Design of a plasmonic-organic hybrid slot waveguide integrated with a bowtie-antenna for terahertz wave detection

Abstract

Electromagnetic (EM) wave detection over a large spectrum has recently attracted significant amount of attention. Traditional electronic EM wave sensors use large metallic probes which distort the field to be measured and also have strict limitations on the detectable RF bandwidth. To address these problems, integrated photonic EM wave sensors have been developed to provide high sensitivity and broad bandwidth. Previously we demonstrated a compact, broadband, and sensitive integrated photonic EM wave sensor, consisting of an organic electro-optic (EO) polymer refilled silicon slot photonic crystal waveguide (PCW) modulator integrated with a gold bowtie antenna, to detect the X band of the electromagnetic spectrum. However, due to the relative large RC constant of the silicon PCW, such EM wave sensors can only work up to tens of GHz. In this work, we present a detailed design and discussion of a new generation of EM wave sensors based on EO polymer refilled plasmonic slot waveguides in conjunction with bowtie antennas to cover a wider electromagnetic spectrum from 1 GHz up to 10THz, including the range of microwave, millimeter wave and even terahertz waves. This antennacoupled plasmonic-organic hybrid (POH) structure is designed to provide an ultra-small RC constant, a large overlap between plasmonic mode and RF field, and strong electric field enhancement, as well as negligible field perturbation. A taper is designed to bridge silicon strip waveguide to plasmonic slot waveguide. Simulation results show that our device can have an EM wave sensing ability up to 10 THz. To the best of our knowledge, this is the first POH device for photonic terahertz wave detection.The detection and measurement of electromagnetic fields over a large spectrum have attracted significant amounts of attention in recent years. Traditional electronic electromagnetic field sensors [1, 2] use large active conductive probes which perturb the field to be measured. This also makes the devices bulky with strict limitation on RF bandwidth. In order to address these problems, integrated photonic electromagnetic field sensors [3-6] have been developed, in which an optical signal is modulated by an electric field collected by a miniaturized antenna. In our recent work [7], we have designed, fabricated and experimentally demonstrated a compact, broadband and highly sensitive integrated photonic electromagnetic field sensor to cover the X band of the electromagnetic spectrum (8-12GHz). This photonic electromagnetic field sensor consists of an electro-optic (EO) polymer refilled slot photonic crystal waveguide (PCW) optical modulator coupled with a gold bowtie antenna, as shown in Figs.1 (a) and (b). The frequency was targeted around 10GHz which is the central frequency of X band. However, due to the intrinsic limitation of silicon photonic crystal waveguide based structure with relative large RC time constants, such RF sensors can only go up to tens of GHz. To overcome this limitation, our group first proposed the idea of using EO polymer refilled pl...

Silicon–Organic and Plasmonic–Organic Hybrid Photonics

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Key Roles of Plasmonics in Wireless THz Nanocommunications—A Survey

“…As far as concerns plasmon based THz wave detectors, hybrid plasmonic schemes consisting of plasmonic waveguides along with silicon waveguides, all integrated with conventional nanoantenna structures, such as dipole or bowtie antennas are considered to be promising, beyond state of the art approaches. A POH slot waveguide integrated with a bowtie antenna is proposed in [150], as a THz wave detector. In this structure, a taper is used to connect silicon strip waveguide with the electro-optical polymer refilled plasmonic slot waveguide, all integrated with a bowtie antenna.…”

Gain improvement of THz antenna using semicircular slot and modified ground plane

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