摘要： Surface plasmon waves and Rayleigh anomaly are characteristic optical phenomena exhibited by periodic subwavelength grating structures. In this paper, a hybrid metal-dielectric metasurface is proposed to improve the photoresponse of Ge/Si quantum dot infrared photodetectors (QDIPs) with the limited absorption layer thickness. The composite metasurface consists of a regular array of silicon pillars. The pillars protrude through subwavelength holes in a perforated gold ?lm on detector top. We demonstrate that by combining e?ects of dielectric and plasmonic metal components, the QDIP photoresponse can be signi?cantly improved compared to case when all-dielectric and metal gratings work alone. We observe about 4 times photoresponse enhancement with the hybrid metasurface device relative to a common plasmonic design with the two-dimensional metal hole array. Compared with a bare QDIP, the peak responsivity of the hybrid detector at a wavelength of 4.4 μm is increased by a factor of 15. The enhanced sensitivity is supposed to arise from coupling of the surface plasmon resonance and di?ractive e?ect related to the Rayleigh anomaly.