Pixel-level metal blackbody microcavities via hierarchical laser writing

Abstract

Conventional blackbody cavities, known for their near-unity broadband omnidirectional emissivity (absorptivity), are however constrained by their large volume (e.g., >10 4 cm 3 ), imposing crucial restrictions on integration with existing devices. Here, we introduce the concept of metal blackbody microcavities, comprising thousands of microscale periodic pores created on metals, demonstrating excellent emissivity across visible and infrared (IR) ranges (exceeding 0.94 on average from 0.25 to 20 μm). In the long-wavelength IR (8 to 14 μm) region, near-unity emissivity was successfully achieved by 100-μm-deep metal microcavities with ultralow structural aspect ratios, facilitated by laser-textured multiscale surface morphologies that substantially enhance the light-trapping capabilities. Our findings demonstrate that microcavity-based patterns can produce local emissivity, tunable radiative intensity gradients, wide-angle feasibility, and high-temperature resistance, thereby enabling diverse applications in thermal IR displays such as thermal illusion, IR encryption, and grayscale thermal imaging. Notably, these blackbody microcavities are applicable to various metals, presenting considerable potential for use in extreme environments.