Abstract: Provided is an optical communication system configured as an optical ring network including: a first optical communication device configured to transmit a first optical signal having a first wavelength in a first direction, and to transmit a second optical signal having a second wavelength in a second direction opposite to the first direction; and a second optical communication device configured to generate a first reflected signal by reflecting the first optical signal when the first optical signal is received, to generate a second reflected signal by reflecting the second optical signal when the second optical signal is received, and to transmit the first and second reflected signals to the first optical communication device, wherein the first optical communication device analyzes a connection state of the second optical communication device based on the first and second reflected signals.

Abstract: An optical test instrument, in combination with a removable connector cartridge is provided. A method of replacing a damaged or worn optic fiber interface is also provided. The optical test instrument has casing having a cartridge receiving cavity therein with an inner end provided with a test instrument optical port; and an outer end provided with a cartridge receiving opening. The connector cartridge is sized and configured to be inserted in the cartridge receiving cavity. The connector cartridge has a cartridge inner end for facing the test instrument optical port when in use, and a cartridge outer end for receiving an optic fiber from a device under test (DUT). The connector cartridge houses a fiber optic cable extending between the cartridge inner end and the cartridge outer end. The connector cartridge is removably connectable to the instrument casing to allow replacement of the connector cartridge when the cartridge outer end is worn or damaged.

Abstract: This disclosure describes inputting pulsated pump light in a fundamental mode or a first higher-order mode into one end of an optical fiber under test constructed by connecting two optical fibers in series; inputting probe light having an optical frequency difference within a Brillouin frequency shift range with respect to the pump light into the other end of the optical fiber under test in the fundamental mode or the first higher-order mode; measuring a Brillouin gain distribution related to a distance of transmitted light intensity of probe light output from the one end into which the pump light was input; and calculating each inter-modal coupling efficiency at the connection point of the optical fiber under test.

Abstract: Methods for estimating the Effective Modal Bandwidth (EMB) of laser optimized Multimode Fiber (MMF) at a specified wavelength, ?S, based on the measured EMB at a first reference measurement wavelength, ?M. In these methods the Differential Mode Delay (DMD) of a MMF is measured and the Effective Modal Bandwidth (EMB) is computed at a first measurement wavelength. By extracting signal features such as centroids, peak power, pulse widths, and skews, as described in this disclosure, the EMB can be estimated at a second specified wavelength with different degrees of accuracy. The first method estimates the EMB at the second specified wavelength based on measurements at the reference wavelength. The second method predicts if the EMB at the second specified wavelength is equal or greater than a specified bandwidth limit.

Abstract: An isolator based on a waveguide-based artificial dielectric medium is scalable to a range of desired terahertz frequencies, has non-reciprocal transmission and provides low insertion loss and high isolation at various tunable terahertz frequencies, far exceeding the performance of other terahertz isolators, and rivaling that of commercial optical isolators based on the Faraday effect. This approach offers a promising new route for polarization control of free-space terahertz beams in various instrumentation applications. Artificial dielectrics are man-made media that mimic properties of naturally occurring dielectric media, or even manifest properties that cannot generally occur in nature. A simple and effective strategy implements a polarizing-beam-splitter and a quarter wave plate to form a highly effective isolator. Performance of the device is believed to exceed that of any other experimentally demonstrated method for isolation of back-reflections for terahertz beams.

Abstract: A hybrid automated testing equipment (ATE) system can simultaneously test electrical and optical components of a device under test, such as an optical transceiver. The device under test can be a multilane optical transceiver that transmits different channels of data on different lanes. The hybrid ATE system can include one or more light sources and optical switches in an optical test lane selector to selectively test and calibrate each optical and electrical components of each lane of the device under test.

Abstract: A wavelength checker includes an optical waveguide chip. A known arrayed-waveguide diffraction grating is formed on the optical waveguide chip. The wavelength checker includes a light conversion unit made of a conversion material that converts infrared light into visible light. The light conversion unit is arranged on an output side of a plurality of first output waveguides of the optical waveguide chip to be capable of receiving light emitted from the plurality of first output waveguides. The light conversion unit is formed on a side surface of a support facing an output end surface of the optical waveguide chip. The support is fixed to a main board.

Abstract: An optical testing circuit on a wafer includes an optical input configured to receive an optical test signal and photodetectors configured to generate corresponding electrical signals in response to optical processing of the optical test signal through the optical testing circuit. The electrical signals are simultaneously sensed by a probe circuit and then processed. In one process, test data from the electrical signals is simultaneously generated at each step of a sweep in wavelength of the optical test signal and output in response to a step change. In another process, the electrical signals are sequentially selected and the sweep in wavelength of the optical test signal is performed for each selected electrical signal to generate the test data.

Abstract: A scanning probe microscope including a holder having at least one electric port, wherein the holder is configured to support a sample to be imaged. The scanning probe microscope further includes a probe and an actuator configured to move at least one of the holder and the probe up to three directions. The scanning probe microscope further includes a reflectometer configured to measure reflection and/or transmission coefficients at each of the at least one electric ports of the holder by feeding each of the at least one electric ports of the holder with electromagnetic wave signals.

Abstract: The disclosed systems and methods for characterizing an optical fiber in a dense wavelength division multiplexing (DWDM) optical link. The characterizing comprising: i) applying a power dither to data bearing optical signals propagating in the optical fiber, the power dither having a high-power level and a low-power level; ii) computing optical time-domain reflectometer (OTDR) traces corresponding to the high-power level and the low-power level of the power dither; iii) averaging the OTDR traces corresponding to the high-power level and the OTDR traces corresponding to the low-power level into average OTDR traces; computing a differential Stimulated Raman Scattering (SRS) gain from the OTDR traces; and iv) adjusting the average OTDR traces based on the differential SRS gain.

Abstract: An adjustable attenuation wrap plug for insertion into a signal port at an end product includes a housing with a protruding input prong and output prong, wherein a signal cable is coupled to the input prong and the output prong. The adjustable attenuation wrap plug further includes a ratchet mechanism at least partially disposed in the housing, wherein the ratchet mechanism is configurable to alter a shape of the signal cable.

Abstract: An optical cable includes an optical fiber having a fiber core and a fiber cladding, and an output coupling plug at an output coupling-side fiber end of the optical fiber. The output coupling plug comprises at least one cladding light sensor arranged behind the output coupling-side fiber end and configured to measure cladding light that exits frontally from the fiber cladding at the output coupling-side fiber end.

Abstract: In some examples, an optical time-domain reflectometer (OTDR) device may include a laser source to emit a plurality of laser beams. Each laser beam may include a different pulse width. A control unit may analyze, for each laser beam, a backscattered signal from a device under test (DUT). The control unit may generate, for each backscattered signal, a trace along the DUT. Further, the control unit may generate, based on an analysis of each trace along the DUT, a combined trace that identifies optical events detected along the DUT.

Abstract: Embodiments of the present disclosure relate to a display apparatus. The display apparatus includes: a display; a user interface; and a controller, configured to perform: in response to a user input, synchronizing menu content data set under a current source to other sources, so that the other sources can obtain the same display effect as that under the current source. Unnecessary repeated setting is avoided, and convenience is brought to users in use.

Abstract: A time of flight (TOF) assembly includes a laser light source, one or more photo detectors and a detection circuit. The one or more photo detectors are configured to receive light and convert the received light into an electric signal. The detection circuit is configured to send a turning-off control signal to turn off the laser light source in response to the electric signal indicating that a time length, in which the laser light source is in an effective working state within a first duration, is greater than a preset time length threshold value or the electric signal indicating that energy of light emitted from the laser light source within a second duration is greater than a preset energy threshold. The disclosure also provides a terminal device and a control method for a TOF assembly.

Abstract: In some examples, an optical time-domain reflectometer (OTDR)-based high reflective event measurement system may include an OTDR, and an N by M optical switch optically connected to the OTDR or disposed within the OTDR. The optical switch may include a variable attenuator mode and at least one optical fiber connected to at least one output port of the optical switch. At least one fiber optic reflector may be disposed at an end of the at least one optical fiber. A variable optical attenuator may reduce, for the at least one optical fiber including the at least one fiber optic reflector, an amplitude of reflective peaks.

Abstract: There is provided a method for measuring the PDL of a DUT as a function of the optical frequency ? within a spectral range, which uses a single wavelength scan over which the input-SOP varies in a continuous manner. The power transmission through the DUT, curve T(?), is measured during the scan and the PDL is derived from the sideband components of the power transmission curve T(?) that results from the continuously varying input-SOP. More specifically, the Discrete Fourier Transform (DFT) of the power transmission curve T(?) is calculated, wherein the DFT shows at least two sidebands. At least two sidebands are extracted and their inverse DFT calculated individually to obtain complex transmissions (?), =?J . . . J, where J is the number of sidebands on one side.

Abstract: Methods and systems for implementing a traditional computer vision algorithm as a neural network. The method includes: receiving a definition of the traditional computer vision algorithm that identifies a sequence of one or more traditional computer vision algorithm operations; mapping each of the one or more traditional computer vision algorithm operations to a set of one or more neural network primitives that is mathematically equivalent to that traditional computer vision algorithm operation; linking the one or more network primitives mapped to each traditional computer vision algorithm operation according to the sequence to form a neural network representing the traditional computer vision algorithm; and configuring hardware logic capable of implementing a neural network to implement the neural network that represents the traditional computer vision algorithm.

Abstract: In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. :A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

Abstract: Systems and methods include a method for overcoming optical time domain reflectometry (OTDR) dead zone limitations by using a few-mode fiber (FMF). Optical pulses are transmitted by a transmitter of an OTDR system through a mode MUX/DEMUX into an FMF. Light signals directed by the FMF in a backward direction through the mode MUX/DEMUX are received by the OTDR system through N single-mode fiber (SMF) ports corresponding to N modes in the FMF. Light signals from N?1 dead-zone-free SMF ports are collected by the OTDR system. Losses are measured and faults are located in the FMF based at least on the light signals.

Abstract: An OSS foreshortening detection system employing an interventional device (40) including a OSS sensor (20) having shape nodes for generating shape sensing data informative of a shape of OSS sensor (20). The system further employs a OSS foreshortening detection device (80) including a OSS shape controller (90) for reconstructing a shape of a portion/entirety of interventional device (40) derived from a generation of the shape sensing data by OSS sensor (20). Device (80) further includes a OSS foreshortening controller (100) for monitoring any foreshortening of the interventional device (40) within an image of the interventional device (40) including the OSS foreshortening controller (100) detecting a location of any occurrence of a foreshortening of the interventional device (40) within the image of interventional device (40) derived from the reconstruction of the shape of the portion/entirety of interventional device (40) by the OSS shape controller (90).

Abstract: Channel predictive behavior and fault analysis may be provided. A forward time value may be determined comprising a time a forward signal takes to travel from a transmitter over a channel to the receiver. Next, a reflected time value may be determined comprising a time a reflected signal takes to travel to the receiver. The reflected signal may be associated with the forward signal. A discontinuity may then be determined to exist on the channel based on the forward time value and the reflected time value. The reflected signal may be caused by the discontinuity and a high impedance or low impedance at the transmitter present after the forward signal is sent.

Abstract: A method for fabricating an integrated structure, using a fabrication system having a CMOS line and a photonics line, includes the steps of: in the photonics line, fabricating a first photonics component in a silicon wafer; transferring the wafer from the photonics line to the CMOS line; and in the CMOS line, fabricating a CMOS component in the silicon wafer. Additionally, a monolithic integrated structure includes a silicon wafer with a waveguide and a CMOS component formed therein, wherein the waveguide structure includes a ridge extending away from the upper surface of the silicon wafer. A monolithic integrated structure is also provided which has a photonics component and a CMOS component formed therein, the photonics component including a waveguide having a width of 0.5 ?m to 13 ?m.

Abstract: An OVNA system employing an array of reference delays to estimate distance-variant phase distortion in probe light during an optical-frequency sweep thereof. The estimated distance-variant phase distortion is then used to perform a phase correction for the digital electrical signals generated in response to the probe light being passed through a device under test (DUT) during the same optical-frequency sweep. Advantageously, the performed phase correction enables the OVNA system to provide a more-accurate determination of certain optical characteristics of the DUT than that achievable without such phase correction.

Abstract: The disclosure relates to a method, an optical receiver and an optical system for compensating, at an optical receiver, signal distortions induced in an optical carrier signal by a periodic copropagating optical signal, wherein the optical carrier signal and the copropagating signal copropagate at least in part of an optical system or network, by: receiving, at the optical receiver, the optical carrier signal, wherein the optical carrier signal is distorted by the copropagating signal; determining, at the optical receiver, a period of a periodic component of the distorted optical carrier signal; determining, at the optical receiver, a periodic distortion of the distorted optical carrier signal; and generating a compensation signal to correct the distorted optical carrier signal according to the determined periodic distortion.

Abstract: Methods of measuring an anomaly, any induced change in physical parameters such as strain, temperature, and so forth, in an optical fiber. One method may include launching a plurality of probe pulses from a probe source; recording a Brillouin scattering spectrum from a plurality of reflection signals generated in the optical fiber, responsive to the plurality of probe pulses; determining a relative motion between the optical fiber and the anomaly during the recording the Brillouin back-scattering spectrum; and dynamically adjusting the Brillouin back-scattering spectrum according to the relative motion, or performing an adjustment of the Brillouin back-scattering spectrum after acquisition of the Brillouin back-scattering spectrum.

Abstract: A photon source module includes a plurality of photon sources, wherein each photon source is configured to non-deterministically generate one or more non-entangled or entangled photons in response to receiving a trigger signal. When two or more photon sources simultaneously generate photons in response to a trigger signal, one photon of a first photon pair is directed to a photon processing system and one photon of a second photon pair is directed to a photon analyzer. During repetitive operation, the photon analyzer analyzes photons from each of the plurality of photon sources to determine characteristics of each photon source and can use that information to direct the highest quality photons to the photon processing system.

Abstract: A fiber includes M primary cores and N redundant cores, where M an integer is greater than two and N is an integer greater than one. Interferometric circuitry detects interferometric pattern data associated with the M primary cores and the N redundant cores when the optical fiber is placed into a sensing position. Data processing circuitry calculates a primary core fiber bend value for the M primary cores and a redundant core fiber bend value for the N redundant cores based on a predetermined geometry of the M primary cores and the N redundant cores in the fiber and detected interferometric pattern data associated with the M primary cores and the N redundant cores. The primary core fiber bend value and the redundant core fiber bend value are compared in a comparison. The detected data for the M primary cores is determined reliable or unreliable based on the comparison. A signal is generated in response to an unreliable determination.

Abstract: Aspects of the present disclosure describe distributed optical fiber sensing systems, methods, and structures that advantageously employ point sensors that send sensory data/information over an attached, distributed optical fiber sensor without using a separate network or communications facility.

Abstract: A system that includes an interference device including a reference arm on which a reflective surface is arranged, where the interference device produces, at each point of an imaging field when the sample is placed on a target arm of the interference device, interference between a reference wave and a target wave obtained by backscattering of incident light waves by means of a voxel of a slice of the sample at a given depth; an acquisition device suitable for acquiring, at a fixed path length difference between the target arm and the reference arm, a temporal series of N two-dimensional interferometric signals resulting from the interference produced at each point of the imaging field; and a processing unit that calculates an image representing temporal variations in intensity between said N two-dimensional interferometric signals.

Abstract: Fiber optic terminals having at least one loopback assembly comprising a loopback optical fiber providing optical communication between a first output connection port and a second output connection port of the terminal along with fiber optic networks using the terminals are disclosed. The loopback optical fiber is terminated with a first optical connector and a second optical connector. The first optical connector is attached to the first output connection port of the terminal and the second optical connector of the loopback assembly attached to the second output connection port of the terminal, thereby allowing the network operator to send a test signal to the terminal and receive a return signal when the terminal is installed in a fiber optic network.

Abstract: A Raman sensor includes a light source assembly having a plurality of light sources configured to emit light to a plurality of skin points of skin, each of the plurality of skin points having a predetermined separation distance from a light collection region of the skin from which Raman scattered light is collected; a light collector configured to collect the Raman scattered light from the light collection region of the skin; and a detector configured to detect the collected Raman scattered light.

Abstract: In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

Abstract: In some examples, automatic OTDR-based testing may include determining, based on analysis of a signal that is received from a DUT that is to be monitored, whether the DUT is optically connected. Based on a determination that the DUT is optically connected, a measurement associated with the DUT may be performed.

Abstract: In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

Abstract: A method for measuring a response from an optical fiber providing distributed back reflections using a system comprising an optical source comprising a laser, an optical receiver and a processing unit is disclosed. The method comprises establishing initial parameters of a distributed back-reflection processing. The method also comprises generating an interrogation signal and an optical local oscillator using the optical source, the interrogation signal being represented by an interrogation phasor and the optical local oscillator being represented by a local oscillator phasor; transmitting the interrogation signal into the optical fiber; and mixing the optical local oscillator with reflected light from the optical fiber and detecting a mixing product with the optical receiver to achieve a receiver output signal.

Abstract: There is provided a test method and system for characterizing an optical fiber link. At least one OTDR acquisition or at least one OLTS acquisition is performed on the optical fiber link. From the acquisition, a value of an excess insertion loss and/or an excess optical return loss associated with the optical fiber link under test is derived, i.e. in excess of a nominal value associated with a hypothetical optical fiber link having a length corresponding to the total length of the optical fiber link under test. A rating value (e.g., as a five-star rating) or a binary pass/fail value associated with the optical fiber link under test can then be derived and displayed.

Abstract: The concepts and technologies disclosed herein are directed to quantum tampering threat management. According to one aspect of the concepts and technologies disclosed herein, a quantum security manager (“Q-SM”) can monitor a plurality of quantum channels for tampering. The Q-SM can detect tampering on a quantum channel of the plurality of quantum channels. The Q-SM can provide tampering monitoring statistics to a software-defined network (“SDN”) that, in turn, notifies a quantum security operations center (“Q-SOC”) about the tampering on the quantum channel. The Q-SM can receive threat mitigation instructions from the Q-SOC. The threat mitigation instructions can instruct the Q-SM how to counter the tampering on the quantum channel. The Q-SM can perform one or more actions in accordance with the threat mitigation instructions to counter the tampering on the quantum channel.

Abstract: A variable-frequency light source is configured to emit a light beam and modulate a frequency of the light beam. A fiber optic cable is attached to the variable frequency light source. The fiber optic cable is configured to receive the light beam at an inlet and pass the light beam to an exit. Multiple optical detectors are attached to the fiber optic cable. Each of the optical detectors is configured to detect a specified frequency of light that is backscattered through the fiber optic cable. An actuation mechanism is attached to the fiber optic cable. The actuation mechanism is configured to deform the fiber optic cable in response to a stimulus.

Abstract: Aspects of the present disclosure describe a method for estimating mode field distribution in optical fibers from guided acoustic-wave Brillouin scattering wherein light for which the optical mode-field distribution is determined remains in the optical fibers and the distribution is made for light inside the fiber, and not at a fiber/air interface or other perturbation points to the fiber resulting in a more accurate representation of the optical mode-field distribution in the fiber. Since light is always in the fiber during the determination, no complicated fiber preparation steps or procedures are required and the mode-field distribution is determined as an average distribution along the length of the fiber under test.

Abstract: Aspects of the present disclosure describe physical layer security in optical telecommunications networks wherein a filtering-based physical security is provided by a wavelength tunable distributed fiber optical sensing (DFOS) system operating simultaneously on the telecommunications network.

Abstract: A test apparatus has at least one optical source, a high-speed photodetector, a microcontroller or processor, and electrical circuitry to power and drive the optical source, high-speed photodetector, and microcontroller or processor. The apparatus measures the frequency response and optical path length of a multimode optical fiber under test, utilizes a reference VCSEL spatial spectral launch condition and modal-chromatic dispersion interaction data to estimate the channels total modal-chromatic bandwidth of the fiber under test, and computes and presents the estimated maximum data rate the fiber under test can support.

Abstract: Provided is a spectroscopic analysis apparatus including: an optical probe; and a spectroscopic analysis portion to which the optical probe is attached. The optical probe includes an optical fiber that guides illumination light coming from a light source and signal light coming from an observation target and an optical member that is disposed at least at a distal end of the optical fiber. The spectroscopic analysis portion includes an information separation portion that generates wavelength dependent characteristics by optically dispersing the signal light and that separates, from information about the signal light, information about first return light returning from the optical member and information about second return light returning from the optical fiber, a problem determining portion that determines a problem occurring at the optical probe based on the separated first return light and second return light, and a notification portion that notifies information about the determined problem.

Abstract: In some examples, high speed bidirectional OTDR-based testing may include transmitting data from a first end of a device under test (DUT) towards an optical time-domain reflectometer (OTDR) that is operatively connected to a second opposite end of the DUT. Further data that is transmitted by the OTDR may be received from the second opposite end of the DUT towards the first end of the DUT. Based on an amplitude of the further data, a direction of receiving of the further data may be adjusted towards a first receiver or towards a second receiver.

Abstract: Systems and methods for implicit chemical resolution of vacuum gas oils and fit quality determination are disclosed. The systems and methods include utilizing an FT-IR spectrum of an unknown VGO composition, and a database of FT-IR spectra of known VGO compositions, to determine a model of composition for the unknown VGO composition. Additionally, the fit quality for the model of composition is determined by performing a partial least squares analysis on specific spectral regions of interest in the FT-IR spectrum of the unknown VGO composition.

Abstract: An optical fiber loss measurement device includes a unit configured to input pump light at a first frequency in a predetermined mode to a measurement target optical fiber in which a plurality of modes propagate from a first end, and input probe light at a second frequency to which a Brillouin frequency shift is applied to a second end, a Brillouin gain acquisition unit configured to measure an intensity of light output from the first end to acquire Brillouin gains in a longitudinal direction of the measurement target optical fiber using a BOTDA method, and a unit configured to measure a loss in the predetermined mode of the measurement target optical fiber, and the probe light is in a mode in which an electric field distribution in a cross section of the measurement target optical fiber is axisymmetric.

Abstract: The present disclosure relates generally to evaluating thermal properties of building surfaces. The present disclosure relates more particularly to a method of evaluating insulation in a cavity in a building surface. The method includes obtaining an infrared image of a first area of the building surface that covers the cavity, where the infrared image includes an array of digital pixel values. The infrared image is partitioned into a plurality of regions based on the digital pixel values. A shape of a first identified region is determined using a shape analysis algorithm and whether the first identified region corresponds to a first insulation void is recognized based on the determined shape of the first identified region.

Abstract: Bend information computation apparatus includes: an input unit having detected light quantity information representing a relation between a wavelength in a predetermined wavelength band and a light quantity, the detected light quantity information being acquired using a light guide having at least one light absorber for changing a light quantity of light transmitted through the light guide according to a bent state of the light absorber to detect a light quantity after a change; and an arithmetic operator for computing bend information representing a bend direction and a bend magnitude of each light absorber based on the detected light quantity information, an absorption spectrum of each light absorber, a bend coefficient of each light absorber that varies according to a bend direction and a bend magnitude of each light absorber, and a unique characteristic value of each light absorber including a value for a correction relating to the bend coefficient.

Abstract: An optical fiber characteristic measurement apparatus (1) includes: a light source (11) configured to output a laser beam of which frequency is modulated; an incident part (12, 13, 14, and 15) configured to make the laser beam output from the light source be incident from one end and another end of an optical fiber (FUT) as continuous light (L1) and pulsed light (L2), respectively; a light detector (16) configured to detect light projected from the optical fiber and output a detection signal (D1); and a detector (17 and 18a) configured to detect, in a first period (T1) in which scattering light based on the continuous light and the pulsed light is projected from the optical fiber and a second period (T2) shorter than the first period, in which the scattering light is not projected from the optical fiber, the scattering light based on integrated values acquired by integrating the detection signal for a predetermined time.

Abstract: The various embodiments described here comprise an OFDR system and technique that may be used for inference of strain or temperature over a large dynamic range using a narrow wavelength range. Embodiments of the sensor fiber may be composed of one or more multi-spectral-feature sensors, each sensor exhibiting several spectral features that together offer coverage over a wavelength range corresponding to the desired system strain and or temperature dynamic range.