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Guided Wave Optics
Published in Yasuo Kokubun, Lightwave Engineering, 2018
Optical waveguides can be roughly classified by cross-sectional shapes, into cylindrical cross-sectional optical waveguides (primarily used as transmission lines in communications), such as optical fibers and rod lenses, and optical waveguides fabricated on a planar substrate (used in optical integrated circuits and waveguide-type optical devices). There are various cross-sectional structures as shown in Figure 5.1. When classified by material, optical fibers can be a silica optical fiber with silica glass (Si② glass) as the main component and a plastic optical fiber (POF), which makes use of plastics. On the other hand, optical waveguides fabricated on a planar substrate can be formed from thin glass film (silica glass and multicomponent glass) on a silicon substrate or a silica glass substrate using the thin film deposition method and the thick film formation method, or formed by the diffusion of ions in electro-optic crystals (LiNb③ and LiTa③, which are used to use the electro-optical effect and the acousto-optical effect). For those using semiconductors, thin films made of material systems (GaAs/AlGaAs system, GaInAsP/InP system, etc.) that are nearly the same as that in semiconductor lasers are formed on lattice-matched (the crystal lattice constant is equal) substrates by the crystal growth method. On the other hand, a structure where light is confined in the direction parallel to the substrate surface in addition to the normal direction is called the channel waveguide (sometimes called the three-dimensional waveguide). Figure 5.1b through 5.1e corresponds to this category, and to process the core layer into a stripe pattern, photolithographic and etching techniques that are the same as the semiconductor process are used.
Telecommunications
Published in Dave Birtalan, William Nunley, Optoelectronics, 2018
Plastic optical fiber (POF) is made with a core (low loss area) and jacket (protective covering), and is designed to have the lowest attenuation (optical loss) at 650 nm wavelength. It is typically used in controlled environments with relative short distances (100 m or less) and data rates no higher than 100 Mbps.
Numerical solution of coupled radiative and conductive heat transfer’s equations in PolyMethylMethAcrylate by the finite difference method
Published in Radiation Effects and Defects in Solids, 2021
Seyed Milad Mousavi, Cyrus Aghanajafi
In recent decades, communication between humans has increased. Because of high growth rate, this issue needs improvement in the field of communicating systems and data transfer. The most suitable material for these applications, the optical fiber, was found, so the researchers have studied different types of composite optical fibers, especially the plastic optical fiber (POF) (1,2). Beyond these activities, this transmission medium was stopped for a few years because of the lack of support in commercial fields. Composite fiber has various applications, such as light transmission sensing, data transmissions for optical signals, and deformation detection, which is used in solid mechanical experimental research studies and in chemical sensing (3–5). Its applications are really important because this improves the reliability of electrical machines, ICs, and microelectronics. But this research focused on the usage of the poly methyl meth acrylate- plastic optical fiber (PMMA-POF) for data transfer.
Mini review: Recent advances in long period fiber grating biological and chemical sensors
Published in Instrumentation Science & Technology, 2019
A simulated dispersion curve is shown in Figure 5, where the red point is the turning point of dispersion. When the dispersion turning point of a certain order mode is lower than the period of grating and the ambient refractive index becomes larger, the resonant dip coupling deepens as the dispersion curve moves up, which is reflected as intensity modulation. As the ambient refractive index continues to increase and the dispersion turning point is higher than the period, two resonant wavelengths satisfying the phase matching condition appear in a certain order, which is called dual-peak resonance. The reduction of the diameter of the cladding has also shown to be an effective way to improve sensitivity. Furthermore, LPFGs based on a single mode, on a photonic crystal fiber, and based on plastic optical fiber have been shown to possess the advantages of the fiber and the LPFG.
Simultaneous measurement of humidity and temperature using a polyvinyl alcohol tapered fiber bragg grating
Published in Instrumentation Science & Technology, 2018
Sheng-xi Jiao, Yong Zhao, Jiang-jin Gu
In recent years, various humidity sensors based on optical fiber structures have been proposed, such as tapered fiber,[234] plastic optical fiber,[3] fiber Bragg grating,[56789] long-period fiber grating,[10111213] and Fabry–Perot interferometers.[14151617] However, conventional optical fiber is insensitive to humidity because the light is strictly bound in fiber core. Tapered fiber is efficient to reduce cladding region and leak out the light of core mode into the fiber cladding, and the humidity sensing can be achieved easily by coating humidity sensitive materials on the optical fiber sensing structures. The refractive index or thickness of hygroscopic materials changes with varied environmental humidity due to the swelling and deswelling effects.