Communication using terahertz (∼10¹² Hz) electromagnetic waves is critical for developing sixth-generation wireless network infrastructures. Conflictions between stable radiation and frequency modulation of terahertz sources impede the superposing of transmitting signals on carrier waves. The Josephson junctions included in a cuprate superconductor radiate terahertz waves with frequencies proportional to the bias voltages. Thus, the modulation of the bias voltage leads to the modulation of the Josephson plasma emission (JPE) frequency. This study aims to demonstrate the generation of frequency-modulated (FM) terahertz continuous waves from Josephson junctions. A FM bandwidth of up to 40 GHz was achieved when 3 GHz sinusoidal waves were superimposed on 840–890 GHz carrier waves radiated by a JPE. The results verify that the instantaneous JPE frequency follows the gigahertz-modulated bias voltage. The wide-band FM terahertz generation by a monolithic device shows a sharp contrast to the mode-lock frequency comb constructed using highly sophisticated optics on a bench. A further increase of the modulation amplitude facilitates up- or downconversion of frequencies over more than one octave. The obtained FM bandwidth exhibited an improvement of two orders of magnitude in the demodulation signal-to-noise ratio compared with the amplitude-modulated waves. The demonstrated FM JPE stimulates further research on terahertz communication technology and metrology using superconducting devices.

使用太赫兹（∼ 10 ¹²  Hz）电磁波进行通信对于开发第六代无线网络基础设施至关重要。太赫兹源的稳定辐射和频率调制之间的冲突阻碍了传输信号在载波上的叠加。铜酸盐超导体中包含的约瑟夫森结辐射太赫兹波，其频率与偏置电压成比例。因此，偏置电压的调制导致约瑟夫森等离子体发射（JPE）频率的调制。本研究旨在演示从约瑟夫森结产生调频（FM）太赫兹连续波。当 3 GHz 正弦波叠加在 JPE 辐射的 840-890 GHz 载波上时，可实现高达 40 GHz 的 FM 带宽。结果验证了瞬时 JPE 频率遵循千兆赫兹调制偏置电压。单片器件产生的宽带 FM 太赫兹与在工作台上使用高度复杂的光学器件构建的锁模频率梳形成鲜明对比。调制幅度的进一步增加有利于超过一个倍频程的频率上变频或下变频。与调幅波相比，所获得的调频带宽的解调信噪比提高了两个数量级。所展示的 FM JPE 促进了使用超导器件的太赫兹通信技术和计量学的进一步研究。