NLS-Glossary

are prisms made from birefringent crystals for producing a highly polarized light wave or polarization splitting of light. The Wollaston prism is a polarization splitter in which the split beam has orthogonal polarizations. Two calcite (or quartz) right angle prisms A and B are placed with their diagonal faces touching to form a rectangular block. Various Wollaston prisms with typical beam splitting angles of 15 - 45° are commercially available. The Wollaston prism is a beampolarization splitter. E1 is orthogonal to the plane of the paper and also to the optic axis of the first prism. E2 is in the plane of the paper and orthogonal to E1. e-ray is the extraordinary wave and o-ray is the ordinary wave.

Binary Synchronous Communication. Protocol supported by the AS/400 for communicating with other AS/400, IBM mainframe, System/36, and System/38 systems.                

is the basic unit of information in digital communication systems and corresponds to the presence or absence of pulses.                                                                                               

is the fraction of all bits that are wrong (corrupted) within a long series of bits of information received over a long period of time. Stated differently, it is the ratio of errors to the total number of bits transmitted during a long digital transmission period. The lower the BER. the better is the transmission system.

is the rate at which bits are transmitted in a digital communications system. Maximum rate at which the digital data can be transmitted along the fiber is the bit rate capacity,B (bits per second), and is directly related to the dispersion characteristics of the fiber.

is the product of the bit rate capacity and fiber length and is a measure of the information carrying capacity of a fiber. Generally, the dispersion or time spread of an optical pulse increases with distance and the bit rate capacity consequently decreases with distance. In multimode fibers, B decreases approximately linearly with L so that BL is nearly constant and fiber characteristic. Strictly, however, BL is not constant (especially for single mode fibers) and one should compare BL products of fibers of comparable length. See bandwidth.