By using a monolithically integrated dualdistributed feedback (DFB) laser chip attached to a photomixing

uni-travelling carrier photodiode (UTC-PD) with a THz

antenna, a single-channel THz photonic-wireless transmission

system with a net rate of 131 Gbit/s over a wireless distance of

10.7 m has been achieved

Carpintero, G

Chen, J

Hu, H

Jia, S

Kong, D

Lo, MC

Morioka, T

Oxenlowe, L

Ozolins, O

Pang, X

Popov, S

Udalcovs, A

Xiao, S

Yu, X

Zhang, L

English

UCL Discovery

XXX-X-XXXX-XXXX-X/XX/$XX.00 ©20XX IEEE Chip based THz emitter for ultra-high speed THz wireless communication Hao Hu1, Shi Jia1, Mu-Chieh Lo2,7, Lu Zhang3,6, Oskars Ozolins4, Aleksejs Udalcovs4, Deming Kong1, Xiaodan Pang3, Xianbin Yu5, Shilin Xiao6, Sergei Popov3, Jiajia Chen3, Guillermo Carpintero2, Toshio Morioka1, Leif K. Oxenløwe1  1DTU Fotonik, Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark  2 Universidad Carlos III de Madrid, 28911 Leganés, Madrid, Spain  3KTH Royal Institute of Technology, 164 40 Kista, Sweden 4NETLAB, Research Institutes of Sweden AB, 164 25 Kista, Sweden 5College of Information Science and EE, Zhejiang University, Hangzhou 310027, China 6School of SE-IEE, Shanghai Jiao Tong University, Shanghai 200240, China 7Currently with University College London, London WC1E 7JE,UK Author e-mail address: huhao@fotonik.dtu.dk; shijai@fotonik.dtu.dk; guiller@ing.uc3m.es; xiaodan@kth.se  Abstract— By using a monolithically integrated dual-distributed feedback (DFB) laser chip attached to a photomixing uni-travelling carrier photodiode (UTC-PD) with a THz antenna, a single-channel THz photonic-wireless transmission system with a net rate of 131 Gbit/s over a wireless distance of 10.7 m has been achieved. Keywords— THz wireless communication, generic foundry, DFB laser, frequency comb, UTC-PD I. INTRODUCTION THz wireless communication (TWC) with large available bandwidths is a promising technique to fill the data rate gap between fiber optic networks and wireless networks. Therefore, the exploration of wireless communication in the THz band (>300 GHz) is a time-being necessity and can pave the way towards 5G networks and beyond 5G networks. Using photonic technologies is a promising path to generate high-quality THz signals to carry 100s of Gbit/s of data, and additionally has the great advantage of being compatible with the fiber-optic network, providing a way to distribute wireless-on-fiber over long distances [1]. Apart from the mobile data streams, many other bandwidth-hungry applications are expected to be facilitated by the TWC, such as supercomputing, ultra-fast intra-board interconnection, fast restoration of link connections in disaster areas and so on [2].   Fig.1. The comparison of the normalized transmitter THz power of the reported demonstrations with long reach. In terms of THz wireless communications, the carrier frequencies ranging from 350-910 GHz have been recommended for indoor communications with the 10-100 m range [3]. Extensive research has been conducted to achieve high data rates transmissions at these frequencies [4-19]. Using photonic schemes, high data rates have been achieved by frequency division multiplexing techniques often yielding data rates of 100 Gbit/s and above. However, these multiplexing techniques based on bulky components increase the system cost and complexity. Single-channel THz wireless transmission with a data rate beyond 100 Gbit/s has recently been demonstrated over a very short distance. Figure 1 shows reported long-distance (>10 m) THz wireless transmission in different THz bands revealing the relation of data rate, distance and emitted THz power [17, 19-21].  II. INTEGRATED DUAL-DFB LASERS BASED THZ TRANSMITTER Photonic integrated circuits (PICs) based THz synthesizers have the advantages of low cost, small footprint and low power consumption. Moreover, facilitated by continuous development of semiconductor fabrication technologies, the open-access InP generic foundry photonic integration approach has allowed active and passive components to be monolithically integrated on the same substrate [22]. The integrated dual-DFB lasers are fabricated in a generic foundry approach. Two DFB lasers are placed in parallel and combined through a MMI coupler. Each DFB laser is controlled with heater current and injection current. Each standardized DFB laser building block contains a GSG transmission coplanar waveguide (CPW) along with an internal heater for thermo-optic tuning. Injection currents are injected onto the GSG CPWs, and heater currents are fed onto the heater pads. The wavelength spacing between the two continuous waves (CWs) is controllable within the range of 0-10.7 nm, resulting in a continuously tunable beat note from microwave to THz frequencies (up to ~1.4 THz).  III. CHIP-BASED THZ WIRELESS COMMUNICATION SYSTEM Figure 2 shows the schematic of the chip-based THz wireless communication system. Two CWs with a frequency spacing of 408 GHz are generated by the dual-DFB laser chip, which are injection locked by a mode-locked laser based frequency comb, and thus these two CW tones are phase coherent. One tone is used as an optical local oscillator (LO) for heterodyne mixing in order to generate the THz wave. The other tone is used to carry data and launched into an in-phase (I) and quadrature (Q) optical modulator (IQM). The modulated 16-QAM-OFDM (quadrature amplitude modulation-orthogonal frequency-division multiplexing) optical signal and the optical LO are combined before launching into the broadband UTC-PD. At the output of the UTC-PD, a THz signal with carrier frequency centered at 408 GHz is generated and emitted into a 10.7-m line-of-sight (LOS) wireless link, as shown in Fig. 2(d). A pair of THz lenses with a 100-mm diameter and 200-mm focus length is used to collimate the THz beam. At the receiver, the THz signal is down-converted to an intermediate frequency (IF) by a sub-harmonic Schottky mixer. The IF signal is digitally sampled by a 160 GSa/s real-time digital sampling oscilloscope (DSO). The digital signals are processed and analyzed offline with a digital signal processing (DSP) routine. The BER below the FEC threshold (2.7 e-2, 20%-OH) has been achieved for the 16-QAM-OFDM signal with a total bandwidth of 44.43 GHz, which corresponds to a gross bit rate of 157.46 Gbit/s (subtracting the pilot overhead) and a net rate of 131.21 Gbit/s after subtracting the FEC overhead. ACKNOWLEDGEMENTS We would like to thank the support by the EU H2020 Marie Sklodowska-Curie grant agreement no. 713683 (COFUNDfellowsDTU), the EU H2020 Marie Skłodowska-Curie Grant agreement no. 642355 FiWiN5G, the Danish center of excellence CoE SPOC under Grant DNRF123, the Villum young investigator program grant of 2MAC and the China Postdoctoral Science Foundation under Grant 2017M611990, the Swedish Research Council (VR), the Swedish Foundation for Strategic Research (SSF), Göran Gustafsson Foundation, the Swedish ICT TNG, the EU H2020 MCSA-IF Project NEWMAN (#752826), VINNOVA funded SENDATE-EXTEND and SENDATE-FICUS, National Natural Science Foundation of China (#61331010, 61722108, 61775137, 61671212). REFERENCES [1] Shams, H. et al., “Photonics, fiber and THz wireless communication.” Optics&Photonics News 28.3 (2017): 24-31.  [2] Song, H. J. et al., “Present and future of terahertz ommunications.” IEEE Transactions on Terahertz Science and Technology 1.1 (2011): 256-263.  [3] Nagatsuma, T. et al., "Advances in terahertz communications accelerated by photonics." Nature Photonics 10.6 (2016): 371-379.  [4] Shi Jia et al., “THz photonic wireless links with 16-QAM modulation in the 375-450 GHz band”, Optics Express[J], 2016, 24(21): 23777-23783  [5] Shi Jia et al., “THz wireless transmission systems based on photonic generation of highly pure beat-notes”, IEEE Photonics Journal[J], 2016, 8(5): 7905808  [6] Shi Jia et al., “120 Gbit/s multi-channel THz wireless transmission and THz receiver performance analysis”, IEEE Photonics Technology Letters[J], 2017, 29(3): 310-313 [7] Shi Jia et al., “80 Gbit/s 16-QAM multicarrier THz wireless communication link in the 400 GHz band”, 2016 European Conference on Optical Communication(ECOC), (2016), paper W.1.E.5 [8] Shi Jia et al., “Experimental analysis of THz receiver performance in 80 Gbit/s communication system”, 41st International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THZ 2016), (2016), paper H5P.17.02 [9] Xianbin Yu et al., “160 Gbit/s photonics wireless transmission in the 300-500 GHz band”, APL Photonics[J], 2016, 1(8): 081301-1-6  [10] Xianbin Yu et al., “THz Photonics-Wireless Transmission of 160 Gbit/s Bitrate”, 21st Optoelectronics and Communications Conference/International Conference on Photonics in Switching 2016 (OECC/PS 2016), paper post dead-line [11] Xiaodan Pang et al.,  “260 Gbit/s Photonic-Wireless Link in the THz Band”, 2016 IEEE Photonics Conference, 29th Annual Conference of the IEEE Photonics Society (IPC 2016), paper post dead-line [12] Shi Jia et al., “A unified system with integrated generation of high-speed communication and high-resolution sensing signals based on THz photonics”, IEEE/OSA Journal of Lightwave Technology 36(19): 4549-4556, 2018 [13] Shi Jia et al., “0.4 THz photonic-wireless link with 106 Gb/s single channel bitrate”, IEEE/OSA Journal of Lightwave Technology 36(2): 610-616, 2018 [14] Kexin Liu et al,, “100 Gbit/s THz photonic wireless transmission in the 350-GHz band with extended reach ” , IEEE Photonics Technology Letters 30(11): 1064-1067, 2018 [15] Xiaodan Pang et al., “Single channel 106 Gbit/s 16QAM wireless transmission in the 0.4 THz band,” in Proc. Opt. Fiber Commun. Conf. (OFC), Los Angeles, CA, Mar. 2017, Paper Tu3B.5 [16] Leif K. Oxenløwe et al., “100s Gigabit/s THz communication”, in Conference on Lasers and Electro-Optics (CLEO), STu3D.1, May 2018, San Jose, USA [17] Shi Jia et al., “Integrated Dual-DFB Laser for 408 GHz Carrier Generation Enabling 131 Gbit/s Wireless Transmission over 10.7 Meters”, in Optical Fiber Communication Conference (OFC), San Diego, CA, Mar. 2019, Paper Th1C.2 [18] X. Li et al., “Photonics-aided 2×2 MIMO wireless terahertz-wave signal transmission system with optical polarization multiplexing,” Opt. Express, Vol. 25, p. 33236 (2017). [19]  J. Ma et al., "Channel Performance for Indoor and Outdoor Terahertz Wireless Links," APL Photon., Vol. 3, p. 051601 (2018). [20] T. Nagatsuma et al., "300-GHz-band Wireless Transmission at 50 Gbit/s over 100 Meters," Proc. IRMMW-THz, 1-2, Copenhagen (2016). [21] T. Harter et al., "110-m THz Wireless Transmission at 100 Gbit/s Using a Kramers-Kronig Schottky Barrier Diode Receiver," Proc. ECOC, PDP 1-3, (2018). [22] Mu-Chieh Lo et al., "Foundry-Fabricated Dual-DFB PIC Injection-Locked to Optical Frequency Comb for High-Purity THz Generation", in Optical Fiber Communication Conference (OFC), San Diego, CA, Mar. 2019, Paper W1B.3    Fig. 2. Experimental configuration of 131.21 Gbit/s single-channel photonic-wireless 16-QAM-OFDM transmission system over 10.7 m: (a) On-chip optical LO and carrier generation with injection locking. (b) Optical modulation and LO combining. (c) The structure of the DSP routine. (d) The picture of the actual THz link. (e) THz emitting, transmission and reception. 

TuB4.1-chip based thz emitter for ultra-high speed THz wireless communication (Invited)

https://discovery.ucl.ac.uk/id/eprint/10083228/3/Lo%20Chip%20based%20THz%20emitter%20for%20%20ultra-high%20speed%20THz%20wireless%20communication%20-%20final.pdf

TuB4.1-chip based thz emitter for ultra-high speed THz wireless communication (Invited)

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