The Essence of 6G Network Latency Challenges: Why Fiber Materials Have Become a Critical Bottleneck?
Physical Law Constraints
The speed of light signals in fiber optics is approximately 200,000 km/s, but 6G requires end-to-end latency ≤ 0.1 ms, equivalent to a signal transmission distance of only 20 km. This means:
Traditional "distance-for-time" strategies are ineffective; signal loss must be compressed at the material level.
The attenuation coefficient of each kilometer of fiber needs to decrease from 0.2 dB/km in the 5G era to below 0.15 dB/km, reducing optical power loss by 25% per kilometer.
Amplification Crisis of Nonlinear Effects
When the optical power density is too high, nonlinear effects such as the Kerr effect and stimulated Raman scattering (SRS) can cause signal distortion. High-frequency transmissions in 6G (such as terahertz waves) exacerbate this issue, forcing materials and processes to achieve three major breakthroughs:
Purity Control: Metal impurities (Fe, Cu) in quartz glass must be below 1 ppb (one part per billion).
Structural Innovation: Transition from solid-core fibers to hollow-core fibers (Hollow-Core Fiber) to reduce interactions between light and materials.
Coating Technology: Develop low-modulus coatings to suppress micro-bend losses that interfere with high-frequency signals.
Material and Process Innovations for Ultra-Low Loss Fibers
1.Quartz Purification: Quantum Leap from "Industrial Grade" to "Electronic Grade"
VAD (Vapor Axial Deposition) Process Upgrade: Traditional deposition rates are about 5 g/min, while new high-speed VAD increases this to 15 g/min. Plasma-assisted chemical vapor deposition (PA-CVD) reduces hydroxyl (OH⁻) content to below 0.1 ppm, lowering attenuation in the 1383 nm band by 40%.
Material Revolution: Using ultra-high-purity silicon tetrachloride (SiCl₄) with metal impurity detection precision of 0.01 ppt (one part per trillion). This increases costs from 15% to 35% but achieves an ultimate performance of 0.12 dB/km attenuation.
2. Hollow-Core Fibers: Disrupting Physical Laws with "Vacuum Light Speed Channels"
Photonic Crystal Structure Design: Periodic air hole arrangements form photonic bandgaps, allowing light waves to travel through the air core. The theoretical attenuation can be as low as 0.001 dB/km. In 2025, NKT Photonics' experimental line achieved 0.3 dB/km, approaching the 6G commercial threshold.
Pressure Resistance Breakthrough: Using carbon nanotube-reinforced polymer cladding, the side pressure resistance of hollow-core fibers increased from 50 N/cm to 200 N/cm, meeting underground pipeline deployment requirements.
3. Coating Materials: From "Passive Protection" to "Active Tuning"
Thermo-Optic Effect Compensation Coating: Develop UV-cured resins doped with erbium nanoparticles. Their refractive index changes opposite to that of the fiber, reducing thermal mode noise by 70% in environments from -40°C to 85°C.
Self-Healing Coatings: Introduce microencapsulated siloxanes that release repair agents when micro-cracks appear on the fiber surface, reducing annual field deployment loss rate from 0.02 dB/km to 0.005 dB/km.
Global Leader Technology Route Comparison
Breaking the Cost and Scaling Challenges
ROI Calculation for Equipment Upgrades
For a production line with an annual output of 1 million core kilometers of fiber:
Key Conclusion: The investment payback period for traditional process upgrades is about 2.3 years, while advanced technologies require government subsidies or strategic customer prepayments.
In the 6G era, fiber optics are no longer passive physical media but intelligent network nerves with self-sensing and self-optimization capabilities. Material and process innovations not only focus on minor improvements in attenuation coefficients but will also reshape the global optical communication industry's power landscape. As Chinese enterprises approach Corning in ultra-pure quartz, and hollow-core fibers move from laboratories to the Pacific Ocean floor, this silent material revolution is writing a new chapter in human connectivity.
