Abstract: In a ridge waveguide serial interferometer mode conversion is induced by a first mode conversion section, a phase difference between modes is introduced by propagation over a length of waveguide and optical interference is produced following further mode conversion induced in a second mode conversion section. The first mode conversion section has a first radius of curvature, which is equal to a second radius of curvature of the second mode conversion section. The ridge waveguide interferometer advantageously provides an equal phase dependency as a function of temperature.

Abstract: A light detector measures optical power of light incident thereon. Using a beam steering device that is rotatable about two orthogonal axes, wavelength components of different channels are scanned onto the light detector in accordance with programmable parameters. The programmable parameters specify the light detector to which the wavelength components are directed, the order the wavelength components are monitored by the light detector, and the time duration over which each of the wavelength components is monitored by the light detector.

Abstract: An optical wavelength monitor photodiode integrated on a wafer and/or an optical device and coupled to optical components thereof provides wavelength measurement. The optical wavelength monitor includes a photodiode configured to output a signal that is representative of a wavelength of the light. An additional photodiode may be included in the optical wavelength monitor, each photodiode differing from the other in operating characteristics. The monitor may be used in testing the optical device while in wafer form and when the optical device has been cleaved from the wafer at the bar level. Testing/monitoring of the optical device may also be performed during use, for example, to control the wavelength of a laser such as a tunable laser.

Abstract: A Mach-Zehnder interferometer (MZI) incorporates a tunable multimode interference (MMI) coupler comprising a tunable MMI coupler with a tuning electrode on a surface of a tunable MMI region and an electrically insulating region provided within the tunable MMI region. The MMI region is tunable in response to detection of a photocurrent by a photodetector section. Such a tunable MZI is particularly advantageous in enabling a split ratio of an optical splitter, the split ratio and the splitter to be controlled in a particularly efficient manner.

Abstract: The invention relates to a lens comprising two or more seating surfaces and an optical axis offset from the center of the lens such that the optical axis is spaced by a first distance from a first seating surface and by a second distance from a second seating surface. The first and second distances are different so that the lens can be orientated to provide at least two different optical axis heights depending upon which seating surface is chosen to seat the lens.

Abstract: A tunable external cavity laser for use as a pump laser in an optical amplifier such as a Raman amplifier or erbium doped fibre amplifier comprising a semiconductor gain device (12) operable to provide light amplification, a diffraction grating (18) for selecting the wavelength of operation of the laser and a MEMs actuator for changing the selected wavelength. A plurality of gain devices can be coupled together to improve the bandwidth or gain of the optical amplifier.

Abstract: A light source package is disclosed for a Raman amplifier node having a primary optical fibre for carrying an optical signal and a secondary optical fibre for carrying the optical signal when the signal is rerouted from the primary optical fibre. The light source package includes a primary light source for emitting light into the primary optical fibre when the optical signal is carried by the primary optical fibre to induce Raman gain of the optical signal, and a secondary light source for emitting light into the secondary optical fibre when the optical signal is carried by the secondary optical fibre to induce Raman gain of the optical signal.

Abstract: The present invention provides a method and apparatus for phase aligning two optical signals within an optical transmitter to each other (and, in some embodiments, to a pulse carved optical signal) using integrated complimentary taps and a dither signal. The phase of a first signal may be intentionally offset relative to the phase of a second signal. Based on the offset, a correction factor may be calculated. The correction factor may be used to shift the phase of the first signal and/or the second signal in order to generally align the signals. This procedure may be automatically performed in a feedback loop to cause the signals to come into alignment and maintain the alignment of the signals during operation of the transmitter.

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 pump unit (402) for a Raman amplifier (400) including an optical fibre (401) carrying an optical signal (420) is disclosed. The pump unit includes at least two light sources (411, 412, 431, 432) for emitting light at different wavelengths into the fibre to induce Raman gain of the optical signal passing along the fibre, and a controller (409) for providing pulses to each of the light sources to control when they do and do not emit light. The controller is configured to control the width of the pulses to control the total power of the light emitted into the fibre.

Abstract: The present application describes methods and systems for use in a communications network. More specifically, a method of deploying an optical demodulator arrangement having at least one interferometer in a network that transmits an optical signal is provided. The optical signal may include one or more on-off-keyed signals and one or more DMPSK signals. In some embodiments, the DMPSK signal is a DQPSK signal. The network may include one or more of fiber spans carrying the signals. The interferometer may have a first optical path and a second optical path and a time delay is formed between the first and second optical paths. The method may involve determining a cross-talk penalty that results from cross-phase modulation between the channels, and determining a time delay value for the interferometer. The time delay value may be determined based at least in part on determined the cross-talk penalty.

Abstract: An adjustable array includes a plurality of optical devices. Each adjustable array device has an optical light output therefrom and is configured whereby the corresponding optical lights of the plurality of optical devices have a predefined nonequivalent relationship relative to one another with respect to an output parameter. In response to a drive signal, the plurality of optical devices are further configured to adjust the corresponding optical lights with respect to the output parameter while substantially maintaining the predefined nonequivalent relationship.

Abstract: A laser device having a semiconductor gain element optically coupled to an optical fiber by using an angled anamorphic fiber lens and including a wavelength-selective front reflector. The laser device possesses improved output characteristics such as a highly linear laser emission output, even when the amplification section produces a high amount of gain. Such a laser source can also be used in various applications such as pump lasers for fiber amplifiers or frequency doubling systems.

Abstract: An optical waveguide arrangement is provided which comprises an active ridge waveguide structure 12 formed by etching of a semiconductor substrate 1, 2, 3. There is also provided an auxiliary waveguide-like structure 8 formed on the substrate adjacent the active ridge waveguide structure 12 to control the etched profile of the active waveguide structure. The arrangement of the auxiliary structure 8 on the substrate controls the etched profile over the cross-section of the active waveguide structure 12 and along the length of the active waveguide structure 12. Advantageously, this arrangement reduces or eliminates the disadvantages associated with etch-process induced asymmetries in the shape of closely spaced waveguides.

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: An etalon has an effective cavity length that can be tuned to compensate for temperature-dependent frequency shift and/or for random variations in the manufacturing process. The effective cavity length of an etalon is adjusted by changing the orientation of a tuning plate positioned in the etalon cavity. A screw adjustment and bending beam spring are used to change tuning plate orientation and precisely tune the etalon resonance frequency after the manufacturing process has been completed. Orientation of the tuning plate is adjusted during operation of the etalon using a passive thermal compensation mechanism, such as a bimetal support arm, which is fixed to the tuning plate and configured to reposition the tuning plate with changing temperature.

Abstract: There is described a laser assembly for providing light at a switchable output wavelength. The assembly comprises first and second tuneable lasers, each configurable to emit light at a laser wavelength chosen from a range of wavelengths. Light is transmitted from the first laser while the second laser is retuned to change the chosen laser wavelength thereof. Each laser comprises one or more thermally sensitive control components for controlling the operation of the laser and an additional component electrode located adjacent to at least one of the one or more control components. The laser is configured so that the sum of electrical currents supplied to each control component and its corresponding additional component remains substantially constant in use.

Abstract: A method and apparatus for monitoring and controlling an optical node 100. The optical node 100 including one or more optical components 120, 121 or 122 connected by optical fibre carrying an optical signal 102. The optical signal 102 including a plurality of optical channels. A set of measurement sequences is determined, each measurement sequence defining a set of optical channels from the plurality of optical channels and a measuring sequence for measuring an optical property of the set of optical channels. A measurement sequence is selected from the set of measurement sequences based on the operating conditions of the optical node 100. The optical properties of the set of optical channels of the selected measurement sequence are measured. The measured optical properties are analysed to determine whether one or more optical components 120, 121 or 122 are causing the optical node 100 to operate outside the tolerance of a defined set of operating conditions.

Abstract: A Bragg grating has a local reflection strength which varies with position along the length of the grating so as to generate a non-uniform wavelength reflection spectrum, enabling compensation for a non-uniform gain profile of the gain section of a tunable laser. In another aspect, a Bragg comb grating is modulated by an envelope function which can also compensate for a non-uniform gain profile. The comb grating may be a phase change grating, with the envelope function shape being controlled by the length between phase changes and/or size of the phase changes.

Abstract: An enclosure for a laser package the enclosure being configured to receive a laser component within the enclosure, and further configured to receive for a driver integrated circuit (IC) (34) on the exterior of the enclosure, wherein the enclosure comprises first external electrical contacts (52) electrically connected to respective first IC electrical contacts (60), and second IC electrical contacts (62) electrically connected to respective first internal electrical contacts (64), wherein the first and second IC electrical contacts (60, 62) are configured for electrical connection to the driver IC (34). Heat dissipation of the driver IC is improved for the IC being mounted outside of the enclosure.