Performance parameters of ordinary optical cables in computer rooms

Ordinary optical cables in computer rooms are designed for low-loss, high-bandwidth data transmission, with strict requirements for bending, fire safety, and mechanical durability.

Transmission Performance

Optical cables in computer rooms typically use multimode fibers (OM1, OM2, OM3, OM4) or single-mode fibers (OS1/OS2), supporting high-speed data over short to medium distances . Key transmission parameters include:

• Attenuation: Single-mode fibers (ITU-T G.652) have low loss, typically ≤0.4 dB/km at 1310 nm and 1550 nm wavelengths . Multimode fibers have higher attenuation due to modal dispersion, limiting bandwidth-distance product (e.g., OM4 ~4700 MHz·km), .
• Bandwidth: Multimode fibers are rated by modal bandwidth, affecting maximum data rates over given distances. Single-mode fibers support longer distances with minimal dispersion .
• Bending Loss: Microbends and macrobends can scatter light, increasing signal loss. Standard practice is to maintain a minimum bend radius of 10 times the cable diameter; bend-insensitive fibers (ITU-T G.657.B3) tolerate tighter bends with minimal loss .

Mechanical and Environmental Characteristics

Cables must withstand installation and operational stresses:

• Tensile Strength: Cables are designed to resist pulling forces during installation .
• Crush and Impact Resistance: Indoor cables are tested for mechanical pressure and accidental impacts .
• Temperature Range: Designed to operate within typical indoor temperature variations without performance degradation .
• Fire Safety: Jackets are made from PVC or LSZH (Low Smoke Zero Halogen) materials to prevent flame propagation and reduce toxic smoke in case of fire .

Construction and Installation Considerations

• Jacket and Sheathing: Protect fibers from mechanical damage and environmental factors. LSZH is preferred in computer rooms for safety .
• Strength Members: Aramid yarn or fiberglass rods provide tensile support without stressing the fiber .
• Connector Types: Common connectors include LC, SC, and ST, chosen for compatibility with patch panels and transceivers .
• Identification: Cables are color-coded and labeled for easy management and maintenance .

Factors Affecting Performance

• Material Impurities: Hydroxyl ions (OH⁻) in the glass core can absorb light, especially at 1380 nm, increasing attenuation .
• Connector and Splice Quality: Misalignment or contamination can cause significant signal loss; proper cleaning and inspection are essential .
• Installation Practices: Avoiding tight bends, excessive pulling, and crushing ensures long-term performance . In summary, ordinary optical cables in computer rooms are optimized for high-speed, low-loss data transmission with strict adherence to mechanical, environmental, and fire safety standards, ensuring reliable network performance in indoor environments .