Generation and direct dark-field imaging of photonic jets of single dielectric microspheres under evanescent illumination
摘要
Herein, for the first time, we report the generation and direct dark-field imaging of photonic jets (PJs) of single dielectric microspheres illuminated by evanescent waves generated using narrow and broadband radiation from a supercontinuum source. The evanescent waves are generated on the surface of a prism by creating the total internal reflection of light within it. The images are recorded by varying the radius of the microspheres, ranging from 10 to 18 μm. The experimental images obtained with supercontinuum, blue, green, and red light are compared. The length and width of the PJs are found in the order of micrometers due to the large size of the microspheres. The proposed technique is simple and efficient in visualizing PJs, allowing for the simultaneous estimation of their length and width. It can also allow us to visualize the photonic nanojets, which have dimensions in the order of nanometers, usually generated from single tiny dielectric microspheres under evanescent illumination. For comparison, the theoretical simulations are performed on the PJs generated from single dielectric microspheres under non-evanescent (direct) illumination. Finally, the possible applications of the PJs generated by evanescent waves in different microscopy systems are reported here.