MTP Loopback Cable

The MTP Loopback Cable is a factory-assembled multi-fiber optical assembly that provides a defined optical return path through an MTP/MPO interface. It routes transmitted optical channels back to designated receive channels within the same interface for transceiver verification, switch-port testing, equipment diagnostics, and optical test procedures.

Specify the MTP loopback according to the target test interface. The required configuration should be confirmed before production based on the interface, connector mating, channel mapping, and optical test condition.

Match the Fiber Count to the Interface: Select the fiber count according to the active optical channels and connector configuration of the interface under test.

Match the Fiber Type to the Optical Interface: Match the fiber type to the optical mode specified for the target transceiver, equipment, or test fixture.

Confirm MTP/MPO Connector Gender: Confirm the required connector gender from the mating interface; male connectors are pinned, while female connectors are unpinned.

Confirm the Tx-to-Rx Mapping: Confirm the required Tx-to-Rx channel relationship before ordering, particularly for application-specific test configurations.

Check the Optical Test Condition: Confirm whether the test requires a direct or attenuated loopback and specify the required receive-power condition where applicable.

A loopback configuration is defined not only by fiber count, but also by how the transmitted channels are returned to the intended receive channels.

Direct Loopback: A direct loopback returns the transmitted signal without intentional added attenuation when the resulting receive power meets the test requirement.

Attenuated Loopback: An attenuated configuration introduces a specified additional optical loss when the test requires lower receive power.

Attenuation Specification: Specify the required attenuation or target receiver condition so the optical configuration can be confirmed before production.

MTP loopback assemblies are checked against the confirmed production specification before shipment, covering connector geometry, end-face condition, optical performance, and defined Tx-to-Rx routing.

Connector & End-Face Control: 3D interferometer inspection is used to check MTP/MPO connector geometry, including fiber height, apex offset, and radius of curvature, while connector end faces are inspected for contamination and visible defects.

Optical & Mapping Verification: Each assembly is individually tested for insertion loss and return loss according to the specified configuration and test wavelength, while defined Tx-to-Rx routing is checked against the confirmed production mapping.

Test Records: Serialized test records can be provided for individual assemblies, including applicable optical test data and inspection results for product qualification and incoming inspection.

Custom MTP loopback cables are configured against the customer's equipment or test-fixture requirements.

Interface Reference
Provide the target equipment, transceiver, or test-fixture interface so the required connector and assembly configuration can be reviewed before production.

Mapping Reference
For non-standard loopbacks, provide a port map, fiber-position diagram, or Tx-to-Rx wiring specification.

Optical Requirement
Provide the required attenuation or target receiver condition when controlled optical power is part of the test specification.

Production Reference
Provide the required cable length, quantity, identification, and packaging requirements for quotation and production.
For application-specific configurations, DIMI reviews the supplied interface, mapping, and test requirements before production so the manufacturing specification can be confirmed against the requested assembly.