Broadband Single‐Mode Hybrid Photonic Crystal Waveguides for Terahertz Integration on a Chip

Abstract

Broadband, low-loss, low-dispersion propagation of terahertz pulses in compact waveguide chips is indispensable for terahertz integration. Conventional two-dimensional photonic crystals (PCs) based terahertz waveguides are either all-metallic or all-dielectric, having either high propagation losses due to the Ohmic loss of metal, or a narrow transmission bandwidth restricted by the range of single-mode operation in a frequency range defined by the PC bandgap, respectively. To address this problem, a hybrid (metal/dielectric) terahertz waveguide chip is developed, where the guided mode is completely confined by parallel gold plates and silicon PCs in vertical and lateral directions, respectively. A unique multi-wafer silicon-based fabrication process, including gold-silicon eutectic bonding, micropatterning, and Bosch silicon etching, is employed to achieve the self-supporting hybrid structure. Theoretical and experimental investigations demonstrate that the hybrid waveguide supports a singlemode transmission covering 0.367-0.411 THz (bandwidth of 44 GHz, over twice wider than that of allsilicon PC waveguides) with low loss (below 0.05 dB mm -1 ) and low group velocity dispersion (from -8.4 ps THz -1 mm -1 to -0.8 ps THz -1 mm -1 ). This work enables more compact, wideband terahertz waveguides and auxiliary functional components that are integratable in chips towards ultra-highdensity integrated terahertz devices in particular in the field of wireless communications.Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff))

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“…The schematic of the proposed optically tunable THz modulator is shown in figure 1 trapping for a long time [26][27][28][29]. Here, we consider the two outer rods of the cavity with a radius of rc.…”

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