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Bioinspired superhydrophobic surfaces are an artificial functional surface that mainly extracts morphological designs from natural organisms. In both laboratory research and industry, there is a need to develop ways of giving large-area surfaces water repellence. Currently, surface modification methods are subject to many challenging requirements such as a need for chemical-free treatment or high surface roughness. Laser micro-nanofabrications are a potential way of addressing these challenges, as they involve non-contact processing and outstanding patterning ability. This review briefly discusses multiple laser patterning methods, which could be used for surface structuring toward creating superhydrophobic surfaces.

Periodical structures induced by pulsed lasers are a unique phenomenon when pulsed lasers irradiate on some material surfaces. These periodical structures with a subwavelength-scale period hold potential in integrated-optics and biomimetic micro-nanodevices for their direct shaping by laser pulses. However, the blurred nature of the laser-induced structuring hinders its further exploration in these application scopes. In this review, the plasmon-mediated structuring targeted on various materials, both organic and inorganic, will be discussed profoundly.

Optical microcavities have been widely employed for sensing and detection, because of their ultrasensitive responsiveness to surrounding environment. Here we report an active disk-shaped whispering gallery mode (WGM) microcavity fabricated from a water-sensitive material of dye-doped PEG-DA hydrogel through two-photon polymerization. We demonstrate that as the environment humidity changes the microcavity can homogenously expand or shrink to keep the disk-shaped structure, producing stable WGM lasing emissions. We further show that the WGM wavelength of the microlaser shifts linearly as the humidity increases from 25% to 65%, resulting in a wavelength variation of about 1.72 nm, which indicates that the stretchable microlaser can be acted as a humidity sensor. Due to the “smart” response of humidity and biocompatibility of PEG-DA hydrogel material, our results provide a way to the design and fabrication of flexible PEG-DA hydrogel biochips for biomedical applications.

Optical microcavity is widely used in high precision sensing and detection fields because of its sensitivity to the environment. Herein, we used femtosecond laser direct writing (FsLDW) to apply PEG-DA hydrogel (polyethylene glycol diacrylate), a polymer material with rapid and significant response to environmental humidity, in fabrication of a whispering gallery mode (WGM) microcavity resonator. Changes in ambient humidity made the cavity expand or contract evenly with stable WGM laser emission. In our experiment, two microcavities spaced 1 μ m apart with a radius of 10 μ m were prepared. Since the volume of the microcavity can be controlled by changing the ambient humidity, the coupling of photonic-molecular microcavities can be intelligently controlled by changing the environmental humidity. The results will inspire further novel ideas about controllable photonic-molecular microcavities.