Nonlocal phase-change metaoptics for reconfigurable nonvolatile image processing
Guoce Yang, Mengyun Wang, June Sang Lee, Nikolaos Farmakidis, Joe Shields, Carlota Ruíz de Galarreta, Stuart Kendall, Jacopo Bertolotti, Andriy Moskalenko, Kairan Huang, Andrea Alù, C. David Wright, Harish Bhaskaran
Abstract
The next generation of smart imaging and vision systems will require compact and tunable optical computing hardware to perform high-speed and low-power image processing. These requirements are driving the development of computing metasurfaces to realize efficient front-end analog optical pre-processors, especially for edge detection capability. Yet, there is still a lack of reconfigurable or programmable schemes, which may drastically enhance the impact of these devices at the system level. Here, we propose and experimentally demonstrate a reconfigurable flat optical image processor using low-loss phase-change nonlocal metasurfaces. The metasurface is configured to realize different transfer functions in spatial frequency space, when transitioning the phase-change material between its amorphous and crystalline phases. This enables edge detection and bright field imaging modes on the same device. The metasurface is compatible with a large numerical aperture of ~0.5, making it suitable for high resolution coherent optical imaging microscopy. The concept of phase-change reconfigurable nonlocal metasurfaces may enable emerging applications of artificial intelligence-assisted imaging and vision devices with switchable multitasking.