Broadband thermal imaging using meta-optics

Subwavelength diffractive optics known as meta-optics have demonstrated the potential to significantly miniaturize imaging systems. However, despite impressive demonstrations, most meta-optical imaging systems suffer from strong chromatic aberrations, limiting their utilities. Here, we employ inverse-design to create broadband meta-optics operating in the long-wave infrared (LWIR) regime (8–12 µm). Via a deep-learning assisted multi-scale differentiable framework that links meta-atoms to the phase, we maximize the wavelength-averaged volume under the modulation transfer function (MTF) surface of the meta-optics. Our design framework merges local phase-engineering via meta-atoms and global engineering of the scatterer within a single pipeline. We corroborate our design by fabricating and experimentally characterizing all-silicon LWIR meta-optics. Our engineered meta-optic is complemented by a simple computational backend that dramatically improves the quality of the captured image. We experimentally demonstrate a six-fold improvement of the wavelength-averaged Strehl ratio over the traditional hyperboloid meta-lens for broadband imaging.

Luocheng Huang, Zheyi Han, Anna Wirth-Singh, Vishwanath Saragadam, Saswata Mukherjee, Johannes E. Fröch, Quentin A. A. Tanguy, Joshua Rollag, Ricky Gibson, Joshua R. Hendrickson, Philip W. C. Hon, Orrin Kigner, Zachary Coppens, Karl F. Böhringer, Ashok Veeraraghavan, Arka Majumdar