A system for interrogating sensors in a fiber optical sensor network includes groups of sensors. The sensors in one group operate at different wavelengths, and the sensors of other groups may have overlapping wavelengths. A light source generates a broadband light signal, input and output means for guides the broadband light to the fiber optical sensor network for illuminating the sensors and for coupling the light signal coming from the sensors of the fiber optical sensor network to the detection system, and a detection system detects the received light signal, during a detection integration time. The system is arranged for selecting pre-dominantly the received light coming from the different sensors of a selected group of sensors using a code-division multiplexing technique and simultaneously detecting sensors of the selected group of sensors using a wavelength-division multiplexing technique.

The photo-acoustic conversion based sound emitter device has a sound output surface for transmitting sound wave vibrations to a medium outside the device. An optical waveguide, is used to transmit light through an optical path within the device. First and second photo-acoustic conversion volumes, at different distances from the sound output surface, are used for transmitting sound generated in the first and second volume to the medium via the sound output surface, the optical path extending directly or indirectly successively through the first and second photo-acoustic conversion volume. The device comprises an intermediate volume separating the first and second photo-acoustic conversion volumes along the optical path, the intermediate volume having a lower light absorption coefficient than the first and second photo-acoustic conversion volumes; and/or the first and second photo-acoustic conversion volume have a different cross-section area size and/or shape with virtual planes perpendicular to the optical path; and/or the first and second photo-acoustic conversion volumes have different optical absorption coefficients, or a different optical wavelength dependence of these optical absorption coefficients.

An EHz ultrafast modulated pulse scanning laser and a distributed fiber sensing system. A plurality of phase-shift gratings are engraved on a doped fiber, the phase-shift gratings having different central window wavelengths and a wavelength interval between the adjacent central window wavelengths being a preset fixed value. When a pump light emitted by a pump laser source is coupled by a wavelength division multiplexer and enters the doped fiber, a single-mode narrow-linewidth laser light having multiple wavelengths with a wavelength interval being a preset fixed value can be generated, by using the phase-shift gratings graved on the doped fiber. The ultrafast modulation is completed by using a time-domain control method based on an EOM. An internally frequency converted pulse light formed by splicing pulse lights whose frequencies linearly increase is obtained, thus forming the EHz ultrafast modulation of a distributed feedback fiber laser. In this way, a coherence length of an output laser light is increased while a frequency of the laser light is remained.

The invention provides a dynamically swept tunable laser system and method for measuring sensor characteristics obtained from an array of optical sensors comprising means for dividing the total wavelength sweep of the laser into different regions in any particular order where each region contains single or multiple contiguous sweep segments and where each sweep segment is referenced by a start and a stop reference and can have different lengths compared to the other sweep segments. The sensor characteristics are determined from each region swept by the tunable laser. The invention provides for the tunable laser to be adapted to operate in a quasi-continuous mode to select segments in any order. The relative sweep rates of regions can be changed such that some regions can be swept more times than other regions.

A system for interrogating sensors in a fiber optical sensor network includes groups of sensors. The sensors in one group operate at different wavelengths, and the sensors of other groups may have overlapping wavelengths. A light source generates a broadband light signal, input and output means for guides the broadband light to the fiber optical sensor network for illuminating the sensors and for coupling the light signal coming from the sensors of the fiber optical sensor network to the detection system, and a detection system detects the received light signal, during a detection integration time. The system is arranged for selecting pre-dominantly the received light coming from the different sensors of a selected group of sensors using a code-division multiplexing technique and simultaneously detecting sensors of the selected group of sensors wavelength-division multiplexing technique.

A photonic device has a substrate with one or more optical resonators having a first resonant frequency response relative to temperature and a different second resonant frequency response relative to temperature. A first waveguide optically couples a first light beam having a first frequency to a first optical resonator and a second waveguide optically couples a second light beam having a second frequency to a second optical resonator. An optical shifter may shift an optical characteristic of the second light beam. A detector converts output light from the photonic device into an electric signal having a characteristic indicative of a physical condition, such as temperature, of the photonic device. In some cases, output light from the one or more optical resonators is combined and a temperature of the photonic device is determined from a beat frequency in the combined light. One or more multimode optical resonators may be used.

The present invention discloses a Fiber Bragg Grating demodulation device with a suppressed fluctuation at a variable ambient temperature and a demodulation method. The device comprises a broadband light source (1), an optical attenuator (2), a tunable F-P filter (3), a first optical fiber isolator (41), an erbium-doped optical fiber amplifier (5), an optical fiber first-stage beam splitter (6), a first optical fiber second-stage beam splitter (71), optical fiber circulators (8), FBG sensor arrays (9), a first photoelectric detector array (161), an optical fiber gas cell (10), a second optical fiber second-stage beam splitter (72), an optical fiber F-P etalon (11), a notch filter (12), an optical fiber assisted interferometer (13), a data acquisition card (17) and a processor (18).

A photonic device has a substrate with one or more optical resonators having a first resonant frequency response relative to temperature and a different second resonant frequency response relative to temperature. A first waveguide optically couples a first light beam having a first frequency to a first optical resonator and a second waveguide optically couples a second light beam having a second frequency to a second optical resonator. An optical shifter may shift an optical characteristic of the second light beam. A detector converts output light from the photonic device into an electric signal having a characteristic indicative of a physical condition, such as temperature, of the photonic device. In some cases, output light from the one or more optical resonators is combined and a temperature of the photonic device is determined from a beat frequency in the combined light. One or more multimode optical resonators may be used.

The present invention provides novel apparatus and methods for fast quantitative measurement of perturbation of optical fields transmitted, reflected and/or scattered along a length of an optical fibre. The present invention can be used for point sensors as well as distributed sensors or the combination of both. In particular this technique can be applied to distributed sensors while extending dramatically the speed and sensitivity to allow the detection of acoustic perturbations anywhere along a length of an optical fibre while achieving fine spatial resolution. The present invention offers unique advantages in a broad range of acoustic sensing and imaging applications. Typical uses are for monitoring oil and gas wells such as for distributed flow metering and/or imaging, seismic imaging, monitoring long cables and pipelines, imaging within large vessel as well as for security applications.

In order to enable an area suspected of having a communication abnormality to be identified from among a communication device and a communication path that constitute a communication system, this abnormality identification device is provided with: a first output unit which outputs first information that is information indicating the suitability of a transmission signal to be supplied to a communication channel; a second output unit which outputs second information that is information indicating the suitability of a reception signal corresponding to the transmission signal that has arrived via the communication channel; and a third output unit which outputs third information that is information indicating the suitability of a signal obtained by applying predetermined processing to the reception signal.