The Secret of Fiber Excess Length

The Secret of Fiber Excess Length

When you are watching videos or playing games, the Internet speed suddenly slows down? In addition to complaining to the operator, a "spring" hidden in the optical cable may be the key! This "spring" is the excess length of the optical fiber - it balances stretching, squeezing and temperature changes through exquisite engineering technology, silently protecting your smooth network. Let's take 3 minutes to reveal its secret.

Excess length: "Invisible spring" in the optical cable
If the optical fiber is compared to a glass fiber, the excess length is the slack it reserves in the plastic casing (as shown below). This design can be called the "black technology" in the communication industry:

1. Tension knob: pay-off tension control
Too tight (>1N): The spring is straightened and loses its buffering ability (such as a bicycle seat that is adjusted too high and is prone to breakage)
Too loose (<0.5N): The spring shakes randomly, causing signal reflection (such as a guitar string that is too loose and out of tune)
Accurate value: 0.6~0.8N (equivalent to the strength of lightly supporting a strand of hair with your fingers)

2. Temperature scale: Compensation for thermal expansion and contraction of materials
High temperature trap: The casing expands when heated → contracts after cooling, just like steamed buns shrink after steaming, and 10% more "dough" must be reserved in advance
Low temperature crisis: Material shrinkage difference at -40℃ = distance error from Beijing to Tianjin! It needs to be resolved through step cooling process (first air cooling to fix the shape, then water cooling to reinforce)

3. Lubrication code: The magical effect of ointment
This translucent gel is not only a filler, but also a "spring maintenance agent":
Physical lubrication: Reduce fiber friction (analogous to butter applied on door shafts)
Chemical protection: Isolate water and oxygen corrosion (like mobile phone waterproof coating)
Intelligent buffering: High temperature becomes thinner to absorb vibration, low temperature becomes thicker to fix the position (similar to non-Newtonian fluid)

Your Internet speed has been saved like this
Real case: Due to improper ointment formulation, a submarine optical cable has abnormal excess length under the change of water temperature in the Pacific Ocean, resulting in a 30% drop in Internet speed in a certain area. Engineers:

• Adjusted the tension control system (error reduced from ±0.1N to ±0.03N)
• Used temperature adaptive grease (viscosity change rate reduced from 20% to 5%)
• Increased laser online monitoring (detection of excess length per meter)

Finally, the transmission stability of the optical cable was improved by 40%, which is equivalent to the experience leap from 3G to 4G! Next time when WiFi freezes, don’t forget - in places you can’t see, thousands of "springs" are protecting the data torrent with micron-level accuracy. This is exactly: Although the excess length is small, it hides the mystery, the tension temperature grease system.The optical fiber is protected to transmit thousands of miles, and there is zero delay at the ends of the earth.