Xiang Meng,Jiajun Ma,Kang Xie,Liang Hong,Junxi Zhang,Zhijia Hu
We have demonstrated a low threshold and tunable flexible random laser (RL) in dye-doped poly ethylene glycol diacrylate (PEG-DA) hydrogel, which was prepared by crosslinking polymerization using PEG-DA monomer and photoinitiator. The random lasering is attributed to the light scattering from the porous structure of hydrogels, and the wavelength of random lasing can be tuned by ~3.2 nm in the temperature range from 30 °C to 70 °C. Under the continuous increasing and decreasing temperature cycle, the random lasing tunable phenomenon can still be observed, which proves that this flexible material can be used as a new temperature sensor . In addition, we also explored the application of flexible laser in phototherapy. Considering the good elasticity and transparency of hydrogels, this thermo-responsive property will be of great significance to the biomedical applications of flexible material.
Guangyin Qu,Xiaojuan Zhang,Siqi Li,Yan Kuai,Feng Xu,Liang Lu,Yu Liu,Zhigang Cao,Benli Yu,Anderson S. L. Gomes,Zhijia Hu
In contrast to conventional anti-counterfeiting technologies, which are susceptible to decryption and exhibit limited effectiveness, the utilization of light to dynamically configure soft materials in a fully reversible and programmable manner not only enhances data security but also improves anti-counterfeiting performance. However, achieving precise control over reflection structural colors and laser wavelengths within a broad dynamic range remains a challenge. In this study, a UV-responsive soft helical superstructure is established by combining a photochromic compound with chiral liquid crystals (LCs). By manipulating the Bragg reflection angle, structural reflection colors ranging from red to cyan are successfully achieved. The introduction of an anti-counterfeiting technique that embeds diverse micro-structures provides features such as color adjustability, erasability, and angle-dependent stability. Using the unique properties of this soft helical superstructure, the implementation of a wavelength-tunable LC bandgap laser through optically reconfigurable Förster resonance energy transfer processes is showcased. Furthermore, a straightforward prototype information encoder is developed to mimic the processes of information encoding and decoding, bypassing the need for complex algorithm design. This research underscores the practicality of LC helical soft systems, emphasizing their distinctive responsiveness to light and their applicability in optical programming photonics.
Obtaining whispering gallery mode (WGM) lasing with prominent stability and high quality optical cavities is extremely desirable but still a great challenge. Despite the recent surge of reports on microspheres, nanowires and nanoplatelets metal halide crystals, there has few reports on the morphology of Hemispheres (HSs) in the form of uniform, component-tunable microcrystals. Here, CsPbX 3 (X = Cl/Br) HSs with smooth surface and regular geometry structure were synthesized on silicon substrates by chemical vapor deposition (CVD) method, and the wavelength of laser can be continuously tuned from blue to green (450–540 nm) at room temperature by varying the halide composition. WGM laser with polarization ratio of 0.70 and cavity quality factor Q of 2485 were realized in the CsPbBr 3 HS cavity. Besides, the crystal cavity suggested a high photonic and thermal stability for the superb capability of continuous stable lasing output under ambient conditions. All these results illustrate that the synthesis of cesium lead halide perovskite HSs may provide an alternative solution for fundamental researches and applications in optical devices.
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