How to check if the fiber optic standard meets OM4

To verify that a fiber optic cable meets the OM4 standard, you need to test its effective modal bandwidth (EMB), insertion loss, and ensure it is a 50 µm laser-optimized multimode fiber. Key OM4 SpecificationsOM4 is a laser-optimized 50 µm multimode fiber designed for high-speed data transmission. Its main characteristics include: Effective Modal Bandwidth (EMB): 4700 MHz·km at 850 nm wavelength, which is higher than OM3 (2000 MHz·km) and allows longer transmission distances for 10G, 40G, and 100G Ethernet.

Attenuation: Typically 3. 0 dB/km at 850 nm, slightly lower than OM3 (3. 5 dB/km), providing better signal quality over distance.

Transmission Distances: Supports 10 Gb/s up to 550 m, 40 Gb/s and 100 Gb/s up to 150 m. Backward Compatibility: OM4 is compatible with OM3 systems but offers additional reach and bandwidth margin.

Testing Methods

To confirm that a fiber cable meets OM4 standards, the following tests are commonly performed: Effective Modal Bandwidth (EMB) TestUse a laser source (VCSEL) at 850 nm to measure the EMB. The fiber must meet or exceed 4700 MHz·km to qualify as OM4.

Insertion Loss Test

Measure the optical loss along the fiber using an optical power meter or OTDR (Optical Time-Domain Reflectometer). Ensure the loss is within the limits specified for OM4 to support the intended Ethernet speeds and distances.

Visual Inspection and Core Verification

Confirm the fiber is 50 µm core diameter and laser-optimized. OM4 cables often have an aqua-colored jacket, which helps distinguish them from OM3 (also aqua) and older fibers like OM1/OM2 (orange) or OM5 (lime green),.

Standards Compliance Check

Verify that the cable meets TIA-492AAAD (TIA/EIA standard for OM4) and ISO/IEC 11801 multimode fiber requirements.

Recommended Equipment

Optical Time-

Domain Reflectometer (OTDR): Measures loss, distance, and reflections. Laser Source and Power Meter: For insertion loss and EMB testing. Fiber Identifier or Microscope: To check core size and connector quality.

Summary

To ensure a fiber optic cable is OM4: Confirm it is 50 µm laser-optimized multimode fiber. Test effective modal bandwidth (≥4700 MHz·km at 850 nm). Measure insertion loss to ensure it meets OM4 limits.

Check standards compliance (TIA-492AAAD, ISO/IEC 11801). Optionally, verify jacket color and core diameter for visual confirmation. Following these steps ensures that the fiber cable can reliably support high-speed Ethernet applications and is compliant with OM4 specifications.