The material and coating of a beam splitter significantly impact the degree of attenuation. For example, in quantum information the beam splitter plays essential roles in teleportation, bell measure-ments, entanglement and in fundamental studies of the photon. Shortpass splitters are characterized by a "cutoff" wavelength below which light is transmitted (and above which light is reflected), while longpass splitters are characterized by a "cut-on" wavelength above which light is transmitted. Understanding how beam splitters affect signal attenuation and polarization is essential for optimizing systems in telecommunications, imaging, and laser applications. Signal attenuation refers to the reduction in the intensity of a light beam as it passes through a medium or a device. This theory has been developed for any type of BS and is based on the constancy of the re ection coe cients R (or the transmission coe cient, where R + T = 1). The splitter is constructed by fusing together the two parallel bare fibers at one point. Arrangements of mirrors or prisms used as camera attachments to photograph stereoscopic image pairs with one lens and one exposure are sometimes called "beam splitters", but that is a misnomer, as they are. A lossless beam-splitter has certain (complex-valued) probability amplitudes for sending an incoming photon into one of two possible directions.
