Patent attributes
A phase coder-decoder for quantum key distribution including a beam splitter, two reflecting devices with an orthogonal rotation of polarization optically coupled with the beam splitter via two arms, and a phase modulator provided on one of the two arms. The reflecting devices including a polarization beam splitter having an input and two output ports, and coupled to a corresponding arm via the input port, the output ports optically coupled to each other via a polarization maintaining optical fiber twisted by 90 degrees such that optical pulses output by the output ports are coupled to an axis of the polarization maintaining optical fiber for transmission. The phase coder-decoder is configured to stably perform interference on input optical pulses with an arbitrary polarization state for coding and decoding purpose.