An optical fiber sensing system according to the present disclosure includes: an optical fiber network (10) configured to detect first sensing information related to a first monitoring target and second sensing information related to a second monitoring target; a reception unit (21) configured to receive an optical signal from the optical fiber network (10); a specification unit (22) configured to specify a first monitoring target based on first sensing information superimposed on the optical signal and specify a second monitoring target based on second sensing information superimposed on the optical signal, and a provision unit (23) configured to provide information related to the first monitoring target and information related to the second monitoring target specified by the specification unit (22) for a service providing destination.

One embodiment described herein provides a system for distributed fiber sensing. The system can include a plurality of network elements (NEs) in an optical transport network (OTN) and a control-and-management module coupled to the NEs. A respective network element (NE) can include a first wavelength coupler configured to separate an optical supervisory channel (OSC) signal from a data-carrying signal received from a fiber span, a polarization-measurement unit configured to perform a polarization measurement on the OSC signal, and a transmitter configured to transmit an outcome of the polarization measurement to the control-and-management module, thereby facilitating distributed fiber sensing based on the outcome of the polarization measurement.

The invention relates to a system and method for detecting vibrations on the periphery of an optical fibre, which is divided into five subsystems that are connected together. First, a light-source subsystem (6) generates light, which is transmitted through an optical fibre subsystem (2). Then, speckle interference patterns generated in the optical fibre are read using a CMOS micro camera subsystem (5). Subsequently, the information is analysed by a processing subsystem (7), producing an alarm signal that is notified to the outside by means of a communications subsystem (1).

One embodiment described herein provides a system for distributed fiber sensing. The system can include a plurality of network elements (NEs) in an optical transport network (OTN) and a control-and-management module coupled to the NEs. A respective network element (NE) can include a first wavelength coupler configured to separate an optical supervisory channel (OSC) signal from a data-carrying signal received from a fiber span, a polarization-measurement unit configured to perform a polarization measurement on the OSC signal, and a transmitter configured to transmit an outcome of the polarization measurement to the control-and-management module, thereby facilitating distributed fiber sensing based on the outcome of the polarization measurement.

An apparatus and method for detecting composite material damage due to impact by using distributed optical fiber are disclosed. In the apparatus and method for detecting composite material damage due to impact by using distributed optical fiber, the position and level of damage occurring in a composite material due to low-velocity impact can be effectively and economically detected by measuring the residual strain of optical fiber distributed on the surface of the composite material or inside the composite material. In the apparatus and method for detecting composite material damage due to impact by using distributed optical fiber, there is no need to always operate a sensor in real time, so that detection errors due to temporary failures, malfunctions, etc. of the sensor, as well as a problem of constantly supplying power to the sensor, can be essentially removed.

An optical fiber changes a polarization state of a propagating light when at least one of a vibration and a displacement occurs. An optical transmitter inputs a first wavelength light to the optical fiber via a separator, and an optical transmitter inputs a second wavelength light to the optical fiber via a separator. The first and second wavelength lights propagated through the optical fiber in mutually opposite directions are respectively received by optical receivers (13 and 12) via the separators (18 and 17), and a fluctuation of a polarization is detected in polarization fluctuation detectors (16 and 15). A data processing device collects data indicating the fluctuation of the polarization detected by the polarization fluctuation detector and data indicating the fluctuation of the polarization detected by the polarization fluctuation detector.

An optical fiber sensor includes a first single mode fiber, a second single mode fiber, and a multimode fiber positioned between, and coupled to, the first single mode fiber and the second single mode fiber. The multimode fiber includes a graded-index core with an outer diameter between about 35 m and about 45 m. A numerical aperture of the core is between about 0.15 and about 0.25. The multimode fiber includes a cladding with an outer diameter between about 70 m and about 90 m. A coupling strength of an LP.sub.01 mode of the first single mode fiber to each of an LP.sub.02 mode and an LP.sub.03 mode of the multimode fiber is at least about 0.25.

An apparatus and method for detecting composite material damage due to impact by using distributed optical fiber are disclosed. In the apparatus and method for detecting composite material damage due to impact by using distributed optical fiber, the position and level of damage occurring in a composite material due to low-velocity impact can be effectively and economically detected by measuring the residual strain of optical fiber distributed on the surface of the composite material or inside the composite material. In the apparatus and method for detecting composite material damage due to impact by using distributed optical fiber, there is no need to always operate a sensor in real time, so that detection errors due to temporary failures, malfunctions, etc. of the sensor, as well as a problem of constantly supplying power to the sensor, can be essentially removed.

An optical fiber sensor includes a first single mode fiber, a second single mode fiber, and a multimode fiber positioned between, and coupled to, the first single mode fiber and the second single mode fiber. The multimode fiber includes a graded-index core with an outer diameter between about 35 m and about 45 m. A numerical aperture of the core is between about 0.15 and about 0.25. The multimode fiber includes a cladding with an outer diameter between about 70 m and about 90 m. A coupling strength of an LP.sub.01 mode of the first single mode fiber to each of an LP.sub.02 mode and an LP.sub.03 mode of the multimode fiber is at least about 0.25.

A deformation sensing apparatus comprises a propagation channel, a transmitter coupled to a first end of the propagation channel, a receiver coupled to a second end of the propagation channel, and a controller. The propagation channel is deformable and the controller instructs the transmitter to transmit a signal, instructs the receiver to capture one or more measurements of the transmitted signal, and determines a bend in the propagation channel based on the one or more measurements. In one embodiment, the transmitter is a light source, the propagation channel is an optical fiber, and the receiver is a photodiode. The propagation channel is made of a material that has a variation in a refractive index responsive to applied mechanical stress. The deformation sensing apparatus may also include a polarizer positioned between the transmitter and the propagation channel and a wave plate positioned between the propagation channel and the receiver.