Loss testing, as a necessary testing item of optical splitters, can be done by using an optical power meter and light source. Before discussing the details of splitter loss testing, here is a fact that we should know about it. Whether an optical splitter is combining signals in the upstream direction or dividing signals in the downstream direction, it still introduces the same attenuation to an optical. SPLITTER ATTENUATION DEVICE BA-1 B. With the use of an additional preattenuator beam splitter, the attenuation range can be extended to. So for this simple 1X2 splitter, how do we test it? Simply follow the same directions for a double-ended loss test. Splitters are essential when you want one fiber line from a central office (like an ISP's headend or data center) to serve multiple homes or businesses.