Lens-assisted quasi-optical THz transmitter employing antenna-integrated triple transit region photodiodes

In this paper, a compact lens-assisted quasi-optical THz transmitter, using a 2×2 mm
²
planar log-periodic toothed antenna / bow-tie antenna (LPTA/BTA) integrated InP-based waveguide triple transit region (TTR) photodiode chip and an extended highly-resistive silicon (HR-Si) quasi-optical lens, is developed and presented for directive THz beam forming. In order to decrease the optical propagation loss in the passive optical waveguide section (<;1 dB), as well as enable the THz range capability of the integrated TTR-photodiode by optimized impedance matching to the antenna feed and increase the THz beam directivity (>25 dBi) of the developed LPTA/BTA-integrated THz photomixer, different numerical analyses are carried out with respect to the optical waveguide and the RF antenna characteristics, considering the integrated HR-Si quasi-optics. Experimentally, THz operation up to a frequency of about 300 GHz is demonstrated for the fabricated lens-assisted quasi-optical THz transmitters.