What is a Hollow Optical Fiber? How is it Different from Traditional Solid Optical Fibers?
Time:2025-09-15
Views:12
1. What is a Hollow-Core Fiber?
A hollow-core fiber (HCF), as the name suggests, is an optical fiber structure with a hollow central section.
The central part of a hollow-core fiber is air, surrounded by cladding material, and light can transmit in specific regions between the cladding and the central hollow section. This design allows optical signals to transmit through the central hollow cavity of the fiber, rather than passing through a glass medium (the core of traditional solid-core fibers is made of glass).
From the perspective of manufacturing processes, the production of hollow-core fibers requires precise control over parameters such as the refractive index distribution of the material and the size of the hollow section. They are usually made of special glass or polymer materials, and during the manufacturing process, indicators like the fiber’s concentricity and surface smoothness must be ensured to meet the requirements of optical transmission.
2. How Does It Differ from Traditional Solid-Core Fibers?
1) Structural Differences
Solid-core fibers: Their structure is relatively simple, mainly consisting of a core, cladding, and coating. The core serves as the main channel for optical transmission, mostly made of high-purity silica glass with a relatively high refractive index. The cladding has a slightly lower refractive index, enabling total internal reflection of light at its interface with the core. The coating wraps around the cladding, functioning to protect the fiber from damage caused by the external environment.
Hollow-core fibers: Their central part is hollow, without the solid core medium of traditional fibers. The surrounding material forms the cladding, and light transmits in specific regions between the cladding and the central hollow section. The cladding material of hollow-core fibers also needs to have an appropriate refractive index to ensure that light undergoes total internal reflection in this special region and transmits forward.
2) Comparison of Light-Guiding Principles
Solid-core fibers: Based on the principle of total internal reflection. When light travels from the optically denser core to the optically rarer cladding at an angle greater than the critical angle, total internal reflection occurs at the interface. Light transmission relies on the refractive index difference between the core and the cladding.
Hollow-core fibers: Expand on the principle of total internal reflection—light undergoes total internal reflection at the interface between the cladding and the hollow section. Unlike solid-core fibers, light transmission in hollow-core fibers does not depend on total internal reflection in the solid core medium; instead, it utilizes the refractive index difference between air (in the hollow section) and the cladding material.
3) Differences in Performance Characteristics
(1) Loss Characteristics
Solid-core fibers: During long-distance transmission, solid-core fibers exhibit certain losses, mainly including Rayleigh scattering loss, absorption loss, and nonlinear loss.
Hollow-core fibers: The loss of hollow-core fibers is usually lower than that of traditional solid-core fibers. Due to the hollow center, the number of scattering centers is reduced, significantly lowering the loss caused by Rayleigh scattering. Meanwhile, at certain wavelengths, the absorption loss of hollow-core fibers is also extremely low, as there is no solid material component that absorbs light. Additionally, the interaction between light and the material in hollow-core fibers is weak, so nonlinear effects are significantly reduced—this gives them better performance in high-power optical transmission.
(2) Bandwidth Characteristics
Solid-core fibers: The bandwidth of solid-core fibers is mainly affected by dispersion. However, solid-core fibers have relatively high modal dispersion and material dispersion. Especially in high-speed, long-distance optical communication systems, measures such as dispersion compensation need to be adopted to reduce the impact of dispersion.
Hollow-core fibers: In comparison, hollow-core fibers have better bandwidth performance. Due to the presence of the hollow section, both modal dispersion and material dispersion during light transmission are relatively small, enabling them to support higher data transmission rates.
(3) Heat Dissipation Performance
Solid-core fibers: The heat generated by light is mainly concentrated in the core. However, the thermal conductivity of the core material is limited, making it difficult for heat to dissipate. During high-power optical transmission, the increase in core temperature may lead to degradation of fiber performance, or even damage to the fiber.
Hollow-core fibers: In contrast, hollow-core fibers have better heat dissipation performance. The central hollow section provides a channel for air, allowing heat to dissipate more effectively through this hollow part. This excellent heat dissipation performance enables hollow-core fibers to meet the requirements of high-power optical transmission and ensure the stability and reliability of optical transmission.
(4) Anti-Interference Capability
Solid-core fibers: There is a certain interaction between light and the core material, which in some cases makes the fiber vulnerable to external electromagnetic interference. Furthermore, impurities and defects in the fiber may cause scattering and absorption of optical signals, affecting signal quality.
Hollow-core fibers: Since the center of hollow-core fibers is hollow, the interaction between light and solid materials is reduced, giving them strong resistance to electromagnetic interference. At the same time, the hollow structure also reduces the impact of impurities and defects on optical signals, allowing for better preservation of signal integrity.
3. Applications of Hollow-Core Fibers?
Hollow-core fibers possess unique advantages, making them suitable for specific application scenarios, such as:
1) High-Power Laser Transmission
Owing to their low loss, low nonlinear effects, and excellent heat dissipation performance, hollow-core fibers have distinct advantages in the field of high-power laser transmission. For instance, in areas like laser processing and laser medicine, hollow-core fibers can transmit high-power laser beams safely and efficiently.
2) High-Speed Optical Communication
With the continuous growth of data traffic, higher requirements have been put forward for the bandwidth and transmission rate of optical communication systems. The high-bandwidth characteristic of hollow-core fibers makes them an ideal choice for future high-speed optical communication, and they are expected to be widely used in fields such as data centers and backbone networks.
3) Applications in Special Environments
Hollow-core fibers exhibit properties like high-temperature resistance and radiation resistance, enabling them to function in certain special environments. For example, in optical communication near industrial high-temperature furnaces and in space exploration, hollow-core fibers can transmit optical signals stably.
Sales Team
Sales Team