Long wavelength infrared imaging under ambient thermal radiation via an all-silicon metalens

Abstract

Further miniaturization of imaging systems is prevented by the prevalent, traditional bulky refractive optics today. Meta-optics have recently generated great interest in the visible wavelength as a replacement for refractive optics thanks to their low weight, small size, and amenability to high-throughput semiconductor manufacturing. Here, we extend these meta-optics to the long-wave infrared (LWIR) regime and demonstrate imaging with a 2 cm aperture f/1 all-silicon metalens under ambient thermal emission. We showed that even with the strongly chromatic nature of the metalenses, we can perform ambient light imaging, primarily due to the lack of wavelength discrimination in the sensor, as is the norm for an RGB-camera in the visible.

Full‐Color Metaoptical Imaging in Visible Light

“…Unfortunately, in most works, lasers or light-emitting diodes, including organic light emitting diode (OLED) displays, were used in a controlled lab environment, often used in conjunction with an optical relay. In near-and long-wave-infrared wavelength range, some works did perform imaging using just a single metaoptic, [43,59,60] but they used a filter to limit the wavelength range of the incident light. Similar filtered imaging methods using metaoptic integrated cameras have been reported recently for green light.…”

Wide field-of-view metalens array for the long-wavelength infrared

“…Long-wavelength infrared (LWIR) imaging is a key technology for security surveillance, medical imaging, and non-contact thermal imaging [4,6]. Now, many infrared imaging applications have strict requirements on the size, weight and power of the system, such as intelligent wearable devices and UAV infrared thermography, so it is very important to find a lightweight infrared imaging design scheme [5,7]. However, the traditional dielectric lens processing techniques determine the lenses with bulky volume and curved surface, so that most of current imaging systems are an assemblage of discrete bulk optical components rather than a set of seamlessly integrated components, making it difficult to miniaturize infrared optics devices [1,2,4].…”

“…In 2018, Nanfang Yu et al at Columbia University realized a near-infrared metalens in the 1200-1650 nm band with focusing efficiency ~ 50% [3,9]. In 2021, Arka Majumdar's team achieved a 10 μm wavelength infrared metalens with NA ~ 0.45 using hyperbolic phase at the Washington University [7]. Current research work on metalens has focused on broadband visible and near-infrared wavelengths with multiple discrete wavelengths, and less research has been done on long-wave infrared metalens for wide-angle imaging [11].…”

Design of an all-silicon long-wave infrared meta spiral zone plate

“…Many infrared metasurfaces have been demonstrated which realize focusing at single wavelength [4][5][6][7], real-time polarization imaging [8], achromatic focusing [9][10] and dispersion modulation [11] in the long-wave infrared band. In our previous work, we have demonstrated a simulation method for large-aperture infrared all-silicon metalens and subdiffraction focusing based on meta spiral zone plate in the visible band [12][13].…”