What is hollow optical fiber made of

Hollow optical fibers are made of a central hollow core filled with air or vacuum, surrounded by a structured cladding typically made of high-purity silica, with protective coatings for durability.Core

The central part of a hollow optical fiber is hollow, meaning it contains air, vacuum, or sometimes inert gases depending on the application . Unlike traditional fibers, which guide light through a solid glass core, hollow-core fibers transmit light primarily through the empty space, reducing interaction with glass and minimizing signal loss .

Cladding

Surrounding the hollow core is the cladding, which is usually made of high-purity silica glass arranged in a periodic or structured pattern. This design uses photonic bandgap effects or anti-resonant reflecting mechanisms to confine light within the hollow core . The cladding's structure is critical for guiding light efficiently and maintaining low attenuation.

Protective Layers

Like conventional fibers, hollow-core fibers include protective coatings and buffer layers that shield the delicate internal structure from mechanical stress, environmental damage, and handling . These layers ensure the fiber's longevity and practical usability in telecommunications and other applications.

Summary

In essence, a hollow optical fiber consists of:

• Hollow core: air, vacuum, or inert gas for light propagation
• Structured cladding: high-purity silica glass forming photonic bandgap or anti-resonant structures
• Protective coatings: polymer or other materials to safeguard the fiber This combination allows hollow-core fibers to transmit light at nearly the speed of light in vacuum, reduce nonlinear effects, and achieve lower latency compared to traditional solid-core fibers .