Resonant tunneling diode-integrated terahertz transceiver module for wireless communications

Abstract

Terahertz bands enable ultra-broadband wireless communications but require compact, low-cost, and efficient transceiver modules. Conventional implementations based on metallic waveguides or silicon lenses suffer from high loss, bulkiness, and fabrication complexity. Here, we present a compact terahertz transceiver module enabled by a resonant tunneling diode (RTD) integrated with a photonic-electronic antenna chain. The RTD on InP is coupled to a modified Vivaldi antenna and an all-silicon effective-medium-clad waveguide, terminating in a rod antenna interfaced with a 3D-printed cyclic olefin copolymer lens. This architecture enables broadband directive radiation without matching networks or anti-reflection coatings. Packaged in a low-cost 3D-printed PLA enclosure, the module achieves realized gains of 28-33 dBi (E11x) and 30-33 dBi (E11y) across 220-330 GHz. As a receiver, it exhibits a noise voltage density of 5.6 x 10^-9 V/sqrt(Hz), a minimum noise equivalent power of 1.8 pW/sqrt(Hz), and an average responsivity of 6.8 kV/W. It supports error-free transmission up to 30 Gbit/s (OOK) and 80 Gbit/s (16-QAM) over 10 cm, and enables real-time uncompressed high-definition video streaming over 1 m. As a transmitter, it achieves error-free OOK transmission up to 12 Gbit/s at 332 GHz. These results demonstrate a promising terahertz transceiver architecture for 6G systems.

Figures (19)

• Figure 1: Schematic of the proposed RTD-based terahertz transceiver module. (a) Assembled module. (b) Disassembled module. Magnified view of the (c) EM-clad tapered rod antenna and (d) RTD chip. A 3D-printed COC substrate is inserted under the base of the package to support the RTD and dielectric antenna, as shown in (b).
• Figure 2: Schematic of RTD chip integrated with EM-clad dielectric waveguide. (a) Perspective view of the integration with RTD chip and the dielectric waveguide. (b) Eptitaxial quantum-well structure of RTD mesa diebold2016. (c) Design of RTD chip. (d) Profile of the modified Vivaldi antenna. The key dimensions of the RTD chip are given as: $L=20~\upmu$m, $g_{\rm{r}}=6~\upmu$m, $w_{\rm{s}}=12~\upmu$m, $l_{\rm{s}}=87.2~\upmu$m, $\theta_{s}=15^{\circ}$, $w_{\rm{p1}}=80~\upmu$m, $l_{\rm{p1}}=55~\upmu$m, $l_{\rm{p2}}=15~\upmu$m, $w_{\rm{p2}}=60~\upmu$m, $g_{\rm{p}}=16~\upmu$m, $w_{\rm{r}}=116~\upmu$m, $l_{\rm{r}}=212~\upmu$m. The duty cycle of the slit array is 50%. In CST simulations, the dielectric waveguide shown in (a) is terminated with a tapered structure to couple to the feeding hollow waveguide gao2019.
• Figure 3: Simulated results of RTD chip integrated with the dielectric waveguide. $E$-field distributions at (a) 275 GHz, (b) 300 GHz, (c) 400 GHz, and (d) 500 GHz. (e) Scattering ($S$)-parameters. (f) Coupling between the tapered structure and the hollow waveguide. All the $E$-field distributions are in linear scale and normalized by the same factor.
• Figure 4: Characteristics of air-clad tapered rod antenna fed by EM-clad waveguide. (a) Schematic of the antenna. Magnified view of (b) the hexagonal lattice of the air-silicon effective medium cladding, and (c) the rod antenna. (d) Simulated realized gain of the rod antenna versus taper length at 300 GHz. Simulated $E$-field distributions for (e) $E_{11}^{x}$ and (f) $E_{11}^{x}$ modes at 300 GHz. Simulated radiation patterns of a 3-mm tapered rod antenna for (g) $E_{11}^{x}$ and (h) $E_{11}^{x}$ modes at 300 GHz. The loss tangent of silicon adopted in the CST is $3\times10^{-5}$. Here, $a=100~\upmu$m, $d=90~\upmu$m.
• Figure 5: Air-clad tapered rod antenna coupled to an azimuthally symmetric elliptical lens. (a) Perspective view of the antenna architecture. (b) Profile of the elliptical lens. Simulated $E$-field distributions of the lens antenna for (c) $E_{11}^x$ mode with horizontal polarization ($xz$-plane) and (d) $E_{11}^y$ mode with vertical polarization ($yz$-plane) at 300 GHz. Simulated and measured reflection coefficients for (e) $E_{11}^x$ and (f) $E_{11}^y$ modes over WR-3.4 band (220--330 GHz). The reflection coefficients were measured using a Keysight VNA with VDI extenders spanning 220--330 GHz.