▎ 摘　　要

NOVELTY - The optical filter has at least one graphene layer (602) disposed on an optical substrate (601). The number of graphene layers depends on desired optical absorption or transmission of filter and optical characteristic of the optical substrate. The optical substrate includes at least one layer of polymer, silicon carbide, sapphire, germanium or potassium bromide. The graphene layer is separately grown on growth substrate and subsequently transferred to optical substrate. The growth substrate contains silicon carbide. The optical substrate contains fused silica. USE - Broadband absorptive neutral density optical filter used in optical system (claimed) for attenuation of electromagnetic radiation such as terahertz radiation by uniform absorption over broad spectral bandwidth. Uses include but are not limited to extended time-exposure imaging, wide aperture imaging, increasing contrast in high-optical-brightness environments, protecting optical equipment from damage caused by excessive light, in optical systems in which temporal and spectral attributes of optical signals are coupled; and in optical systems that require precise adjustment of the light intensity and that require preservation of all parameters of input light e.g. spatial, temporal, spectral. Can also be used in safety equipment where light attenuation is desirable such as welding hoods, safety glasses. ADVANTAGE - Allows utilization in wide variety of optical assemblies and components since absorptance/transmittance of broadband absorptive neutral density optical filter is easily tuned by varying number of graphene layers disposed thereon. Allows use in applications having higher optical power since optical filter rapidly conducts the heat away from the absorbing region. Reduces number of elements within the optical system by allowing absorptive neutral density optical filter to be used with variety of optical substrates as well as wide range of optical devices. Obtains desired transmission for the filter by adjusting the number of graphene layers to account for optical properties of substrate. Provides simple and scalable variable attenuation by varying the number of layers of graphene used to form the filter. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an optical system. DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the formation of a broadband absorptive neutral density optical filter. Optical substrate (601) Graphene layer (602) Optical element (603)