Hydrogen compounds are only required to contain carbon. However, most of them also contain hydrogen, and because it is the carbon-hydrogen bond which gives this class of compounds most of its particular chemical characteristics, carbon-hydrogen bonds are required in some definitions of the word "organic" in chemistry. Millions of hydrocarbons are known, and they are usually formed by complicated synthetic pathways that seldom involve elementary hydrogen. Compounds of hydrogen are often called hydrides, a term that is used fairly loosely. The term "hydride" suggests that the H atom has acquired a negative or anionic character, denoted H, and is used when
Hydrogen darkening loss budget being exceeded. To prevent this, coatings such as carbon are applied to the fiber, and hydrogen capturing gels are used to buffer the fiber, and other proprietary techniques may be used to prevent hydrogen atoms from reaching the glass fiber via the cable sheath. Hydrogen darkening Hydrogen darkening is a physical degradation of the optical properties of glass. Free hydrogen atoms are able to bind to the SiO silica glass compound forming hydroxyl (OH)—a chemical compound that interferes with the passage of light through the glass. The problem is particularly relevant to fiber optic cables—particularly in oil and