A SDH receiver which comprises a first polarization beam splitter 11, a second polarization beam splitter 13, a first separator 15, a second separator 17, a third separator 19, a fourth separator 21, a first 90-degree polarization rotor 23, a second 90-degree polarization rotor 25, a first hybrid detector 31, a second hybrid detector 33, a third hybrid detector 35, a fourth hybrid detector 37, and a signal processor 39.