NLS-Glossary

is the central region of an optical fiber that has a higher refractive index than the outer region. Most of the light propagates through the core region of a fiber.                                  

Characters Per Inch. A common measurement for bar code density.                                                                                                                                                                               

is the angle of incidence that results in a refracted wave at 90° when the incident wave is traveling in a medium of lower refractive index and is incident at a boundary with a material with a higher refractive index.

is a three-dimensional periodic arrangement of atoms or molecules or ions. 

A characteristic property of the crystal structure is its periodicity and a degree of symmetry. For each atom the number of neighbors and their exact orientations are well defined, otherwise the periodicity will be lost. There is therefore a long range order resulting from strict adherence to a well defined bond length and relative bond angle (or exact orientation of neighbors).

is a process by which crystals of a substance are formed from another phase of that substance, for example, from the melt by solidification just below the fusion temperature or by condensation of the molecules from the vapor phase onto a substrate. The crystallization process initially requires the formation of small nuclei of the crystal phase which contain a limited number (perhaps ${10}^3-{10}^4$ ) of atoms or molecules of the substance. Following nucleation, the nuclei grow by atomic diffusion from the melt to the nuclei.

are generally made by an end-pumped simple Bragg grating based cavity with some amplifying stages when there are specific requirements constraining the  optical output characteristics i.e. wavelength.