Abstract: A resonator modulator for modulating light in a photonic circuit, the modulator comprising: a capacitor formed of a ring-shaped insulating region sandwiched between an outer conductive region and an inner conductive region, wherein at least one of the outer conductive regions or the inner conductive regions is a polycrystalline semiconductor material.

Abstract: A process for refining a crude ethylene glycol stream comprising monoethylene glycol and at least one acid contaminant is disclosed. The process comprises reacting the acid contaminant with the monoethylene glycol in at least one reaction zone to form an ester and removing the ester in a separation step.

Abstract: A method of manufacturing a photonic chip. The method comprises providing a wafer comprising a silicon substrate, and a low refractive index layer above the silicon substrate, forming a first trench having a first height and a second trench having a second height by etching the low refractive index layer. The second height is greater than the first height and the second trench has a bottom surface that is closer to the substrate than a bottom surface of the first trench.

Abstract: A resonator modulator for modulating light in a photonic circuit, the modulator comprising: a capacitor formed of a ring-shaped insulating region sandwiched between an outer conductive region and an inner conductive region, wherein at least one of the outer conductive regions or the inner conductive regions is a polycrystalline semiconductor material.

Abstract: The invention provides a photonic chip comprising: a silicon substrate, an low refractive index layer above the silicon substrate, and a tapered waveguide above the low refractive index layer, the tapered waveguide having a first height at a first end of the tapered waveguide and a second height at a second end of the tapered waveguide, the second height being greater than the first height, and the tapered waveguide having a bottom surface that is closer to the substrate at the second end than at the first end.

Abstract: A method of fabricating an optical structure comprises providing a layer of single crystal crystalline silicon supported on an insulating surface of a silicon substrate; using etching to remove part of the silicon layer and define a side wall which is non-parallel to the insulating surface of the substrate; forming a layer of insulating material over the side wall; forming a further layer of silicon over at least the insulating material; and removing the silicon of the further layer to a level of the layer of silicon such that the layer of insulating material occupies a slot between a portion of silicon in the layer and a portion of silicon in the further layer, a thickness of the layer of insulating material defining a width of the slot.

Abstract: A silicon photonic chip is provided comprising a top silicon device layer; an insulating layer beneath the top silicon device layer; an intermediate silicon device layer beneath the insulating layer; a further insulating layer beneath the intermediate silicon device layer; a silicon substrate beneath the further insulating layer; and a first silicon waveguide, the first silicon waveguide being partially formed by a portion of the intermediate silicon device layer.

Abstract: The present invention relates to systems and methods for controlling the atmosphere in the cabin (1) of a vehicle. The system comprises a carbon dioxide removal conduit (2) comprising a regenerable carbon dioxide removal chamber (5,6) containing a carbon dioxide sorbent material and a regeneration circuit (7) arranged to expel the desorbed carbon dioxide at a location exterior (8) of the cabin (1) The system is operable to maintain a carbon dioxide level below 1000 ppm in the passenger cabin for a period of at least 5 minutes while restricting the flow of air from outside the vehicle into the passenger cabin to 10 L/s or less.

Abstract: An optical demultiplexer/multiplexer, comprising: a multimode interference waveguide; at least one first coupling waveguide which meets the multimode interference waveguide at least one first location and a plurality of second coupling waveguides which meet the multimode interference waveguide at a plurality of second locations which are spaced in a direction of transmission in relation to the at least one first location, with the at least one first coupling waveguide and the second coupling waveguides together with the multimode interference waveguide providing a first angled multimode interferometer which operates to demultiplex a first optical signal having optical channels of a plurality of wavelengths or multiplex optical signals of a plurality of wavelengths into a first optical signal having optical channels of the plurality of wavelengths; at least one third coupling waveguide which meets the multimode interference waveguide at least one third location and a plurality of fourth coupling waveguides whi

Abstract: An integrated photonic device comprising at least a first integrated photonic component supported by a substrate extending substantially in a plane of the device and optically isolating cladding facing the first integrated photonic component, the photonic device further comprising a waveguide formed by a deposited layer of group IV semiconductor material to extend on a slope in a direction out of the plane of the substrate, the waveguide arranged to, in use, couple light from/to the integrated photonic component through the optically isolating cladding.

Abstract: An integrated photonic device comprising at least a first integrated photonic component supported by a substrate extending substantially in a plane of the device and optically isolating cladding facing the first integrated photonic component, the photonic device further comprising a waveguide formed by a deposited layer of group IV semiconductor material to extend on a slope in a direction out of the plane of the substrate, the waveguide arranged to, in use, couple light from/to the integrated photonic component through the optically isolating cladding.

Abstract: A method of fabricating an optical structure comprises providing a layer of single crystal crystalline silicon supported on an insulating surface of a silicon substrate; using etching to remove part of the silicon layer and define a side wall which is non-parallel to the insulating surface of the substrate; forming a layer of insulating material over the side wall; forming a further layer of silicon over at least the insulating material; and removing the silicon of the further layer to a level of the layer of silicon such that the layer of insulating material occupies a slot between a portion of silicon in the layer and a portion of silicon in the further layer, a thickness of the layer of insulating material defining a width of the slot.

Abstract: A crude product stream of 1,4-butandiol and one or more of ?-butyrolactone, 2-(4-hydroxybutoxy)-tetrahydrofuran, 4-hydroxybutyl(4-hydroxybutyrate), and 3-(4-hydroxybutoxy)-tetrahydrofuran is supplied to a first distillation column. A side-draw of 1,4-butanediol and light components is removed, with the light components including at least some of those produced by reaction in the first distillation column. The stream is passed to a hydrogenation zone and subjected to hydrogenation in the presence of a hydrogenation catalyst. A 1,4-butanediol product stream having a reduced content of 2-(4-hydroxybutoxy)-tetrahydrofuran is recovered and passed to a second distillation column operated such that (4-hyroxybutyl)-4-hydroxybutyrate is removed as a bottom stream and a 1,4-butanediol stream is removed as overhead. The overhead stream removed is passed to a third distillation column and a purified 1,4-butanediol stream is recovered.

Abstract: In a process for the production of dialkyl succinate from a feedstock comprising maleic anhydride, feed in the liquid phase is provided to a reactor operated at a temperature of at least about 150° C. The feed is contacted with hydrogen at a pressure of at least about 300 psig in the presence of an acid tolerant catalyst and an alkanol wherein at least some of the carbon carbon double bonds of the maleic anhydride are hydrogenated to form succinic acid and that the heat generated promotes esterification to dialkyl succinate in situ. A stream of dialkyl succinate is recovered from the reactor.

Abstract: A process for production of dialkyl succinate from bio-succinic acid feedstock where solid bio-succinic acid is fed to a reactor to react with alkanol by autocatalytic esterification. Products from the reactor including unreacted succinic acid, mono alkyl ester, dialkyl ester, alkanol, water and impurities are sent to a reaction distillation column for esterification of succinic acid and further esterification of mono alkyl ester with upflowing alkanol. The bottoms products from the reaction distillation column including residual succinic acid, mono alkyl ester, dialkyl ester, impurities and alkanol are sent to a bottoms stream separation zone where di-alkyl ester is separated from alkanol, succinic acid, mono alkyl ester and impurities. The tops products from the reaction distillation column including alkanol, water and organic components are sent to a top stream distillation zone where alkanol is separated from water and organic components. The organic components are recycled to the reaction zone column.

Abstract: In a process for the production of dialkyl succinate from a feedstock comprising maleic anhydride, feed in the liquid phase is provided to a reactor operated at a temperature of at least about 150° C. The feed is contacted with hydrogen at a pressure of at least about 300 psig in the presence of an acid tolerant catalyst and an alkanol wherein at least some of the carbon carbon double bonds of the maleic anhydride are hydrogenated to form succinic acid and that the heat generated promotes esterification to dialkyl succinate in situ. A stream of dialkyl succinate is recovered from the reactor.

Abstract: An optical demultiplexer/multiplexer, comprising: a multimode interference waveguide; at least one first coupling waveguide which meets the multimode interference waveguide at at least one first location and a plurality of second coupling waveguides which meet the multimode interference waveguide at a plurality of second locations which are spaced in a direction of transmission in relation to the at least one first location, with the at least one first coupling waveguide and the second coupling waveguides together with the multimode interference waveguide providing a first angled multimode interferometer which operates to demultiplex a first optical signal having optical channels of a plurality of wavelengths or multiplex optical signals of a plurality of wavelengths into a first optical signal having optical channels of the plurality of wavelengths; at least one third coupling waveguide which meets the multimode interference waveguide at at least one third location and a plurality of fourth coupling waveguid

Abstract: The present invention relates to systems and methods for conrolling the atmosphere in the cabin (1) of a vehicle. The system comprises a carbon dioxide removal conduit (2) comprising a regenerable carbon dioxide removal chamber (5,6) containing a carbon dioxide sorbent material and a regeneration circuit (7) arranged to expel the desorbed carbon diocide at a location exterior (8) of the cabin (1) The system is operable to maintain a carbon dioxide level below 1000 ppm in the passenger cabin for a period of at least 5 minutes while restricting the flow of air from outside the vehicle into the passenger cabin to 10 L/s or less.

Abstract: An electro-optic device, comprising a layer of light-carrying material; and a rib, projecting from the layer of light-carrying material, for guiding optical signals propagating through the device. The layer of light-carrying material comprises a first doped region of a first type extending into the rib, and a second doped region of a second, different type extending into the rib such that a pn junction is formed within the rib. The pn junction extends substantially parallel to at least two contiguous faces of the rib, resulting in a more efficient device. In addition, a self-aligned fabrication process can be used in order to simplify the fabrication process and increase reliability and yield.

Abstract: An electro-optic device, comprising an insulating layer and a layer light-carrying material adjacent the insulating layer. The layer of light-carrying material, such as silicon, comprises a first doped region of a first type and a second doped region of a second, different type abutting the first doped region to form a pn junction. The first doped region has a first thickness at the junction, and the second doped region has a second thickness at the junction, the first thickness being greater than the second thickness, defining a waveguide rib in the first doped region for propagating optical signals. Since the position of the junction coincides with the sidewall of the waveguide rib a self-aligned process can be used in order to simplify the fabrication process and increase yield.