Additive manufacturing of highly reconfigurable plasmonic circuits for terahertz communications

While in most existing terahertz communications systems, the THz carrier wave is transmitted via free-space channels, the THz waveguide-based integrated solutions can be of great utility at both the transmitter and receiver ends, thus simplifying the miniaturization and mass production of cost-effective THz communications systems. Here we present a new type of modular THz integrated circuits based on the two-wire plasmonic waveguide components fabricated using a combination of stereolithography (SLA) 3D printing, wet chemistry metal deposition, and hot stamping techniques. Particular attention is paid to the design of the optical circuits based on the two-wire waveguides suspended inside a protective micro-sized enclosure. Such waveguides feature low transmission and bending losses, as well as low dispersion. Using such waveguides as basic building blocks, we then demonstrate several key optical subcomponents, such as low loss broadband 2 x 1 THz couplers that use two coalescing two-wire waveguide bends, as well as broadband waveguide Bragg gratings that feature a paper sheet with a periodic sequence of metal strips inserted into the air gap of a two-wire waveguide. Finally, using these developed subcomponents, a two-channel add-drop multiplexer is demonstrated to operate at 140 GHz. We believe that the reported micro-encapsulated two-wire waveguide-based modular platform can have a strong impact on the field of THz signal processing and sensing due to the ease of device fabrication and handling, high degree of reconfigurability, and high potential for real-time tunability. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement