INTEGRATED OPTICAL LOCKER

An optical assembly includes an optical cavity; an output detector; a reference detector; and a plate beam splitter, wherein the plate beam splitter has a first face and a second face, and is configured to form, from an input beam: a first output beam, that passes through the optical cavity and impinges the output detector, a first reference beam that impinges on the reference detector, a second output beam parallel to the first output beam, and a second reference beam parallel to the first reference beam; one of the first output beam or the first reference beam is a reflection of the input beam in the first face of the plate beam splitter; the output detector is configured to exclude at least a portion of the second output beam; and the reference detector is configured to exclude at least a portion of the second reference beam.