Figure 6: FDTD simulation results.

(a) SPP field launched by an arc grating without a bubble. (b,c) SPP fields after passing through two surface bubbles with radius of 6 and 5 μm, respectively. The green dashed circle represents the surface bubble boundary on gold film. The white dashed line indicates the SPP focal spot when bubble is absent on the gold film. Scale bar, 5 μm.