From Coaxial to Fiber

Coaxial cable, invented in 1880 and patented by Oliver Heaviside, became the backbone of cable television networks throughout the latter half of the 20th century. The basic architecture is elegantly simple yet highly effective for its purpose.

The genius of coaxial cable lies in its electromagnetic shielding. The outer conductor acts as both a return path and an electromagnetic shield, protecting the inner conductor from external interference. This design allows coaxial cables to carry high-frequency signals over longer distances than twisted-pair wiring could manage.

This architecture proved remarkably successful. By the early 2000s, HFC networks were delivering broadband speeds that embarrassed incumbent telephone companies still relying on DSL over copper telephone lines. The key innovation was pushing fiber deeper into the network, reducing the distance that signals traveled over lossy coaxial cable.

The physics behind fiber optics relies on total internal reflection. The core has a slightly higher refractive index than the cladding (1.47 vs 1.46), causing light to reflect at the boundary rather than escape. This allows light signals to travel vast distances with minimal loss—modern single-mode fibers achieve attenuation as low as 0.15 dB/km at 1550nm wavelength.

Finland has emerged as a European leader in fiber optic deployment. As of September 2024, Finland's fiber-optic broadband network reaches nearly 2 million homes—68% of Finnish households. This represents a 7 percentage-point increase over a single year, demonstrating aggressive expansion.

The economics are compelling. Comcast reported that upgrading to DOCSIS 4.0 costs under $200 per passing—a fraction of fiber deployment costs. This cost advantage is why cable operators aren't rushing to abandon their HFC networks.

Recent breakthroughs have been dramatic. In 2020, researchers at the University of Southampton published results showing hollow-core fibers with attenuation lower than solid-core fibers at multiple wavelengths—0.28 dB/km in the C and L telecommunication bands.

The quest for a cable "more durable and faster" than fiber at lower cost faces insurmountable physics. Speed is bounded by the speed of light in the medium—fiber already approaches this limit. Durability favors copper, but at severe bandwidth sacrifice. Cost favors leveraging existing infrastructure, which means HFC/DOCSIS for much of the world.

Perhaps the real innovation isn't finding a single technology to replace fiber, but rather building intelligent hybrid networks that dynamically select the optimal technology for each segment.