This is an attenuator that directly coats a metal absorption film or reflection film on the end face of the optical fiber or the glass substrate to attenuate the light energy. Commonly used evaporated metal films include: Al film, Ti film, Cr film, W film, etc. The three basic types of gap loss are angular misalignment loss, lateral offset loss, and longitudinal displacement loss. The attenuator circuit will allow a known source of power to be reduced by a predetermined factor, which is usually expressed as decibels. Its primary function is to control the strength of light to prevent signal overload, which can lead to system damage. An optical attenuator, or fiber optic attenuator, is a device used to reduce the power level of an optical signal, either in free space or in an optical fiber. Key requirements include minimal effect on the beam profile, low wavelength and polarization dependence, and sufficient power handling capability. Different types of attenuators operate.
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