Intradyne coherent receiver with optical decryption for disaggregated PSK Y-00 cipher transceiver architecture

The Y-00 quantum stream cipher utilizes the effect of quantum noise on optical signals and realizes signal-level symmetric-key encryption to protect interception in optical communication. A transceiver architecture that disaggregates encryption/decryption and modulation/demodulation in the optical domain facilitates the migration of Y-00 cipher to current digital-coherent communication systems. This paper presents a polarization-diversity intradyne Y-00 coherent receiver where local oscillator light is modulated for decryption. Polarization-diversity optical decryption and detection are simultaneously achieved using a typical optical 90-degree hybrid circuit and a conventional polarization-sensitive electro-optic modulator. Penalty-less detection with the decryption is demonstrated in 5-Gbit/s PSK Y-00 cipher transmission over fiber and free-space links, facilitating the disaggregation of decryption and demodulation.