming a PLZT film on the platinum film, and forming a PZT film on the PLZT film. The PLZT film has a lower refractive index than the PZT film. The PZT film functions as a waveguide core and the PLZT film functions as an optical buffer layer for optically isolating the PZT film from the platinum film. When the structure is thermally processed, the platinum film promotes the crystallinity in the PLZT film, which in turn promotes crystallinity in the PZT film. The invention is particularly useful for integrating non-silica-based electro-optic materials with silica-based waveguide structures. The invention also concerns an optical waveguide device formed by the method.

Abstract: The present invention provides a method of manufacturing a polarisation-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 vapour 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 polarisation 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.

Abstract: The invention relates to a method for etching of silica-based layers/substrates by reactive ion etching system (10) using an etching gas mixture of CHF3/AR through a photoresist mask. Reactive ion etching is carried out under conditions of simultaneous isotropic deposition of a carbon-based polymer where the polymer deposition rate is controlled by adjusting process control parameters of RF power, sample temperature, O2 and CF4 additions.