Terahertz wireless communications based on photonics technologies

Abstract

There has been an increasing interest in the application of terahertz (THz) waves to broadband wireless communications. In particular, use of frequencies above 275 GHz is one of the strong concerns among radio scientists and engineers, because these frequency bands have not yet been allocated at specific active services, and there is a possibility to employ extremely large bandwidths for ultra-broadband wireless communications. Introduction of photonics technologies for signal generation, modulation and detection is effective not only to enhance the bandwidth and/or the data rate, but also to combine fiber-optic (wired) and wireless networks. This paper reviews recent progress in THz wireless communications using telecom-based photonics technologies towards 100 Gbit/s.

Recent Progress and Future Prospect of Photonics-Enabled Terahertz Communications Research

“…This bit rate might be the highest achievable when we consider bandwidths of all the electronic components such as amplifiers including our BER test equipment. By using a polarization multiplexing scheme with wire-grid polarizers, it is possible to double the bit rate to 100 Gbit/s [27].…”

“…Particularly, above 275 GHz, there is a possibility to employ extremely large bandwidths for "radio" communications, since these frequency bands have not yet been allocated at specific active services, and standardization efforts have been becoming very active [1], [7]. Figure 1 summarizes experimentally achieved data rates of over 1 Gbit/s by transmission experiments with over-100-GHz carrier frequencies at 100-150 GHz [8]- [14], 200-250 GHz [15]- [21], 300-350 GHz [22]- [31], 400-450 GHz [23], [32], 500-700 GHz [27], [33]- [35]. Data points with triangles are demonstrations using electronicsbased transmitter, while data points with circles are achieved by photonics-based ones.…”

Broadband terahertz metamaterial absorber based on simple multi-ring structures

“…5 Although a lot of efforts have been made in the THz, the demands for highperformance THz devices are still unsatisfied for the limitations of natural materials. Metamaterials are candidates for developing high-performance terahertz devices owing to the strong interaction between electromagnetic wave and artificial structures.…”

THz photonic wireless links with 16-QAM modulation in the 375-450 GHz band

“…Several wireless propagation demonstrations in higher frequency bands have been reported, such as 11 Gbit/s on-off keying (OOK) data wireless transmission at 100 GHz carrier frequency [16], a 40 Gbit/s wireless link at 300 GHz based on OOK data modulation and direct detection [17], real-time 50 Gbit/s OOK 300 GHz wireless transmission at over 20 m distance [18], a wireless OOK link operating at a carrier frequency of 220 GHz with a data rate of 25 Gbit/s [19], 24 Gbit/s amplitude shift keying (ASK) data wireless transmission at 300 GHz using a uni-travelling carrier photodiode (UTC-PD) emitter and a Schottky barrier diode detector [20], 200 GHz multicarrier wireless transmission using a quadrature phaseshift keying (QPSK) baseband signal and a gain-switched laser comb source [21], 25 Gbit/s QPSK hybrid fiber-wireless transmission in the W-Band (75-110 GHz) with a remote antenna unit for in-building wireless networks [22], and 60 Gbit/s QPSK wireless transmission with real-time capable detection at 400 GHz carrier [23]. Furthermore, spectrally efficient quadrature amplitude modulation (QAM) signals have also been implemented, such as 100 Gbit/s and 40 Gbit/s 16-QAM signals in the 75-110 GHz band [24,25] and singleinput/single-output (SISO) QPSK, 8-QAM and 16-QAM signals at 237.5 GHz [26,27].…”