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The Growing Significance of Hollow Optical Fiber and its Uses

We live in a fast-paced world where there is the massive influence of technology in nearly every aspect of life. Today, people can communicate faster and do complicated tasks in less time only due to advancements in technology.

The Importance of Fiber Optic

Have you wondered how you can just search for a keyword and get a result within the blink of an eye? Also, you call a number and can instantly hear it ring at the other end.

The fast speed of communication is only possible due to a network of optical fiber cables that submit signals carrying data and information. Since the advent of technology, there have been several means of transmitting data, such as coaxial wire, twisted pair, and fiber optic.

However, when it comes to high-speed signal transmission, nothing can come even close to optical fiber cable. The information or data is transmitted in the form of light pulses. All the easy internet access and connectivity options you get today are because of big fiber optical cables laid under the ground and in the oceans.

The optical fibers are equal to a human hair strand in diameter, but when placed in a cable, they can data faster and over long distances. It is only due to innovation in optical fiber technology that enables the internet in houses, offices, and across a wide range of telecommunication devices.

The principle on which an optical fiber works is ‘total internal reflection’, which says a light needs to pass from denser to rare medium. Also, the angle of incidence needs to be more than the critical angle.

An optical fiber consists of a

  • Core: It is the innermost part of the fiber and denser medium through which light will travel
  • Cladding: It is the outer part of the fiber and rarer medium, and it also supports the core
  • Sheath: It is the outermost part of the optical fiber and prevents any external contaminants

What is the Purpose of Hollow Core Optical Fiber?

The new technology that is a further breakthrough in expanding future communication is ‘Hollow Optical Fiber’. Modern optical fibers usually have a solid glass core, so there is no presence of air.

The standard optical fiber cable passes light through transparent glass cores. However, the signal loss is 0.142 D/km (Decibel per kilometer) meaning that 1% of light is propagated after 100 km. Also, the glass fibers can maintain high speed and power up to a certain limit. Light pulses travel easily within solid glass cores, but half of the intensity is lost after 15 km. After 300 km, the light pulse cannot be even detected, which calls for amplifying the signals at regular intervals.

At the end of the 1990s, there was much research to deliver intense light pulses. Philip St. John Russell from the University of Bath in the UK was first to demonstrate how microstructure optical fibers could pass light through a hollow core.

The presence of ‘Photonic bandgap’ fibers makes it practical to attain low attenuation. One of the research focuses was proving that light travels more than 50% faster in the air than in glass.

Hollow optical fiber works on the principle of passing light through a hollow region with a transmission speed of 660 to 1100 nm (nanometers). These ultra-wide speeds are widely used in quantum networks and industrial laser machining.

How a Hollow Core Optical Fiber Works

A hollow-core optical fiber is a form of fiber optic that passes light through a hollow area. However, when it comes to guiding light through a physical medium, this principle becomes complicated as the refractive index of the fiber core has to be higher than the cladding material. It is quite difficult to obtain a refractive index that is below vacuum or air.

On the contrary, there are other possibilities, such as through a photonic bandgap fiber. Another solution is revolver hollow-core fiber that has silica rings. As the light propagates in thin air, ‘air-guiding fibers’ is another name for ‘hollow-core optical fiber’. But this term is not accurate as it is not the air that transmits light.

The hollow-core optical fibers are filled by air or gas, and air using air means less attenuation, and signals can travel faster over long distances without amplification. But the process is more complicated than it seems. The problem lies in propagating light through a thin substrate such as air. Light pulses tend to travel faster when there is little or no resistance.

The Uses of Hollow Core Optical Fiber

The hollow-core photonic bandgap has many advantages over the traditional solid glass cores. These hollow-core optics can be used in precision sensors and time-frequency measurements. Keeping the light out of glass reduces the distortion of signals and significantly improves the laser beam’s transmission.

Experts came with an idea to add pressure to the air present in the fiber and provide some controlled resistance. The compression of air molecules forms into regular clusters. A resulting sound wave with a high amplitude efficiently diffracts the light from the light source to a weak beam, so light is amplified 100,000 times. This technique makes light a faster medium of transmitting signals.

The hollow core principle can also be used for a different type of light from infrared, ultraviolet apart from laser light. When it comes to the application then compressed gas optical fibers are quite useful in developing accurate thermometers.

The thermometer can effectively measure temperature distribution at any point along with the fiber. For example, if a fire starts in a tall building, the hollow core fiber can determine where the fire began due to an increase in temperature in a particular section of the building.


In recent times, technology has advanced rapidly, and hollow-core fibers are an astounding solution that enables fast data transmission with no or little attenuation. The new technology involves the propagation of light in the air rather than glass. Also, the fibers are resistant to contaminants which makes hollow-core fiber ideal for a tougher environment.

Author Bio:

William Arnold is a professor of physics and also writes for an online magazine. His focus has always been on optical fiber and data communications. He has read several research papers and has also researched hollow fibers on his own.

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