One or more spacers for installing an optical cable are disposed in a trench that extends along an axis. The optical cable includes one or more optical sensors. Each spacer includes a base configured to rest in a bottom of the trench. A first arm extends from the base. The first arm is adjacent to a first wall of the trench. An opposing second arm extends from the base. The second arm is adjacent to an opposing second wall of the trench. The optical cable is configured to extend along the axis.

A device for coupling a sensor to a fiber optic cable including at least one optical fiber, the device may include an activation unit couplable to a known coupling location along the fiber optic cable and configured to: receive an analog sensor output signal from the sensor and change one or more properties of at least one of: one or more optical wave propagating through the at least one optical fiber and the at least one optical fiber, with respect to the analog output signal, while maintaining at least a portion of a spectral content of the analog sensor output signal during at least a portion of time.

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. The method further comprises performing a measurement that characterizes the interrogation phasor; updating the parameters of the distributed back-reflection processing based on the measurement result such that an effect of fluctuations in the interrogation phasor on the measured response from the fiber is reduced; and applying distributed back-reflection processing to the receiver output signal. Finally, the method comprises extracting the response from the optical fiber from the distributed back-reflection processing output. A system for measuring a response from an optical fiber providing distributed back reflections is also disclosed.

An optical fiber characteristics measurement system includes: an optical fiber characteristics measurement device including: an emission port configured to emit probe light; and an incidence and emission port connected to one end of a measurement target optical fiber and configured to emit pump light, stimulated Brillouin scattered light generated within the measurement target optical fiber being incident on the incidence and emission port; a first optical fiber having one end connected to the emission port and configured to guide the probe light to another end of the measurement target optical fiber; and an optical isolator provided between another end of the first optical fiber and the another end of the measurement target optical fiber, and configured to cause the probe light guided by the first optical fiber to be incident on the another end of the measurement target optical fiber.

An optical fiber transducer usable in environments of extreme operating temperature features a stationary support, a movable body displaceable back and forth relative thereto, and an optical fiber connected between the support and the movable body. The fiber has a Fiber Bragg Grating in an intermediate region thereof between the support and movable body. To accommodate varying coefficients of thermal expansion (CTEs) among these components, one or more tubes close circumferentially around the fiber. Each tube has a CTE that is greater than that of the fiber, and less than that of the constituent material of the support and movable body. The fiber is bonded to an interior of the tube(s), while an exterior of the tube(s) is bonded to the support and movable body.

Aspects of the present disclosure describe distributed fiber optic sensing (DFOS) systems, methods, and structures that advantageously sense/monitor outdoor facilities and structures including outdoor cabinets containing fiber optic facilities in which the cabinet/fiber optic cable contained therein are configured to provide superior acoustic sensing. Further outdoor facilities and structures that are monitored include manhole structures. Superior DFOS/DAS monitoring results are obtained by employing a machine learning-based analysis method that employs a temporal relation network (TRN).

An apparatus has a chassis having a base. A first wall extends substantially perpendicularly from the base at a first edge of the base. The first wall is configured to be a first attachment point for an optical cable comprising one or more optical sensors. An opposing second wall extends substantially perpendicularly from the base at a second edge of the base. A mobile attachment point is configured to be a second attachment point for the optical cable. A spring is coupled to the second wall and the mobile attachment point. The spring is configured to provide a specified force as the mobile attachment point moves.

According to examples, an optical fiber-based sensing membrane may include at least one optical fiber, and a substrate. The at least one optical fiber may be integrated in the substrate. The optical fiber-based sensing membrane may include, based on a specified geometric pattern of the at least one optical fiber, an optical fiber-based sensing membrane layout. The substrate may include a thickness and a material property that are specified to ascertain, via the at least one optical fiber and based on the optical fiber-based sensing membrane layout, a thermal and/or a mechanical property associated with a device, or a radiation level associated with a device environment.

An apparatus includes one or more stamps configured to install an optical fiber on a surface of a structure. Each stamp includes a backing. A first adhesive is disposed on one or more first regions of the backing and is configured to provide a temporary bond between the optical fiber and the surface. A second adhesive is disposed on at least a second region of the backing and is configured to provide a substantially permanent bond between the optical fiber and the surface. A liner is removably adhered to the first adhesive.

A sensor device for measuring a temperature in a photovoltaic laminate structure and a sensor system comprising such a sensor device is provided. The sensor device includes a capillary for being embedded in the laminate structure between two layers thereof, a medium arranged within the capillary, and an optical fiber extending through the capillary and surrounded by the medium. At least a portion of the optical fiber has temperature-dependent transmission characteristics.