文摘
We propose a new method for selective imaging of surface bound probes or simultaneous imaging of surface bound plus fluorescence from dye molecules in bulk water solution. The principle of this method relies on the use of two optical modes with different mode distributions, field decay lengths, and polarization states that are sustaining in a plasmon waveguide. The two modes with different decay lengths couple to dye molecules of different regions at different distances from the PCW鈥搘ater interface. The emission from two different regions occur as two coupled emission rings with different polarizations and emitting angles in the back focal plane (BFP) images. By using an electric-driven liquid crystal in BFP imaging, we selectively imaged surface or surface plus bulk fluorescence. Accordingly two coupled emissions can be switched ON or OFF independently, which are for either surface or bulk fluorescence imaging. Our work provides a new method for fluorescence imaging or sensing just by using a planar multilayer film, which may be a useful for fluorescence-based techniques in chemistry, materials science, molecular biology, and medicine.