Date Published: October 26, 2025
Author: Nebojsa Kostic
Light as Information: Everything You Need to Know About Optical Cables
When you stream a movie in high resolution, join a video conference without delay, or download gigabytes of data in seconds, you probably don’t think about what’s hidden behind your wall or beneath the street. In an increasing number of cases, the answer is a thin strand of glass that transmits information at the speed of light. This is the optical cable — a silent revolution that has become the backbone of the modern digital world.
But what exactly is fiber optics, how does it work, and is our future truly “optical”? Here’s a clear, all-in-one explanation — optical networking, demystified for everyone.
A Brief History: From Water Fountains to the Global Network
Optical fiber is a thread of glass (or sometimes plastic) through which light pulses carry data instead of electricity. The concept of bending and guiding light through a medium dates back to the 19th century, when scientists demonstrated total internal reflection by transmitting light through a jet of water.
The true revolution began in the 1960s. Dr. Charles Kuen Kao — awarded the 2009 Nobel Prize in Physics — discovered that ordinary glass caused too much signal loss. He theorized that by using ultra-pure glass, attenuation could be reduced enough to make long-distance data transmission possible. In 1970, Corning Glass Works (now Corning Inc.) produced the first low-loss fiber, paving the way for commercial deployment.
Today, optical fiber is the primary transmission medium for internet backbones, metropolitan networks, and increasingly — the “last 100 meters” to your home (FTTH – Fiber to the Home).
Optics vs. Copper: Why Light Outpaced Electricity
For decades, copper cables such as coaxial and twisted pair lines were the global standard. Fiber optics surpassed them in almost every category:
- Massive capacity and range: Optical fibers can carry terabits per second across tens or even hundreds of kilometers without regeneration.
- Immunity to interference: Because the signal is light, it’s unaffected by electromagnetic or radio frequency noise.
- Security and weight: Optical data can’t be tapped without physically cutting the fiber, and cables are lighter and thinner.
- Lower latency: Photons travel through glass at roughly 200,000 km/s, minimizing delay compared to electrons in copper.
Quick Comparison: Fiber vs. Copper
| Characteristic | Optical Cable (Light) | Copper Cable (Electricity) |
|---|---|---|
| Speed & Capacity | Extremely high (Tbps) | Limited (Mbps–Gbps) |
| Reach (without amplification) | Tens to hundreds of km | ~100 m typical for Ethernet |
| Interference | Immune | Susceptible to EMI/RFI |
| Weight & Size | Thin and lightweight | Heavy and bulky |
| Data Security | Difficult to tap | Can be intercepted |
| Grounding | Not required | Mandatory between buildings |
Who Makes Optical Cables?
The market for ultra-pure glass fibers is dominated by global manufacturers, including:
- Corning (USA)
- Prysmian Group (Italy)
- Sumitomo Electric (Japan)
- Fujikura / OFS (Japan / USA)
How Far Can Optical Links Go?
1. Without Amplifiers (Standard Modules)
Direct links between devices — such as network switches — use optical transceivers:
- Multi-mode (OM3/OM4): Short-range use in buildings or data centers (up to 300–500 m).
- Single-mode (OS2 / ITU-T G.652): Long-distance use. Common 10G modules include:
LR (Long Range) – up to ~10 km
ER (Extended Range) – up to ~40 km
ZR (Zero Dispersion) – up to ~80 km
2. With Amplifiers (Long-Haul Networks)
On metropolitan, intercity, or submarine routes, optical signals are boosted using EDFA (Erbium-Doped Fiber Amplifiers). These devices amplify light directly without converting it to electricity. Repeaters are typically spaced 60–100 km apart, enabling spans of hundreds or even thousands of kilometers.
Can Electricity Flow Through Optical Cables?
No — pure glass is a dielectric and does not conduct electricity. That’s actually an advantage, providing immunity to lightning and electromagnetic surges.
There are two notable exceptions:
- Power-over-Fiber (PoF): A specialized method where a high-power laser sends energy along a fiber, converted back to small amounts of electricity by a photodiode. Used in environments where electrical isolation is critical.
- Hybrid Cables: A common solution that combines optical fibers (for data) and copper wires (for power) within the same jacket — ideal for remote cameras, Wi-Fi access points, or 5G antennas.
Standards, Connectors and Tools
Fiber Types
- Single-mode: Standard OS2 (G.652) for long-distance links; G.657 is a bend-insensitive version used for FTTH installations.
- Multi-mode: Standards OM3, OM4, OM5 serve short-range, high-speed connections in data centers.
Connectors
- LC (Lucent Connector): Compact and widely used in active network equipment.
- SC (Subscriber Connector): Larger push-pull type, common in wall outlets.
- MPO/MTP: Multi-fiber connectors (12, 24 fibers) for 40G–400G high-density links.
Essential Tools for Working with Fiber
- Fiber stripper: Removes protective coating from 125 µm glass fibers.
- Precision cleaver: Cuts fibers at perfect 90° angles for splicing.
- Fusion splicer: Aligns and welds two fibers using electric arcs.
- VFL (Visual Fault Locator): Red laser tool to identify breaks or bends.
- OTDR (Optical Time-Domain Reflectometer): Measures distance, losses, and reflections along the fiber.
- Cleaning materials: Alcohol and lint-free wipes are essential.
Can You Install Fiber at Home?
Yes, but carefully. You can safely use a pre-terminated patch cable (for example LC-LC) to extend your provider’s optical outlet to another room. Always respect the minimum bend radius and protect the connectors during installation.
No, not for raw fiber work. Splicing or attaching connectors to bare fiber requires expensive precision tools and training. FTTH providers typically handle installation up to the optical wall outlet.
Global Trends and Coverage
Europe and much of the world are moving rapidly toward full-fiber infrastructure. According to the FTTH Council Europe 2024 report, household fiber coverage across 39 European countries averaged 74.6 %. Fiber penetration continues to rise globally thanks to broadband demand, cloud computing, and 5G backhaul expansion.
Recycling and Cable Theft
Recycling: Optical cables can technically be recycled, but the process is complex. Fibers are protected by multiple plastic layers, gels, and Kevlar reinforcements — making separation difficult and rarely economical.
Theft: Unlike copper, optical cables have no scrap value. They consist mostly of glass and plastic, so fiber theft is virtually non-existent. The main risks are accidental cuts during construction or deliberate vandalism, not material resale.
Frequently Asked Questions (FAQ)
Q: Is there “electricity through fiber”?
A: No. Optical fibers transmit light, not electricity. Exceptions include Power-over-Fiber systems and hybrid cables that combine data and power lines.
Q: What is the maximum distance without amplification?
A: Standard 10 G modules reach up to 10 km (LR), 40 km (ER), or 80 km (ZR). Long-haul systems use EDFA repeaters every 60–100 km for intercity or submarine links.
Q: Is the future really optical?
A: Absolutely. With growing bandwidth demands from cloud, AI, and 5G, optical infrastructure is the only medium capable of sustaining global data growth.
Q: Which standard should I look for in home fiber (FTTH)?
A: Use single-mode G.657.A2 fiber with SC/APC (green) connectors at the wall and LC on your router or ONT.
Q: Is fiber more expensive than copper?
A: For short, low-speed links, copper is cheaper. But at higher speeds and distances, fiber offers lower cost per Gbps and superior performance overall.
This article provides an educational overview of optical fiber technology, its history, standards, and global impact on modern communications.