Testing Methods for Multimode Dual-Core Fiber Optic Patch Cords

Testing dual-core multimode fiber patch cords involves measuring insertion loss, return loss, and verifying polarity for each fiber using a calibrated light source, power meter, and reference cables.

Equipment Needed

Multimode LE

D light source (850 nm, optionally 1300 nm) for multimode fibers. Optical power meter calibrated to the same wavelength as the source. Reference patch cords of the same fiber type and size (50/125 or 62.

5/125) to set a 0 dB reference. Mating adapters compatible with the connectors on the patch cord. Cleaning supplies for connectors and adapters to prevent contamination.

Testing Procedure

Set up the reference: Connect a reference patch cord to the light source and set the power meter to read 0 dB. This establishes a baseline for loss measurement. Connect the patch cord under test: Use a mating adapter to connect one end of the dual-core patch cord to the reference cable and the other end to the power meter.

Measure insertion loss (IL): Record the power loss for each fiber individually. Since the patch cord is short, fiber attenuation is negligible, so the measurement primarily reflects connector quality. Reverse the patch cord: Test the opposite end to verify the second connector.

Polarity verification: For duplex or uniboot cords, ensure the transmit (Tx) and receive (Rx) channels are correctly aligned. Reverse polarity cords can be converted from TIA-568 A-B to A-A without tools if needed. Return loss (RL) and endface inspection: Use an optical loss test set (OLTS), OTDR, or endface metrology tools to check for reflections, scratches, pits, or contamination that could degrade performance.

Additional Considerations

Connector types: Ensure patch cord connectors match the equipment or use hybrid adapters if necessary. Fiber type compatibility: OM3 patch cords can be used on OM2 or OM4 cable plants, but matching fiber type is recommended for optimal performance. Documentation: Record IL, RL, and polarity results for quality assurance and troubleshooting.

Maintenance: Clean connectors before and after testing to maintain low loss and prevent damage. By following these steps, you can ensure that dual-core multimode patch cords meet performance standards, maintain signal integrity, and are ready for deployment in optical networks.