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OTDR: Measurement of “Unconnectorized” Optical Fiber Cables

OTDR: Measurement of “Unconnectorized” Optical Fiber Cables

When evaluating products in the manufacture of optical fiber cable, it is often necessary to measure fiber length and attenuation for an unprocessed fiber, which does not have a connector at either end. Since the Optical Time Domain Reflectometer (OTDR) port requires a connector, an unprocessed fiber cannot be connected directly to it. V-groove is a tool that can join a launch fiber, which has a connector on one end, to an unprocessed fiber. This allows it to be connected to the OTDR and measured.

V-groove

•A fiber coupling tool with V-shaped grooves cut to fit the thickness of the fiber.

•Two optical fibers lock along the groove.

•Index-matching gels are applied to the contact point to suppress reflection.

•A version is also available for multicore fibers (tape or ribbon fiber),

•Please note that it is not possible to mate fibers with different outer diameters. Outer diameters must be the same.

V-groove

If the fiber to be measured is short, or if a precise measurement is desired, use the launch fiber as a dummy fiber. The launch (dummy) fiber length should be longer than the dead zone at the near-end of the fiber. It must be long enough to be detected as an event.

By performing analysis with the “Dummy fiber setting” on the OTDR turned on, the V-groove position becomes [R] point and the far-end of the fiber becomes [E] point. Therefore, only the measured fiber portion (between [R] and [E]) excluding the launch fiber portion is analyzed.

nDummy Fibers setting for AQ 7280

•Press the [SETUP] , [F1: Detail],
[F3: Analysis Setup], and [Launch Fiber Setting]

•Select [Set on Distance]

•Enter a length of launch fiber in the “From Start” section.