Integration and Modeling of a Metasurface Spectropolarimeter for Space Applications

Abstract

Electromagnetic metasurfaces in recent years have drawn significant attention in the Optics community due to their novel optical properties and miniaturized integration advantages. Since the optical properties of those materials are complex to model and require finer theory than what implied in geometrical optics, systematic integration study of those solutions is not reported in Literature and motivates this research. In previous work, the design of polarization-sensitive spectral filters based on metasurfaces devices and integrated into Bragg reflectors has been reported. The use of such a spectropolarimeter concept may lead to significant miniaturization improvements in Space applications, where launches of small satellites are becoming accessible to not-governmental companies and trending. Typical spectral and polarimetric functionalities are currently integrated with several additional components required for the propagation of light. The metasurface based spectropolarimeter concept operates in a division of focal plane and can be integrated on off-the-shelf CMOS sensors, when opportune factors are taken into considerations, with the use of a single lithographic step. The main difficulty in their use arises from the limited bandwidth dictated by the Bragg reflector and the polarization response of the metasurface, as well as strict requirements of telecentricity to limit angle-dependence at the focal plane. In the present work, we offer novel modeling tools to predict the electromagnetic performance of the device in terms of diffraction and spectral response. We explicit how those tools, in comparison with other approaches like Finite Element Methods, can provide an efficient and physical-based assessment for the design of the spectro-polarimetric filters. We apply then such tools to analyze the diffraction of the filters and the integration of the sensor in a Space Mission for aerosol detection in the VIS and SWIR range, by designing a set of filters able to overcome the bandwidth limitations above mentioned, finally providing simple engineering figures in terms of integration requirements to be considered. The work sets the bases for further improvements, on one side, in the modeling of those structures and on the other side in their integration in complex systems.