Abstract: An optical sensor having one or more sensing interference elements is disclosed. A first detector function generates a coarse optical path difference signal for example using a discrete Fourier transform of a detected interference spectrum, and a second detector function generates a refined optical path difference signal using the coarse optical path difference signal and for example a cross correlation of the interference spectrum with one or more sets of periodic transfer functions.

Abstract: An optical sensor having one or more sensing interference elements is disclosed. A first detector function generates a coarse optical path difference signal for example using a discrete Fourier transform of a detected interference spectrum, and a second detector function generates a refined optical path difference signal using the coarse optical path difference signal and for example a cross correlation of the interference spectrum with one or more sets of periodic transfer functions.

Abstract: An optical pressure sensor is disclosed having a pressure sensing optical cavity. A temperature sensing optical cavity at the sensing head is used by an interrogator to correct a pressure signal for effects of temperature. The optical cavities may be, for example, Fabry Perot cavities in the sensor head.

Abstract: An optical sensor having one or more sensing interference elements is disclosed. A first detector function generates a coarse optical path difference signal for example using a discrete Fourier transform of a detected interference spectrum, and a second detector function generates a refined optical path difference signal using the coarse optical path difference signal and for example a cross correlation of the interference spectrum with one or more sets of periodic transfer functions.

Abstract: An optical sensor is described for distinguishing between liquids of different refractive index, through strength of interference caused by an optical cavity having an exposed optical boundary in contact with such liquids. The sensor may be used, for example, to distinguish between water and aviation fuel in an aircraft fuel tank.

Abstract: An optical pressure sensor is disclosed having a pressure sensing optical cavity. A temperature sensing optical cavity at the sensing head is used by an interrogator to correct a pressure signal for effects of temperature. The optical cavities may be, for example, Fabry Perot cavities in the sensor head.

Abstract: An optical pressure sensor is disclosed having a pressure sensing optical cavity. A temperature sensing optical cavity at the sensor head is used by an interrogator to correct a pressure signal for effects of temperature. The optical cavities may be, for example, Fabry Perot cavities in the sensor head.

Abstract: A transducer is disclosed for detecting a property of a fluid such as pressure, using a mechanical resonator having a resonant frequency dependent upon the fluid property. The transducer also has a temperature sensing optical cavity with an optical path difference which varies in correspondence with changes in temperature of the transducer.

Abstract: An optical sensor is described for distinguishing between liquids of different refractive index, through strength of interference caused by an optical cavity having an exposed optical boundary in contact with such liquids. The sensor may be used, for example, to distinguish between water and aviation fuel in an aircraft fuel tank.

Abstract: An optical sensor having one or more sensing interference elements is disclosed. A first detector function generates a coarse optical path difference signal for example using a discrete Fourier transform of a detected interference spectrum, and a second detector function generates a refined optical path difference signal using the coarse optical path difference signal and for example a cross correlation of the interference spectrum with one or more sets of periodic transfer functions.

Abstract: An optical pressure sensor is disclosed having a pressure sensing optical cavity. A temperature sensing optical cavity at the sensor head is used by an interrogator to correct a pressure signal for effects of temperature. The optical cavities may be, for example, Fabry Perot cavities in the sensor head.

Abstract: An integrated optical device comprising at least one optical waveguide (1) formed on a substrate, the waveguide (1) being of elongate form with an optical axis extending along its length, at least one interceptor trench (3, 4, 5 or 6) being provided in the substrate adjacent at least one side of the waveguide (1), the trench (3, 4, 5,6) presenting a surface to intercept stray light travelling in the substrate in a direction substantially parallel to the optical axis of the waveguide (1), said surface being angled with respect to the direction of travel of said stray light so as to alter the direction of travel of the stray light intercepted thereby.

Abstract: An A-VMUX comprises a AWG having N channel waveguides incorporating VOAs and receiving channel signals by way of a AR coating, and an output waveguide. An ordinary SOA is provided in the output waveguide for amplifying the multichannel output signal supplied to the optical fibre, and an auxiliary waveguide is provided for supplying a lasing signal to the AWG having a wavelength outside the main signal wavelength band in order to provide gain-clamping of the SOA. The auxiliary waveguide is provided with a highly reflective (HR) coating at the edge of the chip that forms a lasing cavity with the Bragg grating provided in the optical fibre. Furthermore an intra-cavity VOA is provided for attenuating the lasing signal. Such an arrangement uses the wavelength selecting function of the AWG to provide the required gain-clamping of the SOA with the Bragg grating being selected to match the wavelength of the auxiliary channel provided by the auxiliary waveguide.

Abstract: A planar waveguide module has integrally formed thereon a waveguide and, in sequence along the optical transmission path, a first LOA, a 90° polarisation rotator, a VOA and a second LOA. The LOAs and are gain-clamped SOAs having linear gain responses over the required wavelength range. In the absence of the polarisation rotator the PDGs of the LOAs would be added together to provide an overall PDG of approximately twice the PDG of a single LOA. However the inclusion of the polarisation rotator between the LOAs causes a substantial reduction in the overall PDG. If TE polarised light is supplied to the first LOA, the polarisation rotator will cause TM polarised light to be supplied to LOA, and accordingly the overall gain of the module will equal Gain(TE, LOA 3)+Gain(TM, LOA 7)−attenuation.

Abstract: An interferometer is integrated on an optical chip. The optical chip is formed on a layer of silicon separated from a substrate by a layer of insulating material. The optical chip includes an integrated fiber connector for connecting the optical chip to one or more optical fibers. The fiber connector includes a groove formed in the substrate for receiving an optical fiber and a waveguide for transmitting light to or from the fiber connector. The waveguide includes rib waveguides formed in the layer of silicon and at least one phase modulator for altering the phase of light traveling along one of the rib waveguides. This arrangement forms an interferometer in which light transmitted along different optical paths can be combined and the effective path length of at least one of the optical paths can be altered by the phase modulator.

Abstract: An optical system comprises two optical paths P1, P2, and an optical path changer for changing the optical length of the two optical paths. The optical path changer includes two phase modulators M1, M2 one coupled to each of the paths. A driving system is configured to apply power to the phase modulators to drive them in the same direction and to change the power applied to the phase modulators in opposite directions so as to change the length of each optical path in a different direction. As a result, the relationship between the changes in the power applied to the phase modulators and the resulting changes in the phase of light beams passing through the optical system becomes substantially linear.

Abstract: An integrated optical circuit for use in a fibre optic gyroscope which senses rotation rates by determining a phase shift due to the Sagnac Effect between light beams travelling around an optical fibre sensing loop (4) in opposite directions, the circuit being provided on a silicon-on-insulator chip comprising a layer of silicon separated from a substrate by an insulating layer, the circuit comprising: rib waveguides (11) formed in the silicon layer for receiving light from a light source (2) and transmitting light to a light detector (3), fibre optic connectors (9) in the form of grooves etched in the silicon layer for receiving the respective ends of the optical fibre sensing loop (4); rib waveguides (11) formed in the silicon layer for transmitting light to and from said fibre optic connectors (9) so as to direct light beams in opposite directions around the sensing loop (4) and receive light beams returning therefrom, phase determining means and (13,17,31) integrated in silicon layer for determining a pha