THz Optoelectronic 2-D Beam Steering Transmitter for Short-Range Communications

This paper reports on a THz optoelectronic beam steering transmitter for THz communications in WR3.4 frequency range. The tra nsmitter incorporates two commercially available UTC photodiode modules and an InP-based 2-D beam steering chip. In detail, this chip utilizes an array of three leaky-wave antennas driven by a beamforming network called CORPS to enable the 2-D beam steering using only two tuning elements. Experimentally, by sweeping the frequency between 0.26 and 0.32 THz, the beam steers from -12° to +33° in elevation direction. On the other hand, by tuning an optical delay line between ±0.84 ps, the THz beam changes the azimuth angle between -20° and +19°. Furthermore, data transmission of 2 Gbps over a 15 cm wireless distance is successfully demonstrated using the fabricated optoelectronic transmitter chip at various angles between 10° to 30° in elevation and 0° to 10° in azimuth. At all angles, the BER is below the hard-decision forward error correction limit of 3.8×10-3 when using a 4-QAM modulation. The highest SNR is found to be 14.84 dB at a point equivalent (El., Az.) of (20°, 5°).