Abstract: A method of operating an optoelectronic device comprising an optical waveguide section, the optical waveguide section comprising a semiconductor core, the method comprising the steps of determining (401) a range for a negative bias voltage for the waveguide section for which an optical loss of the core is lower than an optical loss at zero bias for an operating wavelength range of the device, selecting (402) a bias voltage within the range and applying (403) the selected bias voltage to the waveguide section.

Abstract: A node is provided for implementing an asset sharing scheme in which the asset is mobile. The node being is to determine a location of the mobile asset in dependence on data, relating to the mobile asset, that is recorded in a data corpus authenticated by a distributed authentication protocol. The node may be configured to interact with other nodes to implement the distributed authentication protocol.

Abstract: A method of operating an optoelectronic device comprising an optical waveguide section, the optical waveguide section comprising a semiconductor core, the method comprising the steps of determining (401) a range for a negative bias voltage for the waveguide section for which an optical loss of the core is lower than an optical loss at zero bias for an operating wavelength range of the device, selecting (402) a bias voltage within the range and applying (403) the selected bias voltage to the waveguide section.

Abstract: An optical transmitter comprises a directly coupled MZ interferometer and driver circuit. The MZ interferometer comprises a pair of differentially driven MZ electrodes configured to impart RF signals to light travelling through respective arms of the interferometer, and to receive DC bias as a positive voltage via lower n-type cladding of the MZ interferometer. The lower n-type cladding is at a different positive DC potential to an upper plane RF ground of the MZ interferometer, but the lower n-type cladding and the upper plane RF ground have similar AC potential. The MZ interferometer also comprises a pair of resistors in series configured to provide differential RF termination of the MZ electrodes; and a capacitive coupling between a virtual ground formed at a centre point between the pair of resistors and an RF ground configured to provide common-mode RF termination. The DC supply for the driver circuit is applied to the centre point of the RF termination.

Abstract: An optical transmitter comprises a directly coupled MZ interferometer and driver circuit. The MZ interferometer comprises a pair of differentially driven MZ electrodes configured to impart RF signals to light travelling through respective arms of the interferometer, and to receive DC bias as a positive voltage via lower n-type cladding of the MZ interferometer. The lower n-type cladding is at a different positive DC potential to an upper plane RF ground of the MZ interferometer, but the lower n-type cladding and the upper plane RF ground have similar AC potential. The MZ interferometer also comprises a pair of resistors in series configured to provide differential RF termination of the MZ electrodes; and a capacitive coupling between a virtual ground formed at a centre point between the pair of resistors and an RF ground configured to provide common-mode RF termination. The DC supply for the driver circuit is applied to the centre point of the RF termination.

Abstract: A vehicle comprising: a locking mechanism for securing the vehicle; a user input device exposed to the exterior of the vehicle; a transceiver for communicating with a network external to the vehicle; and a processor configured for implementing a public/private key security algorithm and coupled to the transceiver for sending and receiving data by means of the transceiver, and coupled to the locking mechanism for disengaging the locking mechanism to permit access to the vehicle; the processor being configured to: receive from the transceiver a data block including a first token, the first token representing a public key of a user; receive from the user input device a second token; compare the first and second tokens to determine whether the second token is consistent with having been derived from a private key that forms a key pair with the public key; and if that determination is positive, cause the locking mechanism to be disengaged.

Abstract: An optical transmitter comprises a directly coupled MZ interferometer and driver circuit. The MZ interferometer comprises a pair of differentially driven MZ electrodes configured to impart RF signals to light travelling through respective arms of the interferometer, and to receive DC bias as a positive voltage via lower n-type cladding of the MZ interferometer. The lower n-type cladding is at a different positive DC potential to an upper plane RF ground of the MZ interferometer, but the lower n-type cladding and the upper plane RF ground have similar AC potential. The MZ interferometer also comprises a pair of resistors in series configured to provide differential RF termination of the MZ electrodes; and a capacitive coupling between a virtual ground formed at a centre point between the pair of resistors and an RF ground configured to provide common-mode RF termination. The DC supply for the driver circuit is applied to the centre point of the RF termination.

Abstract: There is disclosed a DBR laser and a method of use. The DBR laser comprises a phase section in a cavity of the DBR laser and configured to adjust an optical path length of the cavity. A DBR section comprises a frequency tuning system configured to adjust a Bragg frequency of the DBR section. A detector is configured to detect laser light transmitted through the DBR section.

Abstract: A waveguide structure including a waveguide having a thermally controllable section, and a method of manufacturing the structure. The waveguide structure comprises a plurality of layers. The layers comprise, in order: a substrate (306), a sacrificial layer (305), a lower cladding layer (303), a waveguide core layer (302), and an upper cladding layer (301). The lower cladding layer, waveguide core layer, and upper cladding layer form the waveguide, the waveguide has a waveguide core. The waveguide structure has a continuous via (307) passing through the upper cladding layer, waveguide core layer, and lower cladding layer and running parallel to the waveguide ridge (304) along substantially the whole length of the thermally controllable section. The waveguide structure also has a thermally insulating region (308) in the sacrificial layer extending at least from the via to beyond the waveguide ridge along the whole length of the thermally controllable section.

Abstract: A vehicle comprising: a locking mechanism for securing the vehicle; a user input device exposed to the exterior of the vehicle; a transceiver for communicating with a network external to the vehicle; and a processor configured for implementing a public/private key security algorithm and coupled to the transceiver for sending and receiving data by means of the transceiver, and coupled to the locking mechanism for disengaging the locking mechanism to permit access to the vehicle; the processor being configured to: receive from the transceiver a data block including a first token, the first token representing a public key of a user; receive from the user input device a second token; compare the first and second tokens to determine whether the second token is consistent with having been derived from a private key that forms a key pair with the public key; and if that determination is positive, cause the locking mechanism to be disengaged.

Abstract: A node is provided for implementing an asset sharing scheme in which the asset is mobile. The node being is to determine a location of the mobile asset in dependence on data, relating to the mobile asset, that is recorded in a data corpus authenticated by a distributed authentication protocol. The node may be configured to interact with other nodes to implement the distributed authentication protocol.

Abstract: A node is provided that is configured to interact with one or more other nodes to implement a distributed authentication protocol. The node is configured to receive data that is indicative of use of a physical asset, generate a usage fee to be assigned to one or more owners of the physical asset in dependence on the use data and record that usage fee in a data corpus authenticated by the distributed authentication protocol.

Abstract: A waveguide structure including a waveguide having a thermally controllable section, and a method of manufacturing the structure. The waveguide structure comprises a plurality of layers. The layers comprise, in order: a substrate (306), a sacrificial layer (305), a lower cladding layer (303), a waveguide core layer (302), and an upper cladding layer (301). The lower cladding layer, waveguide core layer, and upper cladding layer form the waveguide, the waveguide has a waveguide core. The waveguide structure has a continuous via (307) passing through the upper cladding layer, waveguide core layer, and lower cladding layer and running parallel to the waveguide ridge (304) along substantially the whole length of the thermally controllable section. The waveguide structure also has a thermally insulating region (308) in the sacrificial layer extending at least from the via to beyond the waveguide ridge along the whole length of the thermally controllable section.

Abstract: An optical transmitter comprises a directly coupled MZ interferometer and driver circuit. The MZ interferometer comprises a pair of differentially driven MZ electrodes configured to impart RF signals to light travelling through respective arms of the interferometer, and to receive DC bias as a positive voltage via lower n-type cladding of the MZ interferometer. The lower n-type cladding is at a different positive DC potential to an upper plane RF ground of the MZ interferometer, but the lower n-type cladding and the upper plane RF ground have similar AC potential. The MZ interferometer also comprises a pair of resistors in series configured to provide differential RF termination of the MZ electrodes; and a capacitive coupling between a virtual ground formed at a centre point between the pair of resistors and an RF ground configured to provide common-mode RF termination. The DC supply for the driver circuit is applied to the centre point of the RF termination.

Abstract: A waveguide structure including a waveguide having a thermally controllable section, and a method of manufacturing the structure. The waveguide structure comprises a plurality of layers. The layers comprise, in order: a substrate (306), a sacrificial layer (305), a lower cladding layer (303), a waveguide core layer (302), and an upper cladding layer (301). The lower cladding layer, waveguide core layer, and upper cladding layer form the waveguide, the waveguide has a waveguide core. The waveguide structure has a continuous via (307) passing through the upper cladding layer, waveguide core layer, and lower cladding layer and running parallel to the waveguide ridge (304) along substantially the whole length of the thermally controllable section. The waveguide structure also has a thermally insulating region (308) in the sacrificial layer extending at least from the via to beyond the waveguide ridge along the whole length of the thermally controllable section.

Abstract: There is disclosed a DBR laser and a method of use. The DBR laser comprises a phase section in a cavity of the DBR laser and configured to adjust an optical path length of the cavity. A DBR section comprises a frequency tuning system configured to adjust a Bragg frequency of the DBR section. A detector is configured to detect laser light transmitted through the DBR section.