Single Plasmonic Structure Enhanced Dual-band Room Temperature Infrared Photodetection

High Order Magnetic and Electric Resonant Modes of Split Ring Resonator Metasurface Arrays for Strong Enhancement of Mid-Infrared Photodetection

Integration of photonic nanostructures with optoelectrical semiconductors offers great potential of developing high sensitivity and multifunctional photodetectors enabled by enhanced light-matter interactions. Split ring resonator (SRR) array which resonates at different resonant modes, including fundamental magnetic mode (m₀), high order magnetic mode (m₁), and electric (e) mode has been investigated because of the high potential for different applications. In this work, we study photodetection enhancement of these resonant modes of U-shape SRR arrays in the mid-infrared (2-5 μm) range and report, for the first time, the strong enhancement of photodetection by superimposition of m₁ and e modes in an integrated photodetector consisting of a U-shape SRR array and an InAsSb-based heterojunction photodiode. We observe that the m₁ mode in the SRR array shows the strongest enhancement of photocurrent, sequentially followed by the e and m₀ modes. Using superimposed m₁ and e modes, about an order of enhancement in room temperature detectivity (to about 2.0 × 10¹⁰ Jones) is achieved under zero-power-supply without sacrificing the response speed. In addition, polarization-resolved photoresponse between m₁ and e modes and tunable enhancement of photoresponse are also demonstrated. The remarkable enhancement makes mid-infrared photodetection possible to operate at room temperature.

Rotated fourfold U-shape metasurface for polarization-insensitive strong enhancement of mid-infrared photodetection

Metasurface with thin planar resonant elements offers great capability in manipulating electromagnetic waves and their interaction with semiconductors. Split-ring resonator (SRR), as the basic building block, has been extensively investigated for myriad applications owing to its multiple electric and magnetic resonant modes. In this work, we report a rotated fourfold U-shape SRR metasurface for polarization-insensitive strong enhancement of mid-infrared photodetection. The integrated photodetector consists of a rotated fourfold SRR array and an InAsSb based heterojunction photodiode. A photosensitivity enhancement factor as high as 11 has been achieved by adoption of superimposed high order magnetic and electric resonant modes in the SRR metasurface. This work provides a promising pathway for exploring high performance polarization-insensitive photodetection in different electromagnetic wave ranges.