Publications by authors named "Fumio Futami"

4 Publications

  • Page 1 of 1

Ultra-long-haul digital coherent PSK Y-00 quantum stream cipher transmission system.

Opt Express 2021 Mar;29(7):10451-10464

A record-long 10,118-km fiber transmission with physical layer encryption is demonstrated utilizing a Y-00 cipher based on signal masking by quantum (shot) noise. The Y-00 cipher enables symmetric-key data encryption to ensure the security of the physical layer of optical communications. Irreducible secrecy without significant negative impact on transmission performance is achieved by the synergistic effect of combining seed-key-based high-order modulation and truly random shot noise inevitable in optical detection. This paper reports a comprehensive study of applying a phase-shift-keying (PSK) Y-00 cipher for ultra-long haul fiber transmission. Theoretical analysis shows that security-enhanced transmission over transoceanic-distance (>10,000 km) fiber is feasible when the quadrature PSK data signal is encrypted by converting to a PSK signal with 2 levels. Subsequently, 10,118-km standard single-mode fiber transmission of 48-Gbit/s line-rate dual-polarization PSK Y-00 cipher with 2 levels is experimentally demonstrated. An adequate signal quality above the Q-factor threshold of soft decision forward error correction is achieved together with sufficient signal masking by shot noise, yielding balanced transmission performance and high security in an ultra-long-haul PSK Y-00 cipher transmission system.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.418302DOI Listing
March 2021

Experimental demonstration of a 4,294,967,296-QAM-based Y-00 quantum stream cipher template carrying 160-Gb/s 16-QAM signals.

Opt Express 2021 Feb;29(4):5658-5664

We demonstrate a 4,294,967,296-quadrature amplitude modulation (QAM) based Y-00 quantum stream cipher system carrying a 160-Gb/s 16-QAM signal transmitted over 320-km SSMF. The ultra-dense QAM cipher template is realized by an integrated two-segment silicon photonics I/Q modulator.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.405390DOI Listing
February 2021

Single-channel 48-Gbit/s DP PSK Y-00 quantum stream cipher transmission over 400- and 800-km SSMF.

Opt Express 2019 Sep;27(18):25357-25363

A record-large product of data rate and transmission distance in quantum-noise-assisted cipher systems for physical layer security of fiber-optic transmission was demonstrated. The cipher system is based on symmetric-key direct-data encryption utilizing signal masking by quantum (shot) noise. The encryption is achieved by 2-level phase randomization of quadrature phase-shift keying data signal, resulting in 48-Gbit/s dual polarization Y-00 cipher with 2 phase levels. Successful transmission of the Y-00 cipher over 400- and 800-km standard single-mode fibers was achieved without significant negative impact on transmission quality. The product of the data rate and distance was 40 Gbit/s (net rate) × 800 km = 32,000 Gbit/s·km. The system achieves masking of 217 phase levels by shot noise, which promises irreducible and unchanged security based on the quantum nature of coherent light.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.27.025357DOI Listing
September 2019

Digital coherent PSK Y-00 quantum stream cipher with 2 randomized phase levels.

Opt Express 2019 Jan;27(2):1071-1079

We report a 10-Gbaud fiber-optic cipher transmission system by using a phase-shift keying (PSK) Y-00 quantum stream cipher. The PSK Y-00 cipher is a symmetric-key direct data encryption technique based on extremely high-order random phase modulation using a pre-shared short key. Neighboring signal phases following encryption are masked by quantum (shot) noise, which provides security based on shot noise's inherent effects. To implement such a system, we utilize coarse-to-fine phase modulation with two cascaded phase modulators and digital decryption incorporated into digital signal processing (DSP) for intra-dyne coherent detection. We demonstrate 10-Gbaud PSK Y-00 cipher transmission over a 400-km standard single-mode fiber (SSMF). The coarse-to-fine phase modulation achieves 2 phase levels for signal masking by shot noise. The DSP with decryption realizes detection of the cipher without penalties. Masking 167 signal phase levels by shot noise is achieved at a bit-error ratio defined by a hard-decision forward-error correction threshold (3.8 × 10) in the transmissions over the 400-km SSMF.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.27.001071DOI Listing
January 2019