A Sub-Terahertz High-Speed Traveling-Wave Switch Modulator Based on Dynamically Tunable Double-Resonant Coupling Units

Abstract

High-speed direct modulation devices are of great significance for the development of high-speed communication systems with large bandwidth, miniaturization, and low complexity. However, an increase in the carrier frequency in the sub-terahertz band and above will negatively impact high-performance direct modulation devices due to the large insertion loss and low on–off ratio. Based on the traveling-wave modulation mechanism, this article adopts the zero-phase-difference amplitude modulator design method. More specifically, a 1- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m small anode Schottky diode is combined with a Z-type matching structure to form a dual-resonant coupling dynamic tunable unit. Interunit coupling is found to further improve the on–off ratio. In this way, high-speed dynamic modulation is performed for the transmission traveling-wave amplitude with low insertion loss and a high on–off ratio. On this basis, a 0.14-THz on–off keying (OOK) high-speed traveling-wave modulator is proposed, and our results showed that a on–off ratio of 25.4 dB could be achieved at the zero-phase-difference point by only using two dynamic structural units. Meanwhile, the control voltage could be adjusted to achieve high-speed modulation with a phase difference of only 3.66 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^\circ$</tex-math> </inline-formula> during the entire control voltage transition, a data rate of 24 Gb/s, and 33.99% sidebands occupation.