Stretchable Random Lasers with Tunable Coherent Loops

Abstract

Stretchability represents a key feature for the emerging world of realistic applications in areas, including wearable gadgets, health monitors, and robotic skins. Many optical and electronic technologies that can respond to large strain deformations have been developed. Laser plays a very important role in our daily life since it was discovered, which is highly desirable for the development of stretchable devices. Herein, stretchable random lasers with tunable coherent loops are designed, fabricated, and demonstrated. To illustrate our working principle, the stretchable random laser is made possible by transferring unique ZnO nanobrushes on top of polydimethylsiloxane (PDMS) elastomer substrate. Apart from the traditional gain material of ZnO nanorods, ZnO nanobrushes were used as optical gain materials so they can serve as scattering centers and provide the Fabry-Perot cavity to enhance laser action. The stretchable PDMS substrate gives the degree of freedom to mechanically tune the coherent loops of the random laser action by changing the density of ZnO nanobrushes. It is found that the number of laser modes increases with increasing external strain applied on the PDMS substrate due to the enhanced possibility for the formation of coherent loops. The device can be stretched by up to 30% strain and subjected to more than 100 cycles without loss in laser action. The result shows a major advance for the further development of man-made smart stretchable devices.

White light induced photo-thermal switching in a graphene-flake-mixed ZnO nanoparticle random laser

“…For this purpose, several approaches for the control of random lasing modes had been proposed such as use of resonant scatterers [7][8][9][10][11], limiting excitation area [12,13], temperature control [14][15][16], tuning density of scatterers [17]. Among these approaches, it had been reported that changes in lasing modes were observed in random lasers fabricated on a soft substrate due to the structural changes induced by mechanically stretching the substrate [18][19][20], which has a merit of in situ tuning of lasing modes by adjusting the amount of bending or stretching the substrate. However, for maintaining the reproducibility and achieving the precise tuning, it is indispensable to use driving mechanism equipped with the structure, such as actuators.…”

Magnetically Controllable Random Lasers

“…This result provides a strong evidence to support the fact that the density of Fe 3 O 4 NPs can be manipulated by the applied magnetic field. Our previous work also suggests that increasing scatterers density could lead to lasing with a shorter wavelength due to the decreasing cavity length . Besides, the influence of the magnetic field toward the threshold of the MCRLs has also been discussed and provided in Figure S6 in the Supporting Information.…”

“…The tuning strategies of preprocess include modifying the absorption condition, the size of scatterers, and the geometry of photonic crystals . Besides, external parameters such as optics, electricity, temperature, and deformation, can realize wavelength tunability after the fabrication of disordered nanostructures, so called postprocess. Further, people drive persistent endeavors to control the random lasing modes.…”

Compositional and structural engineering of inorganic nanowires toward advanced properties and applications

“…Luminescent nanowires rationally fabricated into diverse shapes exhibit flexible photonic properties with respect to light propagation behavior and waveguide cavities, such as Fabry‐Perot and whispering gallery modes . Numerous semiconductor nanowires, including metal oxides and III‐V and II‐VI compounds with bandgaps ranging from ultraviolet to infrared, have also been considered.…”