Presentation Information
[C-14-10]J-Band Waveguide Mach-Zehnder Interferometer Using Y-Branch Waveguide and Directional Coupler
Kentaro Soeda1, Kazunori Naganuma1, Yoshinori Yamaguchi1, Kuniaki Konishi1, Hiroshi Ito1, Tadao Nagatsuma1, 〇Junji Yumoto1 (1. The University of Tokyo)
Keywords:
WR-3.4 waveguide,Mach-Zehnder interferometer,Drectional Coupler,Y-branch Waveguide
Waveguide Mach-Zehnder interferometers (MZIs) are essential for next-generation terahertz communications. Previously, we evaluated a J-band MZI using a TE20-mode Y-branch waveguide (TE20-YBWG) for splitting and combining. However, using the TE20-YBWG as a combiner caused phase-mismatched components to reflect back toward the input, inducing multiple reflections and spike-like noise. This study resolves this issue by introducing a directional coupler (DirC) at the combining section. By exploiting the complementary characteristics of the DirC, out-of-phase components are routed to an isolated port, preventing back-reflections. The proposed DirC consists of parallel WR-3.4 waveguides with a 0.26-mm gap and six slotted windows, simulated to provide a 3-dB coupling bandwidth of 30 GHz around 260 GHz. The J-band MZI was fabricated via a 3D printer "RECILS" and electroless copper-on-nickel plating. With an arm length difference of 15.2 mm, the MZI demonstrated clear periodic anti-phase interference with a 15-GHz free spectral range. A maximum transmittance of -1.8 dB and an extinction ratio of 16 dB were successfully achieved while eliminating the spike noise.