600-GHz-Band Frequency-Division Multiplexing Communication with Silicon Unclad Diplexer

This paper presents a 600-GHz-band frequency-division multiplexing wireless communication using a silicon unclad diplexer. The designed diplexer has the advantages of lower loss and cost than the conventional metallic hollow waveguide in the 600-GHz and higher bands. It includes straight waveguides based on the effective medium approximation and a coupler comprised of unclad silicon wires, which provide a 3-dB bandwidth of 37 and 101 GHz and a crosstalk of -41 and -34 dB in the bar and cross directions, respectively. The parameters of the diplexer were optimized using 3-D full-wave simulation and validated with experimental results. Finally, we used the designed diplexer for frequency-division multiplexing in the 600-GHz band. The two channels operate simultaneously with carrier frequencies of 618 and 680 GHz. Both channels achieve a data-rate of 6 Gbit/s under error-free conditions and 12.5 Gbit/s at the forward error correction limit.