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.

A process including the following steps: injecting in an optical fiber a first optical pump at a first optical frequency that evolves in time or not, and a second optical pump at a second optical frequency that evolves in time or not, the first optical frequency and the second optical frequency being different at each given time; a first detection of a first Rayleigh backscattered signal at the first optical frequency from the optical fiber, a second detection, separated from the first detection, of a second Rayleigh backscattered signal at the second optical frequency from the optical fiber; and analyzing the detected first Rayleigh backscattered signal and the detected second Rayleigh backscattered signal.

Apparatuses and methods for optical code-delay reflectometry (OCoDR) are disclosed. An apparatus includes a modulator, a receiver, and control circuitry. The modulator is configured to receive incident electromagnetic (EM) radiation at a substantially fixed frequency generated by one or more EM radiation sources. The incident EM radiation includes continuous-wave EM radiation. The modulator is configured to impart a sequence onto an amplitude, a phase, or both of the incident EM radiation to generate modulated EM radiation. The modulated EM radiation includes continuous-wave EM radiation. The receiver is configured to receive reference EM radiation. The receiver is also configured to receive reflected EM radiation from an optical system responsive to the modulated EM radiation and generate interfered EM radiation responsive to the reference EM radiation and the reflected EM radiation. The receiver is further configured to generate a continuous interferogram responsive to the interfered EM radiation.

A system includes at least one waveguide with optical interaction portions that represent a sequence of reference symbols based on the order of the optical interaction portions in the at least one waveguide. At least one light source sends photons of one or more predetermined wavelengths into the at least one waveguide representing a string of query symbols. A detector detects photons received from the at least one waveguide that result from optical interactions between photons sent into the at least one waveguide and one or more corresponding optical interaction portions with an interaction between photons and an optical interaction portion indicating a match between a query symbol and a reference symbol. An analyzer determines one or more respective relative locations of the one or more corresponding optical interaction portions indicating one or more relative locations of the string of query symbols in the reference sequence.

A transmitter generates a first electrical signal comprising a first low-frequency signal, an empty period, and a pump pulse having a first frequency; and a second electrical signal comprising a second low-frequency signal and at least two probe pulses, each probe pulse having a second frequency that differs from the first frequency. The transmitter modulates first and second optical subcarriers having different polarizations using the first and second electrical signals, respectively. The transmitter generates an optical signal from the first and second optical subcarriers, wherein the first and second low-frequency signals overlap in time, wherein the empty period overlaps in time with one of the probe pulses, and wherein the pump pulse overlaps in time with another one of the probe pulses. The optical signal is detected at a receiver over an optical link, and the receiver uses the optical signal to estimate nonlinear phase shift in the optical link.

An Optical Time Domain Reflectomeler (OTDR) tests an optical fiber by generating, transmitting, and receiving light signals from an optical fiber. The OTDR generates light signals having different characteristics and stitches these light signals into an OTDR trace. Backscatter and properties such as dynamic range effect the quality of the OTDR trace.

There is provided an OTDR receive device and an OTDR system comprising an OTDR receive device wherein the OTDR unit and the OTDR receive device are to be connected at opposite ends of an optical fiber link under test. The OTDR receive device comprises means for the OTDR system to detect an established connectivity between the OTDR unit and the OTDR receive device via the optical fiber link under test and a status indicator to notify a user of the receive device of the connectivity status and optionally an OTDR measurement status. Connectivity detection allows to check for continuity between the OTDR unit and the OTDR receive device before launching an OTDR measurement. A user of the OTDR unit does not need to communicate with the user of the OTDR receive device to know when to start the acquisition.

A method for determining the position of an irregularity in an optical transmission fiber using an optical time domain reflectometer, the method comprising the steps of emitting a succession of sampling light pulses into the optical transmission fiber, detecting reflected light pulses resulting from the reflection of the sampling light pulses at the irregularity in the optical transmission fiber and generating corresponding time-dependent detection signals, wherein different delays are associated with detection signals corresponding to different sampling light pulses, obtaining a combined signal from the detection signals, and analyzing the combined signal for determining the position of the irregularity in the optical transmission fiber with respect to the optical time domain reflectometer, wherein the combined signal corresponds to a superposition of the detection signals.

An object of the present invention is to provide an optical pulse test apparatus that can test an optical fiber cable at once in a short period of time. The optical pulse test apparatus according to the present invention includes: an optical pulse signal generation unit 11 that emits an optical pulse with a width that is n times as large as a pulse width T corresponding to desired spatial resolution; a light reception unit 12 that receives reflected light and back-scattered light from n FUTs; an optical path control unit 13 that switches paths connected to the n FUTs are connected at an interval T, inject the optical pulse, as a test optical pulse having the pulse width T, sequentially into the paths, then switches the paths at an interval ts that is shorter than the time period T, and emit the reflected light and the back-scattered light from the n FUTs sequentially onto the light reception unit 12 at an interval n×ts; and an arithmetic processing unit 14 that divides the electrical signal output from the light reception unit 12, with an interval equal to the interval ts at which switching the paths is performed, into discrete signals respectively corresponding to the FUTs, and calculates the reflectance distributions of the reflected light and the back-scattered light of the respective FUTs.

An optical sensing system for detecting fiber events along an optical cable under test (CUT) having forward and feedback fibers and multiple pairs of optical couplers interconnected along the forward and feedback fibers in a ladder topology. An optical transmitter generates an optical probing signal for a forward fiber, wherein the couplers along the forward fiber provide tapped portions of the probing signal to the couplers along a feedback fiber to form a combined optical feedback signal in the feedback fiber. A reference coupler is connected between the transmitter and the forward fiber to tap an optical reference signal from the probing signal, and a feedback coupler is connected to combine the reference signal and the feedback signal. An optical receiver receives and processes the combined reference and feedback signals from the feedback coupler to detect fiber events along the CUT.