| 1. |
- Deng, Qiuzhuo, et al.
(författare)
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Quantum Noise Secured Terahertz Communications
- 2023
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Ingår i: 2023 Optical Fiber Communications Conference and Exhibition (OFC).
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Konferensbidrag (refereegranskat)abstract
- The quantum noise based terahertz signal encryption scheme is proposed, a 16 Gbits-1 secure terahertz communication system at 300 GHz with the optical communication realms is demonstrated, taking a significant step toward high-security wireless communications.
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| 2. |
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| 3. |
- Fan, Yuchuan, et al.
(författare)
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EVM Estimation for Performance Monitoring in Coherent Optical Systems : An Approach of Linear Regression
- 2022
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Ingår i: Optics InfoBase Conference Papers. - : Optica Publishing Group (formerly OSA). - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrate the effectiveness of a simple linear regression scheme for optical performance monitoring when applied after modulation format identification. It outperforms the FFNN-based benchmark scheme providing 0.2% mean absolute error for EVM estimation., © 2022 The Author(s)
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| 4. |
- Fan, Yuchuan, et al.
(författare)
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Feedforward Neural Network-Based EVM Estimation : Impairment Tolerance in Coherent Optical Systems
- 2022
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers Inc.. - 1077-260X .- 1558-4542. ; 28:4
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Tidskriftsartikel (refereegranskat)abstract
- Error vector magnitude (EVM) is commonly used for evaluating the quality of m-ary quadrature amplitude modulation (mQAM) signals. Recently proposed deep learning techniques for EVM estimation extend the functionality of conventional optical performance monitoring (OPM). In this article, we evaluate the tolerance of our developed EVM estimation scheme against various impairments in coherent optical systems. In particular, we analyze the signal quality monitoring capabilities in the presence of residual in-phase/quadrature (IQ) imbalance, fiber nonlinearity, and laser phase noise. We use feedforward neural networks (FFNNs) to extract the EVM information from amplitude histograms of 100 symbols per IQ cluster signal sequence captured before carrier phase recovery. We perform simulations of the considered impairments, along with an experimental investigation of the impact of laser phase noise. To investigate the tolerance of the EVM estimation scheme to each impairment type, we compare the accuracy for three training methods: 1) training without impairment, 2) training one model for all impairments, and 3) training an independent model for each impairment. Results indicate a good generalization of the proposed EVM estimation scheme, thus providing a valuable reference for developing next-generation intelligent OPM systems.
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| 5. |
- Han, M., et al.
(författare)
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Deep Reservoir Computing for 100 Gbaud PAM6 IM/DD Transmission Impairment Mitigation
- 2023
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Ingår i: Opt. Fiber Commun. Conf. Exhib., OFC - Proc.. - : Institute of Electrical and Electronics Engineers Inc..
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Konferensbidrag (refereegranskat)abstract
- We experimentally evaluate a deep Reservoir Computing (RC)-based post-equalization for 100 Gbaud PAM6 IM/DD transmissions. It achieves ∼1 dB higher sensitivity than DFE, and ∼50% implementation complexity reduction compared with the conventional RC configuration.
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| 6. |
- Han, Mengyao, et al.
(författare)
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Optical amplification-free deep reservoir computing-assisted high-baudrate short-reach communication
- 2023
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Ingår i: Optics Letters. - : Optica Publishing Group (formerly OSA). - 0146-9592 .- 1539-4794. ; 48:8, s. 2122-2125
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Tidskriftsartikel (refereegranskat)abstract
- An optical amplification-free deep reservoir computing (RC)-assisted high-baudrate intensity modulation direct detection (IM/DD) system is experimentally demonstrated using a 100G externally modulated laser operated in C-band. We transmit 112 Gbaud 4-level pulse amplitude modulation (PAM4) and 100 Gbaud 6-level PAM (PAM6) signals over a 200-m single-mode fiber (SMF) link without any optical amplification. The decision feedback equalizer (DFE), shallow RC, and deep RC are adopted in the IM/DD system to mitigate impairment and improve transmission performance. Both PAM transmissions over a 200-m SMF with bit error rate (BER) performance below 6.25% overhead hard-decision forward error correction (HD-FEC) threshold are achieved. In addition, the BER of the PAM4 signal is below the KP4-FEC limit after 200-m SMF transmission enabled by the RC schemes. Thanks to the use of a multiple-layer structure, the number of weights in deep RC has been reduced by approximately 50% compared with the shallow RC, whereas the performance is comparable. We believe that the optical amplification-free deep RC-assisted high-baudrate link has a promising application in intra-data center communications.
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| 7. |
- Lyu, Z., et al.
(författare)
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Preamble-Free Synchronization Based on Dual-chirp Waveforms for Photonic THz-ISAC
- 2024
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 42:8, s. 2657-
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Tidskriftsartikel (refereegranskat)abstract
- The integrated sensing and communication (ISAC) systems based on the linear frequency modulation (LFM) waveforms have attracted substantial attention. However, existing routines suffer from additional synchronization preamble overhead, which limits both communication and sensing performance. This work, using the dual-chirp with opposite slopes, exploits a preamble-free synchronization scheme for the LFM-based ISAC. We first theoretically analyze the quasi-orthogonal property of the proposed dual-chirp LFM waveform and derive its achievable communication rate and range ambiguity function. A photonics-assisted proof-of-concept ISAC experiment is conducted in the 300 GHz frequency band, achieving a 20 Gbps data rate with a distinguished peak sidelobe ratio (PSLR) of up to 29.2 dB and 1.5 cm range resolution. More importantly, less than 0.5% synchronous power overhead is needed in our scheme. In addition, the performance trade-off induced by the data rate and amplitude ratio is validated in the experiment, which is in line with our theoretical analysis. Therefore, the proposed scheme provides a promising solution for synchronizing LFM-based future ISAC systems.
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| 8. |
- Ostrovskis, A., et al.
(författare)
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106.25 Gbaud On-Off Keying and Pulse Amplitude Modulation Links Supporting Next Generation Ethernet on Single Lambda
- 2024
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 42:4, s. 1272-
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Tidskriftsartikel (refereegranskat)abstract
- Development of Data Center based computing technology require energy efficient high-speed transmission links. This leads to optical amplification-free intensity modulation and direct detection (IM/DD) systems with low complexity equalization compliant with IEEE standardized electrical interfaces. Switching from on-off keying to multi-level pulse amplitude modulation would allow to reduce lane count for next generation Ethernet interfaces. We characterize 106.25 Gbaud on-off keying, 4-level and 6-level pulse amplitude modulation links using two integrated transmitters: O-band directly modulated laser and C-band externally modulated laser. Simple feed forward or decision feedback equalizer is used. We demonstrate 106.25 Gbaud on-off keying links operating without forward error correction for both transmitters. We also show 106.25 Gbaud 4-level and 6-level pulse amplitude modulation links with performance below 6.25% overhead hard-decision forward error threshold of 4.5×10-3. Furthermore, for EML-based transmitter we achieve 106.25 Gbaud 4-level pulse amplitude modulation performance below KP-FEC threshold of 2.2×10-4. That shows that we can use optics to support (2x)100 Gbps Ethernet on single lambda at expense of simple forward error correction.
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| 9. |
- Ostrovskis, A., et al.
(författare)
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240/160 Gbaud OOK Silicon Photonics MZM/RRM Transmitters for Short-Reach Applications
- 2023
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Ingår i: IEEE International Conference on Group IV Photonics GFP. - : IEEE Computer Society. - 9781665486552
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a record 240 Gbaud on-off keying, 150 Gbaud 4-level pulse amplitude modulation, and 100 Gbaud 6-level pulse amplitude modulation SiP MZM-based transmitter with performance below the 6.25% overhead HD-FEC threshold. We also show a 160 Gbaud on-off keying SiP RRM-based transmitter.
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| 10. |
- Ozolins, O., et al.
(författare)
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Cascadability of silicon microring resonators for 40-Gbit/s OOK and DPSK optical signals
- 2012
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Ingår i: 2012 Asia Communications and Photonics Conference (ACP). ; , s. 1-3
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Konferensbidrag (refereegranskat)abstract
- The cascadability of a single silicon micro-ring resonator for CSRZ-OOK and CSRZ-DPSK signals is experimentally demonstrated at 40 Gbit/s for the first time. Error-free performance is obtained for both modulation formats after 5 cascaded resonators.
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| 11. |
- Ozolins, Oskars, et al.
(författare)
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Error-Free 108 Gbps On-Off Keying Link for Optical Interconnect Applications
- 2022
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Ingår i: 2022 European Conference on Optical Communication, ECOC 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9781957171159
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Konferensbidrag (refereegranskat)abstract
- We demonstrate an error-free 108 Gbps OOK link using a C-band externally modulated laser with 3.3 dBm of modulated output power and an O-band directly modulated laser with 7.3 dBm of modulated output power. This paves the way forward for high-speed optical interconnects without FEC.
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| 12. |
- Pang, Xiaodan, Dr., et al.
(författare)
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200 Gb/s Unamplified IM/DD Transmission over 20-km SMF with an O-band Low-Chirp Directly Modulated Laser
- 2022
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Ingår i: 2022 European Conference on Optical Communication, ECOC 2022. - : Institute of Electrical and Electronics Engineers Inc.. - 9781957171159
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Konferensbidrag (refereegranskat)abstract
- 200 Gb/s IM/DD transmission over 20-km SMF is demonstrated without any optical amplifiers, achieving BER below the 6.25%-overhead HD-FEC limit, enabled by a broadband and high-power DML with low-complexity digital equalizations.
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| 13. |
- Pang, Xiaodan, Dr., et al.
(författare)
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Directly modulated quantum cascade laser and its application in free-space communications
- 2021
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 9781510646377
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Konferensbidrag (refereegranskat)abstract
- In this report, we summarize our recent achievements in free-space communications in the mid-infrared (MIR) region enabled by directly modulated quantum cascaded laser (QCL) at 4.65 μm (∼65 THz). We have experimentally demonstrated a multigigabit free-space transmission link in the lab environment with the QCL operating at room temperature. The QCL chip is mounted on a commercial QCL mount with a water-cooled Peltier element. Multilevel modulation formats at different baud rates are generated and combined with the laser driving current at a custom-made bias-Tee to drive and modulate the QCL. A commercial mercury cadmium telluride (MCT, HgCdTe) photovoltaic (PV) MIR detector with a built-in trans-impedance amplifier was used to receive the MIR free-space signal. With the receiver to be the bottleneck of the system bandwidth, the end-To-end 3-dB bandwidth was measured to be around 320 MHz, and the 6-dB bandwidth was around 450 MHz. We have successfully demonstrated up to 6 Gbps free space transmission with multilevel modulation formats, assisted with effective digital equalization techniques despite the limited bandwidth..
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| 14. |
- Pang, Xiaodan, Dr., et al.
(författare)
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Free-Space Transmissions in the Upper- and Lower-THz Bands Assisted with Photonics
- 2021
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Ingår i: 2021 European Conference on Optical Communication (ECOC). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- We report our recent studies in photonics-assisted free-space transmissions in both the lower (0.3-0.5 THz) and upper- (~64.5 THz) terahertz bands. We adopt the hybrid electro-optical approach for the lower-THz signal transmission, whereas a directly modulated quantum cascade laser is used for the upper-THz band.
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| 15. |
- Puerta, Rafael, et al.
(författare)
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5G/NR Conformance Testing of Analog Radio-overfiber Fronthaul Links
- 2022
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Ingår i: 2022 IEEE International Topical Meeting on Microwave Photonics, MWP 2022 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781665421218
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Konferensbidrag (refereegranskat)abstract
- Foreseen requirements and use cases of future beyond fifth-generation (B5G) and sixth-generation (6G) mobile networks have shown that current mobile networks implementations must be reconsidered. Analog radio-over-fiber (ARoF) is a prospective solution for future mobile fronthaul of certain applications where current solutions fall short to fulfill future demands on bandwidth and power consumption. This paper provides a complete New-Radio (NR) conformance testing of ARoF fronthaul links in full accordance with the 3rd Generation Partnership Project (3GPP) technical specifications. We experimentally verified that the adjacent channel leakage power ratio (ACLR) and the error vector magnitude (EVM) transmitter requirements are fulfilled validating ARoF links as a suitable solution for next-generation mobile fronthaul. Wireless transmissions results are also provided.
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| 16. |
- Puerta, Rafael, et al.
(författare)
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NR Conformance Testing of Analog Radio-over-LWIR FSO Fronthaul link for 6G Distributed MIMO Networks
- 2023
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Ingår i: Opt. Fiber Commun. Conf. Exhib., OFC - Proc.. - : Institute of Electrical and Electronics Engineers Inc..
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Konferensbidrag (refereegranskat)abstract
- We experimentally test the compliance with 5G/NR 3GPP technical specifications of an analog radio-over-FSO link at 9 μm. The ACLR and EVM transmitter requirements are fulfilled validating the suitability of LWIR FSO for 6G fronthaul. © 2023 The Author(s).
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| 17. |
- Salgals, Toms, et al.
(författare)
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Silica Microsphere WGMR-Based Kerr-OFC Light Source and Its Application for High-Speed IM/DD Short-Reach Optical Interconnects
- 2022
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 12:9, s. 4722-
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Tidskriftsartikel (refereegranskat)abstract
- Kerr optical frequency combs (OFCs) based on silica microsphere whispering gallery mode resonator (WGMR) have various applications where they are used as a light source. For telecommunication purposes, WGMR-based Kerr-OFC comb generators can be physically realized using silica microsphere resonators and can be used to replace multiple laser arrays. In such a realization, these novel light sources have the potential to demonstrate an attractive solution for intra-datacenter interconnects (DCI). In this paper, we show an experimental demonstration of a silica microsphere WGMR-based Kerr OFC light source where newly generated 400 GHz spaced carriers together with powerful linear equalization techniques, such as a linear symbol-spaced adaptive decision-feedback equalizer (DFE) with feed-forward (FF) and feedback (FB) taps, provide an alternative to individual lasers ensuring low-cost and low-complexity IM/DD scheme for the transmission of NRZ-OOK modulated signals at data rates up to 50 Gbps/lambda over 2 km SMF link. Finally, we demonstrate a record 50 Gbps per lambda transmission of NRZ-OOK modulated signals with a novel silica microsphere WGMR-based Kerr-OFC as a light source operating in the optical C-band, surpassing the previously demonstrated data rate record by five times.
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| 18. |
- Udalcovs, Aleksejs, et al.
(författare)
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Power efficiency of WDM networks using various modulation formats with spectral efficiency limited by linear crosstalk
- 2014
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 318, s. 31-36
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Tidskriftsartikel (refereegranskat)abstract
- Small channel spacing in WDM systems offers very good spectral efficiency, but may reduce the transparent optical reach because of interchannel crosstalk. In turn, an increase in the network power consumption can be expected, due to the need for signal regeneration. This paper explores the trade-off between spectral efficiency, transparent optical reach, and power consumption. The results confirm that using the most energy efficient transponder (i.e., in terms of W/bps) does not always guarantee the lowest overall network power consumption. This is especially true over long point-to-point distances (i.e., multiple transmission fiber spans) where, in order to ensure stringent quality of transmission levels together with high spectral efficiency, the optical signal needs to be regenerated many times.
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| 19. |
- Zhang, Lu, et al.
(författare)
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Hybrid fiber–THz fronthaul supporting up to 16384-QAM-OFDM with the delta-sigma modulation
- 2022
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Ingår i: Optics Letters. - : Optica Publishing Group (formerly OSA). - 0146-9592 .- 1539-4794. ; 47:17, s. 4307-4310
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Tidskriftsartikel (refereegranskat)abstract
- With the progress of high-capacity radio access networks, ultra-dense small cells are rapidly being deployed in urban areas. As a result, the deployment of a large number of optical fibers in urban areas becomes a severe issue. In this Letter, we propose a hybrid fiber–terahertz (THz) mobile fronthaul system supporting flexible and high-order wireless signal transmission with the delta-sigma modulation. The photonic THz transmission is used as the seamless extension of fiber-based fronthaul in small cells. A 20-Gbit/s digital fiber–THz fronthaul system is experimentally demonstrated to validate the proposed scheme, with 10-km optical fiber transmission and 300-GHz wireless relay. Carrier aggregation of up to 10 40-MHz and 60-MHz 5G-new radio (5G-NR) channels at the radio carrier frequency of 3.9 GHz is reported. The design of quantization noise suppressed delta-sigma modulation enables the system to transmit orthogonal frequency division multiplexing (OFDM) modulation up to 16384 order quadrate amplitude modulation (QAM) mapping with the error vector magnitude (EVM) below 0.5%.
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| 20. |
- Zhang, L., et al.
(författare)
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Quantum Noise Secured Terahertz Communications
- 2023
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers Inc.. - 1077-260X .- 1558-4542. ; 29:5
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Tidskriftsartikel (refereegranskat)abstract
- The terahertz communications display an important role in high-speed wireless communications, the security threat from the eavesdroppers in the terahertz communications has been gaining attention recently. The true randomness in the physical layer can ensure one-time-pad encryption for secured terahertz communications, however, physical layer security schemes like the quantum key distribution methods suffer from device imperfections that limit the desirable signal rate and link distance. Herein, we present the quantum noise secured terahertz wireless communications with photonic terahertz signal generation schemes. With the high-order diffusion algorithms, the signal is masked by the quantum noise ciphers to the eavesdroppers and cannot be detected because the inevitable randomness by quantum noise measurement will cause physical measurement errors. In the experiment, we demonstrate 16 Gbits-1 quantum noise secured terahertz wireless communications with the conventional optical communication realms and devices, operating at 300 GHz terahertz frequency. This quantum noise secured terahertz communication approach is a significant step toward high-security wireless communications.
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