Abstract: An optical signal processor having a monolithic prism supporting one or more channels, and constructed from a first glass block joined to a second glass block at a beam splitter interface. The monolithic prism has thin film beam splitters and filters (such as I and Q filters) either deposited directly on the prism or attached to it. The beam splitter interface, and the thin film beam splitters and filters are arranged relative to each other so that a portion of the return-ranging collimated encoded beam from an external optical sensor is reflected to all the filters. And detectors are connected over the filters to detect particular components of the collimated encoded beam which are passed through the respective filters.