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Recently, remarkable efforts have been made in developing wireless communication systems at ultrahigh data rates, with radio frequency (RF) carriers in the millimeter wave (30–300 GHz) and/or in the terahertz (THz, >300 GHz) bands. Converged technologies combining both the electronics and the photonics show great potential to provide feasible solutions with superior performance compared to conventional RF technologies. However, technical challenges remain to be overcome in order to support high data rates with considerably feasible wireless distances for practical applications, particularly in the THz region. In this work, we present an experimental demonstration of a single-channel THz radio-over-fiber (RoF) system operating at 350 GHz, achieving beyond 100 Gbit/s data rate over a 10-km fiber plus a >20-m wireless link, without using any THz amplifiers. This achievement is enabled by using an orthogonal frequency division multiplexing signal with a probabilistic-shaped 16-ary quadrature amplitude modulation format, a pair of highly directive Cassegrain antennas, and advanced digital signal processing techniques. This work pushes the THz RoF technology one step closer to ultrahigh-speed indoor wireless applications and serves as an essential segment of the converged fiber-wireless access networks in the beyond 5G era.

A novel signal transmission technique termed subcarrier index-power modulated optical OFDM with superposition multiplexing (SIPM-OOFDM-SPM) is proposed and investigated, for the first time, in which SIPM automatically creates an information-carrying subcarrier power pattern via assigning a high (low) signal modulation format to a high (low) power subcarrier, whilst SPM passively adds different signal modulation format-encoded complex numbers and assigns the sum to a high power subcarrier. In comparison with conventional OOFDM, SIPM and SPM enable extra information to be conveyed in both the new subcarrier index-power dimension and the conventional subcarrier-information-carrying dimension. In this paper, extensive numerical explorations of SIPM-OOFDM-SPM performance characteristics are undertaken, based on which optimum transceiver design parameters are identified. For IMDD PON systems, it is shown that SIPM-OOFDM-SPM considerably improves the signal transmission capacity, link power budget and system performance tolerances to both chromatic dispersion and fiber nonlinearity. Index Terms-Orthogonal frequency division multiplexing, coding and decoding, digital signal processing and passive optical networks. I. INTRODUCTION ith the exponential data traffic growth associated with unprecedented emerging bandwidth-hungry network applications and services, recent years have seen extensive research interests in utilizing commercially available 10G-class optics to achieve 25Gb/s/λ intensity-modulation and direct-detection (IMDD) passive optical networks (PONs) equipped with desirable software defined networking (SDN) functionalities such as reconfigurability, flexibility, scalability and elasticity [1]-[3]. To deliver such a challenging task in a cost-effective approach, optical orthogonal frequency division Manuscript received May 22, 2016.

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We describe herein for the first time a full circuit model for electromagnetic pulse transmission in the Primary Test Stand (PTS)-the first TW class pulsed power driver in China. The PTS is designed to generate 8-10 MA current into a z-pinch load in nearly 90 ns rise time for inertial confinement fusion and other high energy density physics research. The PTS facility has four conical magnetic insulation transmission lines, in which electron current loss exists during the establishment of magnetic insulation. At the same time, equivalent resistance of switches and equivalent inductance of pinch changes with time. However, none of these models are included in a commercially developed circuit code so far. Therefore, in order to characterize the electromagnetic transmission process in the PTS, a full circuit model, in which switch resistance, magnetic insulation transmission line current loss and a time-dependent load can be taken into account, was developed. Circuit topology and an equivalent circuit model of the facility were introduced. Pulse transmission calculation of shot 0057 was demonstrated with the corresponding code FAST (full-circuit analysis and simulation tool) by setting controllable parameters the same as in the experiment. Preliminary full circuit simulation results for electromagnetic pulse transmission to the load are presented. Although divergences exist between calculated and experimentally obtained waveforms before the vacuum section, consistency with load current is satisfactory, especially at the rising edge.

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