Recently, the research group led by Associate Prof. Guanhai Li, Profs. Xiaoshuang Chen and Wei Lu from Shanghai Institute of Technical Physics of the Chinese Academy of Sciences cooperates with the group of Prof. Andrey E. Miroshnichenko from University of New South Wales in Australia on effectively engineering of the polarization, phase and dispersion of mid-wave infrared photons with metasurfaces. They demonstrate a high performance multifunctional meta-photonic device with the capability of polarization-dispersion modulation for mid-wave infrared polarization detection (shown in Figure 1). Relevant research under the title of “Mid-Infrared Polarization-Controlled Broadband Achromatic Metadevice” has been published online in the authoritative journal Science Advances, doi.org/10.1126/sciadv.abc0711.

Polarization detection is based on traditional intensity imaging through adding polarization information to effectively suppress the cluttered background signals and achieve accurate identification of targets and camouflage objects. However, the information must be modulated by a series of specific polarization optical elements before it can be collected and sorted by the detection system. Traditional mid-infrared polarization optical system uses cascaded and discrete polarizers, prisms and lens to perform chromatic aberration correction and polarization modulation. Therefore, it imposes a severe restriction on the broadband polarization photoelectric integrated detection, especially in Aerospace which is very sensitive to volume and weight. Therefore, developing the miniaturized and integratable optical devices with broadband polarization and dispersion manipulations in infrared becomes more urgent.

The metasurface, featuring with a lighter, thinner and more compact planar configuration, can selectively and independently manipulate photons in multiple dimensions at the sub-wavelength scale, which offers us an opportunity to develop the high performance mid-wavelength infrared metadevices. Current metaoptics research mainly focuses on the visible and near-infrared regime. Based on all-silicon platform which is compatible with silicon-based semiconductor processes, the researchers here propose a multifunctional metadevice that can be utilized for photodetector integration in the mid-wavelength infrared. As shown in Figure. 1A, within a continuous bandwidth, photons with different polarization states carry different orbital angular momentum information after being modulated by the metadevice, and can be collected on the predefined focal plane. In addition, by introducing off-axis phase factors into the modulated polarization-phase dispersion spectra of the metadevice, dispersionless directional bunching control of the broadband incidence can be achieved. Due to the simultaneous engineering of polarization and dispersion, different polarized photons are also collected and converged at different design areas of the focal plane with high polarization isolation (Figure. 1B). The experiment results reveal that the focal spots have nearly diffraction-limit sizes and high polarization extinction ratios (Figure. 1C, D). The findings are expected to have applications in the fields of polarization imaging, free space quantum communication, machine vision, and information encryption.

Associate Prof. Guanhai Li, Prof. Xiaoshuang Chen and Prof. Andrey E. Miroshnichenko are the co-corresponding authors. PhD candidates Kai Ou and Feilong Yu are the co-first authors. The research is supported by the Key Research and Development Program of the Ministry of Science and Technology, the National Natural Science Foundation of China, the Shanghai Science and Technology Commission, the Youth Innovation Promotion Association of the Chinese Academy of Sciences, and the Innovation Program of the Shanghai Institute of Technical Physics.