Sub-harmonic injection locking for phase and frequency control of RTD-based THz oscillator

Khaled Arzi, Safumi Suzuki, Andreas Rennings, Daniel Erni, Nils Weimann, Masahiro Asada, Werner Prost
2020 IEEE Transactions on Terahertz Science and Technology  
Phase and frequency control of resonant tunneling diode (RTD) based terahertz oscillators are major challenges in realizing coherent signal sources for arrayed applications, such as spatial power combining, beam steering, or multi-in multi-out systems. In this letter, we demonstrate frequency locking and control of an RTD oscillating at f 0 ∼ 550 GHz, via radiative injection of a weak sinusoidal subharmonic signal at f 0 /2. Precise frequency control, within the locking range of around 2 GHz,
more » ... demonstrated. A peak output power enhancement of 14 dB in the whole locking range, compared to the free running oscillator, is achieved. Furthermore, occurrence of phase locking is identified by the spectral linewidth reduction, quantifiable in the full-width at half-maximum parameter. A signal linewidth of 490 Hz was achieved in locked operation.
doi:10.1109/tthz.2019.2959411 fatcat:rtvlb5l4irat5ewixjk7ilxb2m