What is a Hollow Core Fiber Cable?
A hollow core fiber cable is an optical fiber that leads light essentially inside a hollow region, with only a small area of the optical power propagating in the solid fiber material. This should not be possible, as per the standard physical method for guiding light in fiber; the refractive index of fiber core must generally be higher than that of the surrounding coating material. There is no way to get a refractive index of glass lower than that of vacuum or air, at least in the optical spectral range.
When compared to conventional fiber with a solid silica core, light travels about 50% faster in a hollow-core fiber cable. In comparison to traditional optical fiber, light transferred in a hollow-core fiber arrives 1.54 microseconds more quickly for each kilometer traveled.
Properties of Hollow Core Fiber Cables
- Range of Wavelengths with Guidance
In most cases, the wavelength ranges in which the photonic bandgap guiding mechanism operates are quite restricted. People usually consider it as a drawback in some applications, but it can also benefit others, such as attempting to suppress the propagation of undesirable light.
The wavelength range with light guidance can be significantly expanded by using a hollow-core fiber with a so-called Kagomé lattice design. For example, a vast spectral generation could benefit from this. The Kagome fiber design is fundamentally different from a photonic bandgap fiber in that it does not depend on a photonic bandgap.
Some optical properties of photonic bandgap fibers differ significantly from those of photonic bandgap fibers. The gradient of the chromatic dispersion, for example, is relatively low, which is advantageous for pulse compression. Some designs have minimal light overlap with the silica structures (on the order of 0.01 percent), allowing the guidance of beams with high optical peak powers.
- Loss of Propagation
Hollow-core fibers had much higher propagation losses than solid-core fibers at first, especially when single-mode guidance was required. There are, however, some very effective methods for addressing this issue. Recently, some hollow-core fibers with significantly lower losses are roughly comparable to state-of-the-art silica fibers at an optimum wavelength of around 1.5 m.
Similar low losses appear to be possible on a broader wavelength range, where silica absorption or scattering is significantly higher. It may even be possible to construct telecom fibers with losses lower than the upper bound of solid-core silica fibers. The low-intensity profile with the glass allows light to be guided even at wavelengths where the glass material’s transparency is weak.
- Nonlinearities are Weak
Because light is primarily guided in air, with only a weak spatial overlap with the glass structure, nonlinear effects are minimized (especially for ultrashort pulses with high peak power), and a high damage threshold is possible. Because of the low density, the Kerr effect in the air is about three orders of magnitude poorer than in glass.
- Dispersion of Colors
The fiber design can control the chromatic dispersion, which is especially useful for photonic bandgap strands with small mode areas. This is also useful for guiding ultrashort pulses. In ultrashort pulses, large amounts of chromatic dispersion and nonlinearity can cause significant pulse distortions.
The chromatic dispersion of fibers with a large hollow core is typically weak, with little reliance on design details. This could be useful for supplying ultra-short pulses, for instance.
- Lower Latency
Guided light has a group velocity that is closely similar to that of vacuum light. This means that signal transmission through hollow-core fibers will have much lower latency.
- Decreased Coupling
In some cases, having a low optical field overlap with the laser-active dopant in a rare-earth-doped fiber is advantageous. For example, this could make it easier to realize a 978-nm doped fiber laser or fiber amplifier, where suppressing unwanted emission at longer wavelengths is more challenging.
Applications of Hollow Core Fiber Cables
The following are the main areas where hollow-core fibers are expected to be used:
- You can use this hollow-core fiber cable to supply laser radiation in the form of ultrashort pulses with high peak power. For example, with high average power in a wide range of wavelengths from ultraviolet to mid-infrared.
- They could be helpful for data transmission, especially if a low latency (time delay) is required. Also, low-loss data transmission can be used in the spectral range where solid-core silica fibers’ absorption losses are too high. Higher data rate transmission capacities can be achieved by passing light with a significantly larger overall optical bandwidth.
- Because the interaction of a light beam influenced by a hollow fiber is far more intense than a free-space beam in a multiple gas cell. Moreover, you can easily gather the Raman lasers containing gases. Similarly, you can also use the gas-filled hollow fibers to discover a variety of other nonlinear functions.
Advantages of Hollow Core Fiber Cables
Because hollow-core fiber cables (indoor/outdoor fiber optic cable) can travel through the air rather than light. Furthermore, it has many advantages over traditional optical fiber. It will soon replace it in many applications.
The advantage of hollow optic fiber cable is that it does not limit the performance of the optical fiber. The silicon materials and other associated components affect the traditional visual damage level, absorption and group velocity dispersion parameters, and nonlinear effects.
Hollow fibers can achieve almost 99 percent of light in the air instead of in the glass through careful design. Moreover, it can significantly reduce the material properties of optical fibers. As a result, hollow fiber optic cable transceivers continue to outperform optical fiber in several key areas. These hollow core fibers are highly useful in UV and MIR.
The fiber optic cable has no fiber core, which reduces loss, increases communication distance, and prevents dispersion caused by interference phenomena. It also supports more wavelengths and allows for more robust light power injection. Its communications capacity is approximately 1000 times the cable currently in use.