Abstract: There is described an RF waveguide array. The array comprises a substrate comprising a plurality of optical waveguides, each waveguide being elongate in a first direction. An electrical RF transmission line array is located on a face of the substrate and comprises a plurality of signal electrodes and a plurality of ground electrodes, each electrode extending in the first direction. Each signal electrode is positioned to provide a signal to two respective waveguides. The ground electrodes include at least one intermediate ground electrode positioned between each pair of signal electrodes. Each intermediate ground electrode includes a portion extending into the substrate.

Abstract: A chip comprising a bonding pad region and a transmission section. The bonding pad region has a first impedance, and is configured for electrical connection to an external transmission line. The transmission section extends away from the bonding pad region and has a second impedance. The bonding pad region is configured to enable field confinement and field matching between the bonding pad region and the external transmission line, and the second impedance is not equal to the first impedance.

Abstract: An electro-optic modulator. The modulator is made as a plurality of discrete elements, and adjacent elements abut such that there are no free space optics between adjacent discrete elements. The modulator comprises a radio frequency, RF, element configured to modulate light passing through the element based on an electrical RF input. The plurality of discrete elements comprises a first set of discrete elements fabricated from thin film lithium niobate, TFLN, and a second set of discrete elements fabricated from silicon photonics, SiPh. The first set of discrete elements comprises the RF element.

Abstract: A chip comprising a bonding pad region and a transmission section. The bonding pad region has a first impedance, and is configured for electrical connection to an external transmission line. The transmission section extends away from the bonding pad region and has a second impedance. The bonding pad region is configured to enable field confinement and field matching between the bonding pad region and the external transmission line, and the second impedance is not equal to the first impedance.

Abstract: An electro-optic modulator. The modulator is made as a plurality of discrete elements, and adjacent elements abut such that there are no free space optics between adjacent discrete elements. The modulator comprises a radio frequency, RF, element configured to modulate light passing through the element based on an electrical RF input. The plurality of discrete elements comprises a first set of discrete elements fabricated from thin film lithium niobate, TFLN, and a second set of discrete elements fabricated from silicon photonics, SiPh. The first set of discrete elements comprises the RF element.

Abstract: There is described an RF waveguide array. The array comprises a substrate comprising a plurality of optical waveguides, each waveguide being elongate in a first direction. An electrical RF transmission line array is located on a face of the substrate and comprises a plurality of signal electrodes and a plurality of ground electrodes, each electrode extending in the first direction. Each signal electrode is positioned to provide a signal to two respective waveguides. The ground electrodes include at least one intermediate ground electrode positioned between each pair of signal electrodes. Each intermediate ground electrode includes a portion extending into the substrate.

Abstract: The invention relates to a folded Mach-Zehnder modulator. The modulator may comprise a beam splitter configured to split an input light beam into a plurality of light beams. The modulator may comprise a plurality of Mach-Zehnder devices configured to receive one or more of the plurality of light beams. The modulator may comprise a U-turn section configured to receive light beams from the Mach-Zehnder devices and to change the direction of the light beams by substantially 180 degrees. The modulator may comprise a polarization management section configured to combine light beams received from the U-turn section and to output a polarization multiplexed phase modulated light beam.

Abstract: An electro-optic device 200 comprising a substrate in which first and second waveguides 202, 203 are formed. The device also comprises first and second electrodes 204, 205 comprising an optically transparent conductive material and including primary portions 204a, 205a overlying the first and second waveguides 202, 203 for electrically biasing the first and second waveguides. The device is configured such that one of the first and second electrodes includes one other portion 204b, 205b arranged alongside the primary portion 204a, 205a of the other of the first and second electrodes. This arrangement improves the electro-optic efficiency of the device without the need for a buffer layer in the electrodes.

Abstract: The invention relates to a folded Mach-Zehnder modulator. The modulator may comprise a beam splitter configured to split an input light beam into a plurality of light beams. The modulator may comprise a plurality of Mach-Zehnder devices configured to receive one or more of the plurality of light beams. The modulator may comprise a U-turn section configured to receive light beams from the Mach-Zehnder devices and to change the direction of the light beams by substantially 180 degrees. The modulator may comprise a polarisation management section configured to combine light beams received from the U-turn section and to output a polarisation multiplexed phase modulated light beam.

Abstract: A photonic assembly is described. The assembly comprises a substrate. An optical modulator (100) in or on the substrate has an output port coupled to an output waveguide (106) mounted in or on the substrate. A spiller waveguide (107, 108) is mounted in or on the substrate. The spiller waveguide (107, 108) has an input end (109, 110) physically separated from but proximate to the output waveguide (106) so as to collect light spilt from the output port or output waveguide (106). The modulator (106) may be a MZI modulator.

Abstract: A photonic assembly is described. The assembly comprises a substrate. An optical modulator (100) in or on the substrate has an output port coupled to an output waveguide (106) mounted in or on the substrate. A spiller waveguide (107, 108) is mounted in or on the substrate. The spiller waveguide (107, 108) has an input end (109, 110) physically separated from but proximate to the output waveguide (106) so as to collect light spilt from the output port or output waveguide (106). The modulator (106) may be a MZI modulator.

Abstract: An electro-optic device 200 comprising a substrate in which first and second waveguides 202, 203 are formed. The device also comprises first and second electrodes 204, 205 comprising an optically transparent conductive material and including primary portions 204a, 205a overlying the first and second waveguides 202, 203 for electrically biasing the first and second waveguides. The device is configured such that one of the first and second electrodes includes one other portion 204b, 205b arranged alongside the primary portion 204a, 205a of the other of the first and second electrodes. This arrangement improves the electro-optic efficiency of the device without the need for a buffer layer in the electrodes.

Abstract: A semiconductor ridge laser for coupling to a single-mode optical fiber has a ridge with a narrow parallel region, a diverging region, and then a wide parallel region that is adjacent to an output facet. A pump region for the laser may be less than the entire area of the ridge and have a “T” shape. Preferably, the ridge has a depth of about 350 to 550 nm and the narrow parallel region has a length of more than 0.4 times the overall length of the ridge. The wide parallel region at the output enables the laser to obtain low thermal resistance, which leads to a low operating temperature, a low power density in the laser cavity, and low astigmatism.

Abstract: A single-drive electro-optic Mach Zehnder modulator comprises a body of an electro-optically active material; optical waveguides are formed at least partly in that material and constitute a Mach Zehnder interferometer having two limbs providing alternative light paths between an input and an output so that interference may occur between light taking the alternative paths on recombination at the exit. At least two sets of three (or more) electrodes are provided, for subjecting longitudinally spaced sections of the limbs in “push-pull” to an electric field, and in at least one of the sections the waveguides of the two limbs are coupled.

Abstract: A bidirectionally pumped optical amplifier comprises an active fibre having two ends, a first WDM coupler and a second WDM coupler coupled to said ends, a first pump branch coupled to said first WDM coupler comprising a first laser and a grating, for introducing pump radiation in said active fibre in a first direction, and a second pump branch coupled to said second WDM coupler comprising a second laser, for introducing pump radiation in said active fibre in a second direction, opposite to said first direction. A portion of unabsorbed pump residual propagating in the first direction is coupled in one of the two pump branches towards the pump laser included in the pump branch, and locks the emission wavelength of the pump laser. The other pump branch preferably comprises an optical isolator for the pump radiation. Preferably, the pump lasers emit in the 980 nm window.

Abstract: A bidirectionally pumped optical amplifier comprises an active fibre having two ends, a first WDM coupler and a second WDM coupler coupled to said ends, a first pump branch coupled to said first WDM coupler comprising a first laser and a grating, for introducing pump radiation in said active fibre in a first direction, and a second pump branch coupled to said second WDM coupler comprising a second laser, for introducing pump radiation in said active fibre in a second direction, opposite to said first direction. A portion of unabsorbed pump residual propagating in the first direction is coupled in one of the two pump branches towards the pump laser included in the pump branch, and locks the emission wavelength of the pump laser. The other pump branch preferably comprises an optical isolator for the pump radiation. Preferably, the pump lasers emit in the 980 nm window.

Abstract: A bidirectionally pumped optical amplifier (200) comprises an active fibre (201), a first WDM coupler (204) and a second WDM coupler (205), a first pump: branch (220) coupled to said first WDM coupler (204) comprising a first laser (202) and a first grating (210), for introducing pump radiation into said active fibre (201) in a first direction, a second pump branch (230) coupled to said second WDM coupler (205) comprising a second laser (203) and a second grating (212), for introducing pump radiation into said active fibre (201) in a second direction, opposite to said first direction. The second laser has an output power PF. A first pump residual, having a power Pinj, is coupled into said second pump branch (230) from the active fibre (201) and injected into said second laser (203). The first pump branch (220) further comprises an optical isolator (211) for the pump radiation. The output power of the injected laser and the injected pump power residual are such that PF/Pinj>2.

Abstract: A semiconductor ridge laser for coupling to a single-mode optical fiber has a ridge with a narrow parallel region, a diverging region, and then a wide parallel region that is adjacent to an output facet. A pump region for the laser may be less than the entire area of the ridge and have a “T” shape. Preferably, the ridge has a depth of about 350 to 550 nm and the narrow parallel region has a length of more than 0.4 times the overall length of the ridge. The wide parallel region at the output enables the laser to obtain low thermal resistance, which leads to a low operating temperature, a low power density in the laser cavity, and low astigmatism.