Photonic THz InISAR for 3D Positioning With High Resolution

Terahertz (THz) radar has been considered as a new solution to the dilemmas in performing ultra-high-resolution imaging and obtaining highly precise target information. In this work, a photonic THz interference inverse synthetic aperture radar (THz InISAR) scheme is proposed and proof-of-concept experimentally demonstrated, targeting high resolution positioning of multiple targets. We employ an optical frequency comb and a uni-traveling carrier photodiode (UTC-PD) to photonically generate a linear frequency-modulation (LFM) signal at 290--310 GHz. By using the anti-electromagnetic-interference THz photonic signal source, broadband THz transceivers and efficient InISAR algorithms, 3D positioning of corner reflectors over a distance of 2.2 m at the 300 GHz band is successfully achieved, reaching a resolution of 8 mm for both range and azimuth dimensions, and a maximum height error of 0.4 mm in a height range of 11 cm. To the best of our knowledge, our proposed system represents the ever-first accurate 3D positioning at the THz band above 300 GHz, revealing the great potential applications of THz radar systems.