Spatially, Spectrally Single-Mode and Mechanically Flexible 3D-Printed Terahertz Transmission Waveguides

Emerged terahertz transmission waveguides or fibers will enable novel terahertz systems and applications. High-quality output beam profiles, mechanical flexibility and reliability are among the most crucial and challenging characteristics of terahertz transmission waveguides. Here, we design and fabricate the flexible and stretchable transmission waveguides by 3D printing to guide radiation from terahertz (THz) quantum cascade lasers (QCLs) lasing at the frequency of 2.58 THz. Composite silver nanoparticles and polydimethylsiloxane are coated on the inner surface of the 3D-printed polycarbonate/rubber substrate tube. Output beam profiles from the transmission waveguides, which are captured by a room-temperature terahertz camera, demonstrate single-mode spatial intensity distribution. Transmission spectra are measured out from the waveguides and single-mode characteristics of THz QCLs are preserved from threshold to peak bias. More than 300 times of bending and force-strain curves are tested for the 3D-printed flexible terahertz transmission waveguides, the propagation losses exhibit no obvious change, demonstrating a superior mechanical endurance.