Photonic THz Wireless Communications: Beyond Faster and Farther Link Demonstrations

Photonic THz wireless communications have developed primarily through point-to-point demonstrations aimed at achieving higher data rates and longer transmission distances. In this development, uni-traveling-carrier photodiodes (UTC-PDs) have played a central role by enabling optical heterodyne generation of widely tunable and modulation-transparent THz carriers. This review revisits the progress of UTC-PD-enabled photonic THz wireless links from a faster-and-farther perspective. Specifically, we first examine how representative demonstrations have pushed the performance frontier and then identify the technical factors underlying this progress, with emphasis on low-noise optical source engineering, multiplexing, and equalization-based reception. We further discuss how the same capacity-driven trend has begun to reshape the field beyond fixed point-to-point links, giving rise to laser-enabled functional expansion and array-based beam manipulation. In this context, photonic THz transmitters are increasingly viewed not only as sources of spectrally pure carriers but also as platforms for arbitrary waveform generation and spatial beam control. Taken together, recent progress in photonic THz wireless communications is less a sequence of record updates than a shift from record-oriented links toward function-oriented transmitter architectures.