An adjustable wide-spectrum wavelength-insensitive directional coupler, comprising a substrate (100). A first-stage directional coupling structure (1), a phase-shifting structure (2), and a second-stage directional coupling structure (3) are sequentially connected and disposed on the substrate (100). The phase-shifting structure (2) comprises a phase-shifting curved waveguide, a phase-shifting straight waveguide (22), and a third modulation component (26), wherein the third modulation component (26) is disposed on the phase-shifting curved waveguide. One end of the phase-shifting curved waveguide is connected to an output end of a directional coupled waveguide I (16) of the first-stage directional coupling structure (1), and the other end of the phase-shifting curved waveguide is connected to an input end of a directional coupled waveguide III (30) of the second-stage directional coupling structure (3). One end of the phase-shifting straight waveguide (22) is connected to an output end of a directional coupled waveguide II (17) of the first-stage directional coupling structure (1), and the other end of the phase-shifting straight waveguide (22) is connected to an input end of a directional coupled waveguide IV (31) of the second-stage directional coupling structure (3). The adjustable wide-spectrum wavelength-insensitive directional coupler achieves wide-spectrum wavelength-insensitivity, a wide spectrum of splitting-ratio adjustment and low loss, and is of a compact size for easy integration with other devices.

A loop back connector and methods for testing lines in a fiber optic network are disclosed. The loop back connector includes a ferrule having an interface side constructed for optical connection to a multifiber optical cable. The loop back connector also includes first and second optical loop back paths, each having first and second terminal ends positioned at the interface side. The terminal ends of each loop back path are adapted to be aligned to fibers in the multifiber optical cable. The method includes injecting a signal on a first optical path at a first location, looping back the signal at a second location onto a second optical path, and receiving the signal on the second optical path at the first location.

An adjustable wide-spectrum wavelength-insensitive directional coupler, comprising a substrate (100). A first-stage directional coupling structure (1), a phase-shifting structure (2), and a second-stage directional coupling structure (3) are sequentially connected and disposed on the substrate (100). The phase-shifting structure (2) comprises a phase-shifting curved waveguide, a phase-shifting straight waveguide (22), and a third modulation component (26), wherein the third modulation component (26) is disposed on the phase-shifting curved waveguide. One end of the phase-shifting curved waveguide is connected to an output end of a directional coupled waveguide I (16) of the first-stage directional coupling structure (1), and the other end of the phase-shifting curved waveguide is connected to an input end of a directional coupled waveguide III (30) of the second-stage directional coupling structure (3). One end of the phase-shifting straight waveguide (22) is connected to an output end of a directional coupled waveguide II (17) of the first-stage directional coupling structure (1), and the other end of the phase-shifting straight waveguide (22) is connected to an input end of a directional coupled waveguide IV (31) of the second-stage directional coupling structure (3). The adjustable wide-spectrum wavelength-insensitive directional coupler achieves wide-spectrum wavelength-insensitivity, a wide spectrum of splitting-ratio adjustment and low loss, and is of a compact size for easy integration with other devices.

An optical loopback member attaches to a counterpart optical connector to face a plurality of optical fibers of the counterpart optical connector that includes a first input optical fiber, second input optical fiber, first output optical fiber, and second output optical fiber. The optical loopback member includes a first reflector including: a first output light reflection surface that reflects a first output light, outputted in a first direction, from the first output optical fiber; and a first input light reflection surface that reflects light reflected by the first output light reflection surface and directs the reflected light to the first input optical fiber arranged in a second direction with respect to the first output optical fiber. The second direction is perpendicular to the first direction.

The loopback apparatus disclosed herein is used with an optical fiber system having an optical fiber cable. The loopback apparatus includes an optical fiber having input and output ends and an output optical fiber having input and output ends. The loopback apparatus also includes an optical system that defines an optical path and that is configured to optically couple the output end of the input optical fiber with the input end of the output optical fiber over the optical path. The loopback apparatus also includes a thin-film filter disposed in the optical path and configured to provide a select amount of attenuation for light traveling over the optical path. The loopback apparatus can be plugged into and unplugged from the optical fiber cable. Loopback methods for measuring the performance of the optical fiber system using the loopback apparatus are also disclosed.

Purging of fiber optic conduits in subterranean wells. A downhole optical sensing system includes an optical line, at least two tubular conduits, one conduit being positioned within the other conduit, and the optical line being positioned within at least one of the conduits, and a purging medium flowed in one direction through one conduit, and flowed in an opposite direction between the conduits. A method of purging a downhole optical sensing system includes the steps of: installing at least two conduits and an optical line in a well as part of the sensing system, one conduit being positioned within the other conduit, and the optical line being positioned within at least one of the conduits; and flowing a purging medium through the conduits in the well, so that the purging medium flows in one direction through one conduit and in an opposite direction between the conduits.

The loopback apparatus disclosed herein is used with an optical fiber system having an optical fiber cable. The loopback apparatus includes an optical fiber having input and output ends and an output optical fiber having input and output ends. The loopback apparatus also includes an optical system that defines an optical path and that is configured to optically couple the output end of the input optical fiber with the input end of the output optical fiber over the optical path. The loopback apparatus also includes a thin-film filter disposed in the optical path and configured to provide a select amount of attenuation for light traveling over the optical path. The loopback apparatus can be plugged into and unplugged from the optical fiber cable. Loopback methods for measuring the performance of the optical fiber system using the loopback apparatus are also disclosed.

A connector for a traceable cable having a tracing optical fiber, and a cable assembly having the same. The connector includes a connector housing and a light pipe positioned at least partially within the connector housing. The light pipe has at least one tracing optical fiber interface configured to be optically coupled to the tracing optical fiber. The light pipe also has at least one tracer light interface optically accessible from outside of the connector housing. The light pipe defines an optical path configured to direct tracer light from the at least one tracing optical fiber interface to the at least one tracer light interface. The at least one tracer light interface is configured to receive and emit the tracer light directed by the optical path.

A multi-tool for fiber optic applications is disclosed. In one embodiment, the multi-tool includes a male fiber loopback plug. The multi-tool further includes a fiber coupler having a first end and a second end. The first end of the fiber coupler is able to receive the male fiber loopback plug when the multi-tool is in a closed position. Also, the first end of the fiber coupler is able to receive a loose fiber cable end when the multi-tool is in an open position. The multi-tool also includes an end cap which can be removably coupled to the second end of the fiber coupler. The end cap and the fiber coupler cooperatively provide a protective housing for a fiber cable end when the end cap is removably coupled to the second end of the fiber coupler and the fiber cable end is inserted into the first end of the fiber coupler. Further, the male fiber loopback plug and the fiber coupler collectively make a female fiber loopback plug when the male fiber loopback plug is in a closed position and the end cap is removed from the second end of the fiber coupler. Also, a dust-resistant housing protectively encloses the male fiber loopback plug, the fiber coupler, and the end cap such that the multi-tool is protected from dust intrusion when the male fiber loopback plug is in the closed position and the cap is coupled to the second end of the fiber coupler.

A connector for a traceable cable having a tracing optical fiber, and a cable assembly having the same. The connector includes a connector housing and a light pipe positioned at least partially within the connector housing. The light pipe has at least one tracing optical fiber interface configured to be optically coupled to the tracing optical fiber. The light pipe also has at least one tracer light interface optically accessible from outside of the connector housing. The light pipe defines an optical path configured to direct tracer light from the at least one tracing optical fiber interface to the at least one tracer light interface. The at least one tracer light interface is configured to receive and emit the tracer light directed by the optical path.