Abstract
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.
Highlights
TERAHERTZ (THZ) waves have attracted increasing attentions in the field of biomedical applications due to the characteristics of being non-ionizing, non-invasive and sensitive to moisture in biological tissues [1,2]
Ag NPs form closed and dense structures in PDMS matrix [47] and the composite layer could serve as a reflective layer of the 3D-printed terahertz waveguides
In order to find the optimized number of the composite PDMS and Ag NPs coating layer, the transmission loss of 3D-printed terahertz waveguide was investigated after coating different numbers of layers, as shown in the top scale of Fig. 4(a)
Summary
TERAHERTZ (THZ) waves have attracted increasing attentions in the field of biomedical applications due to the characteristics of being non-ionizing, non-invasive and sensitive to moisture in biological tissues [1,2]. As important and effective methods to guide and deliver THz radiation, terahertz transmission waveguides or fibers have been emerging technologies, which are able to be utilized in THz imaging, sensing and communication [8,9]. PDMS has steady dielectric characteristics, low transmission loss in the THz wavelength [43] and serves as the role of smoothing the inner surface of the substrate tube fabricated by 3D printing [44]. To the best of our knowledge, this is the first time to demonstrate 3Dprinted flexible and stretchable terahertz transmission waveguides Such waveguides fabricated by low-cost and flexibly designed 3D printing technology will play an important role in terahertz sensing, non-destructive inspection and medical diagnosis
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