In this paper, the authors review the optical principles underlying the fabrication of 3D periodic nanostructures prepared using holographic lithography (HL) as well as their applications toward chemical sensors and energy storage devices using 3D functional nanomaterials. HL is potentially useful for the simple and rapid fabrication of defect‐free large‐area periodic nanostructures with various structural geometries. The use of optical elements, such as well‐designed prisms and diffraction gratings, improves the reproducibility of the manufacturing process by simplifying complicated optical setups. 3D functional nanostructures, including semiconductor and metallic nanomaterials, are useful in highly sensitive photonic crystals and plasmonic sensors, and high‐performance 3D electrodes for use in energy production and storage devices.

The molecular absorption spectrum in the midinfrared (mid-IR) region is typically measured by Fouriertransform infrared spectroscopy (FTIR). Such spectrometers require complex and delicately aligned interferometers, which increases their size and cost. Here, we present an alternative compact mid-IR spectrometer, which uses a variable mid-IR filter with a gradual change of cavity length between two silicon/air dielectric mirrors. When combined with a modern uncooled thermal imaging camera, hyperspectral filtering can provide a powerful solution for the miniaturization of mid-IR spectrometers. By using the hyperspectral filter, light from a broadband light source can be dispersed and assigned to individual pixels of a microbolometer array of the thermal imaging camera. This technology offers an inexpensive and compact mid-IR spectrometer design with no moving parts and rapid acquisition time.

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