Dual-Band THz Photonic Pulses Enabling Synthetic mm-Scale Range Resolution

In this letter, we propose and experimentally demonstrate an ultrahigh resolution terahertz (THz) range sensing system by digitally synthesizing multiple-band linear frequency-modulated (LFM) pulses. In the experiment, two-band LFM pulses with 20-GHz bandwidth in the THz band are photonically generated based on frequency-to-time mapping, resulting in a synthetic LFM signal with 40-GHz bandwidth operating within the 315-360 GHz. As a benefit, a range resolution as high as 3.9 mm over more than 2 m is successfully achieved in multi-target ranging. The proposed technology not only releases the requirements for instantaneous bandwidth and sampling rate but also breaks the bandwidth limitation of THz receiver in enabling ultrahigh resolution in the THz region.