Crystals have been widely used in the pharmaceutical industry, structural elucidation, and other biomedical fields. Different polymorphs of one compound possess distinct physical and chemical properties. Some polymorphs are more favorable in applications such as drug delivery and structural characterization. However, owing to the complex mechanisms of the crystallization process, controlling the crystallization result is still difficult. In this study, we found that the femtosecond laser could be applied to control the crystallization of sulfathiazole. By introducing femtosecond laser irradiation, the crystal number and proportion of specific polymorphs were promoted. The interaction of the femtosecond laser with the solution was studied by time-resolved optical microscopy at a time scale of 200 fs to 50 μs. It is suggested that laser-induced cavitation bubbles act as nucleation centers in the crystallization process. Applying ultrasound to tune the bubble dynamics also has impact on the crystallization results. The control of the nucleation results was achieved through femtosecond laser-induced bubble generation. These results offer an approach for controlling the crystallization of sulfathiazole and also provide some knowledge on the process of laser-induced nucleation.

Proteins with different micropatterns have various applications in biosensing, structural analysis, and other biomedical fields. However, processing of micropatterns on single protein crystals remains a challenge due to the fragility of protein molecules. In this work, we studied femtosecond laser processing on single hen egg white lysozyme protein crystals. Optimized laser parameters were found to achieve micropatterning without cracking of protein crystals. The ablation morphology dependence on the laser fluence and the pulse number was discussed to control the processing results. Under a laser fluence higher than 1 J/cm2, the ablation hole was formed. While multipulses with fluence lower than the ablation threshold were applied, the foaming area was observed due to the denaturation of protein. The numerical simulation shows that the ablation results were influenced by the ionization and energy deposition process. Micropatterns including lines, areas, and microarrays can be processed with a minimum size of 2 μm. Processed patterns on the crystal surface can be used for biosensing microarrays and the enhancement of crystal growth. The microprocessing method proposed in this study has potential applications in different fields including biodevices and biomedicine.

Hybrid supercapacitors use electric double‐layer capacitance and Faradaic pseudocapacitance as energy storage mechanisms. This type of supercapacitor is becoming a prime candidate for next‐generation energy storage devices, with advantages in terms of energy density, specific capacitance, and life cycle. However, reducing the electrode area and increasing the specific capacitance of hybrid supercapacitors remain challenging. In this study, a MoCl5 Precursor‐assisted Ultrafast Laser Carbonization (MPAULC) method to fabricate symmetric hybrid supercapacitors with improved capacitance and reduced size is proposed. The method uses an ultrafast laser to induce the formation of carbon/MoO3 composite with the assistance of the MoCl5 precursor. This ultrafast laser carbonization method exhibited high processing precision. The role of the precursor in laser processing is studied using time‐resolved imaging and temperature calculations. The specific area capacitance of the C/MoO3 hybrid supercapacitor is 11.85 mF cm−2, 9.2 times higher than that of the laser‐induced carbon supercapacitor without precursor. The MPAULC method provides a reliable pathway for fabricating miniaturized hybrid supercapacitors with carbon/metal oxide composite electrodes on polymer substrates.

Photonic crystals are utilized in many noteworthy applications like optical communications, light flow control, and quantum optics. Photonic crystal with nanoscale structure is important for the manipulation of light propagation in visible and near-infrared range. Herein, we propose a novel multi beam lithography method to fabricate photonic crystal with nanoscale structure without cracking. Using multi-beam ultrafast laser processing and etching, parallel channels with subwavelength gap are obtained in yttrium aluminum garnet crystal. Combining optical simulation based on Debye diffraction, we experimentally show the gap width of parallel channels can be controlled at nanoscale by changing phase holograms. With the superimposed phase hologram designing, functional structures of complicated channel arrays distribution can be created in crystal. Optical gratings of different periods are fabricated, which can diffract incident light in particular ways. This approach can efficiently manufacture nanostructures with controllable gap, and offer an alternative to the fabrication of complex photonic crystal for integrated photonics applications.

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