Table of Contents
Photonic Crystal Fibers: Structure, Principles, and Applications
Fundamental Properties and Light Guidance Mechanisms
Photonic crystal fibers and fiber lasers are two of the most rapidly developing spheres of optics and photonics over recent years. Photonic crystal fibers are a new class of optical fibers. They have a unique artificial-like crystal microstructure. They can guide light not only through a common total internal reflection mechanism but also with the use of the photonic bandgap effect.
Design Flexibility and Dispersion Engineering
The construction of PCFs is flexible. There are several parameters to manipulate: the period of the grating, the air hole shape, the refractive index of the glass, and the type of grating. Freedom of design permits one to obtain single-mode fibers, which are single-mode in all optical range, and a cut-off wavelength does not exist. By manipulating the structure, it is possible to design the required dispersion properties of the fiber. PCFs can be fabricated having zero, low, or anomalous dispersion at visible wavelengths. The dispersion can also be depressed over a large range. Regardless of the type of glass and structure, the usual method of photonic crystal fiber fabrication is multi-rate thinning.
Materials and Waveguiding Advantages
In a photonic crystal fiber, light is absorbed in the core, providing a better waveguide to photons than standard optical fiber. The polymers used instead of glass in PCF provide the advantage of a more flexible fiber, which provides easier and less expensive installation. Different photonic crystals according to various photonic gratings are produced, depending on the required properties of the propagated light.
Current Applications of Photonic Crystal Fibers
PCF is finding applications in fiber-optic communications, fiber lasers, nonlinear devices, high-power transmission, highly sensitive sensors, and other areas.
Significant features also make photonic crystal fibers very attractive for several specific areas in case as telecom components, quantum optics, the guidance of cold atoms, and Bragg fiber.
Photonic crystal fibers mix characteristics of photonic crystals and classical fibers. Research on photonic crystal fibers is still unexplored. Apart from already developed applications as fiber dispersion compensation, supercontinuum generation, and particle guidance is expected a series of new applications in telecommunication, sensing, beam delivery, surgery, spectroscopy, and fiber lasers is expected in the next few years.