Figure 1: Working mechanism of the reconfigurable plasmofluidic lens.

(a) Schematic of the reconfigurable plasmofluidic lens, wherein a laser-induced surface bubble is used to control the propagation of SPPs at the metal surface. (b) Schematic of the experimental setup. HWP, half wave plate; M, mirror; CL, cylindrical lens; S, sample; O, oil immersion objective; BS, beam splitter; F, long pass filter; SF, spatial filter; and L, lens. The SPP field is imaged by leakage radiation microscopy, which consists of a high-numerical-aperture oil immersion objective (NA=1.49), three lenses (L1, L2 and L3), and a charge-coupled device camera (CCD). A diode laser with a wavelength of 405 nm is coupled into the leakage radiation microscopy by a beam splitter and focused on the gold surface through the same oil immersion objective. (c–e) Surface bubbles with different diameters (18, 14 and 6 μm, respectively) generated on the gold film. The white dashed circle represents the surface bubble boundary on gold film. Scale bar, 10 μm.