Flexible broadband metamaterial absorber in long-wave infrared with visible transparency fabricated by laser direct writing.

Absorption of the long-wave infrared from human beings and the surroundings is a key step to infrared imaging and sensing. Here we demonstrate a flexible and transparent broadband infrared absorber using the photoresist-assisted metamaterials fabricated by one-step laser direct writing. The photoresist is patterned by the laser as an insulator layer as well as a mask to build the complementary bilayer metamaterials without lithography. The average absorptivity is 94.5% from 8 to 14 µm in experiment due to the broadband destructive interference of the reflected beam explained by the Fabry-Perot cavity model. The proposed absorber is applicable to various substrates with additional merits of polarization insensitivity and large angle tolerance, which offers a promising solution for thermal detection and management.

Ultrathin, reflective light-field imaging film realized by self-releasing UV-curable nanoimprinting lithography.

Light-field imaging has emerged as a technology allowing the capture of richer visual information from the world. Ultrathin, reflective light-field imaging film is fabricated by using self-releasing ultraviolet (UV)-curable nanoimprinting lithography. The plenoptic function is built to generate the dense reflective light field in a two-dimension plane in which the occlusion perception can be seamlessly incorporated in the recording process. A self-releasing nanoimprinting technique is developed to realize the imaging film with a thickness of 25 µm and a full field of view (FOV). The results pave the way toward developing high-performance light-field imaging device that can be used as a visual security feature or in virtual/augmented reality and computer vision applications, etc.

Floating quick response code based on structural black color with the characteristic of privacy protection.

Since the printing quick response (QR) code can be easily produced and duplicated as a potential tool for cybercriminals, QR code security has been a hotly debated issue across globe. Here we demonstrate a floating QR code device based on the moiré principle which has the advantage of displaying an appealing three-dimensional (3D) effect and privacy protection. In the imaging system, the microlens array (MLA) contributes to efficiently sampling the multiple elemental images and the metal-coated nanostructure yields patterned structural black color with a high pattern resolution (>12, 500 dpi). A virtual mask scheme is specially developed in the elemental image construction, allowing for eliminating the crosstalk between neighboring units and containing more information in one unit without the necessity for ultra-high-resolution fabrication process and sophisticated operation. The proposed QR code device, capable of being read by an unmodified smart phone, is inexpensive, mass-producible, nondestructive, unclonable and convenient for authentication. This new solution should take a place among the existing solutions to fight counterfeiting and QR code attacks.