Hybrid lead halide perovskites have made great strides in next-generation photovoltaic and optoelectronic devices. Random lasers based on perovskite materials have been intensively investigated, but the miniaturization of perovskite random lasers has not been achieved up to now. Here, we report the fabrication of perovskite random lasers based on perovskite films deposited on the optical fiber facets using a dip-coating method. Under optical pumping conditions, random lasing was observed with minimum threshold energy of 32.3 μJ/cm2 at ~550 nm; also, the lasing threshold decreased with increasing diameter of the optical fiber. The results show that the random lasing emission originates from the scattering between the perovskite crystal grains, and the decreased threshold is attributed to the increased active area of the perovskite film. The directionality of perovskite random lasers indicates that the divergence angle of the laser beam is less than 60°. We also demonstrate that the perovskite random laser on the fiber facet can prevent speckle formation and improve image quality. These results may promote the applications of random lasers in compact sources and integrated optoelectronic devices.

Single-mode plasmonic lasing has great potential for use in photonic and sensing applications. In this work, single-mode lasing is realized using a plasmonic-enhanced woven microfiber that shows ultrahigh sensitivity to the ambient environment. This plasmonic-enhanced microfiber is fabricated by spraying Ag nanospheres onto rhodamine 6G-doped polymer microfibers. Single-mode laser emission with an ultranarrow linewidth (0.1 nm) and a low threshold (18.8 kW/ mm 2 ) is achieved in the microfiber using the effects of mode selection and plasmonic enhancement provided by the Ag nanospheres. A large wavelength shift in the singlemode lasing is observed when the proposed laser is used as a sensor and exposed to a humid or acidic environment. The wavelength shift is attributed to refractive index variations in the microfiber caused by either moisture absorption or chemical reactions. In humidity sensing, the laser's sensitivity is as high as 826.6 pm/% relative humidity (RH) and the detection limit is 0.051% RH. An innovative strategy for acetic acid gas sensing is proposed that uses the chemical reaction with rhodamine 6G, and its minimum response time is 5 min. Because of the microfiber's excellent fabric compatibility, a wearable sensor is fabricated by weaving the plasmonic-enhanced microfiber into clothes, and this sensor demonstrates extreme bending stability. The results reported here provide a novel approach to the design and fabrication of ultrasensitive wearable sensors for multifunctional sensing applications.

Engineering practices indicate that narrow braced excavation exhibits a clear size effect. However, the slip circle method in the design codes fails to consider the effect of excavation width on basal heave stability, causing waste for narrow excavation. In this paper, numerical simulation for basal heave failure of excavation with different widths was performed by FEM with SSRT (shear strength reduction technique). The results revealed that the failure mechanism of narrow excavation is different from the complete slip circle mode. In addition, the safety factor decreases increasingly slowly as the excavation widens and stabilizes when approaching the critical width. Subsequently, the corresponding computation model was presented, and an improved SCM (slip circle method) was further developed. Finally, the engineering case illustrated that it can effectively optimize the design, which exhibits clear superiority.

Perovskite solar cells (PSCs) have received tremendous attention because of their advantages of low fabrication cost and rising power conversion efficiency (PCE). However, the poor crystalline quality of perovskite materials...