Ultra-broadband shortwave polarization modulators for high-speed free-space quantum cryptography

Arnan Mitchell, M Austin, Paul Edwards, Le Nguyen Binh, Lam Anh Bui, Sana Mansoori, Wenn Jing Lai

    Research output: A Conference proceeding or a Chapter in BookConference contributionpeer-review


    Free-space quantum key exchanges between ground stations and low earth orbiting satellites will be characterized by high link losses, typically of the order of 30 dB or higher. These losses, together with the need to transmit weak Poissonian laser pulses containing on average substantially less than 0.1 photons per transmitted bit to preserve security, will result in exceedingly low channel efficiencies, typically of the order of 10-5. In order to achieve even a relatively modest secure key bit rate of 100 kbps, it will therefore often be necessary to key the transmitter at rates in excess of 10 Gbps. In this paper we outline several different methods of achieving such fast polarization keying including the use of dual drive Mach-Zehnder intensity modulators on lithium niobate in a hybrid fibre-guided modulator structures. We then propose a total integrated polarization keying structure in LiNbO3. We describe the fabrication and testing of such ultra-broadband polarization keyers suitable for use in high loss, short-wave free-space quantum key distribution systems employing silicon photon counters. We also indicate how these devices may be incorporated into quantum key satellite courier payloads and ground station terminals
    Original languageEnglish
    Title of host publicationProceedings of SPIE Volume 5161: Quantum Communications and Quantum Imaging
    EditorsRonald E Meyers, Yanhua Shih
    Place of PublicationUSA
    PublisherURSI Commission F Triennium Open Symposium
    Number of pages10
    ISBN (Print)9780819450340
    Publication statusPublished - 2004
    EventSPIE, Quantum Communications and Quantum Imaging - San Diego, California, United States
    Duration: 6 Aug 20038 Aug 2003


    ConferenceSPIE, Quantum Communications and Quantum Imaging
    Country/TerritoryUnited States


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