High order magnetic and electric resonant modes of split ring resonator metasurface array 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 ...