Design and Applications of Multi-layer Meta-Optics

Abstract

With rapid advancements in computational simulation tools and nanofabrication technology, the light-matter interaction can be explicitly controlled to create metasurfaces. Metasurfaces for optical applications are termed meta-optics, and they are composed of periodic arrays of sub-wavelength scatterers that modulate the phase of light. Numerous studies have leveraged the compact form-factor and sub-wavelength phase control for applications including imaging, beam steering, optical sensing, and optical computing. In particular, compression of multiple optics into a single meta-optical layer for compact, multi-functional imaging systems has been extensively studied. The challenges, limitations, and successes of single-layer meta-optics are well-understood, but extension to multi-layer meta-optics is less explored. This thesis presents developments in design and applications of single- through multi-layer meta-optics. First, we demonstrate singlet meta-optics for single-wavelength and broadband imaging at thermal wavelengths. Then, in a more complex application, we use a single layer of meta-optics to optically perform a convolution operation as part of a hybrid optical-electronic convolutional neural network for image classification. Using this hybrid approach, we estimate a reduction in latency and power consumption by over two orders of magnitude while maintaining 93% classification accuracy on the MNIST dataset. For doublet meta-optics, we demonstrate wide field of view imaging at both thermal and visible wavelengths. In the thermal range, we demonstrate 80 degree full field of view at 10 um wavelength by combining a meta-optic with a 1 cm diameter external aperture. In the visible, we demonstrate a wide field of view (greater than 60 degree) and large aperture (2.1 cm) eyepiece consisting of two layers of meta-optics for augmented/virtual reality and night vision applications. At the design wavelength of 633 nm, the meta-doublet eyepiece achieves comparable performance to a refractive lens-based eyepiece system. Finally, we present a meta-optics triplet for zoom imaging in the mid-wave infrared. By varying the axial distances between the optics, the meta-optic triplet achieves high quality imaging over a zoom range of 5x, with 50 degree full field of view in the widest configuration. These applications demonstrate the potential for meta-optics to replace conventional components in complex optical systems, and in particular we demonstrate the success of multi-layer meta-optics for wide field of view imaging.