Effect of annular aperture on solid immersion lens-based near-field recording

We analyzed the effect of an annular aperture on solid immersion lens (SIL)-based near-field recording (NFR) to verify the feasibility of applying an aperture to SIL-based NFR. SIL-based NFR with an annular aperture, which blocks the propagating waves, shows good characteristics such as a beam profile on the recording layer and beam propagation inside a medium. By introducing the annular aperture, the focused beam spot size and its sensitivity to the gap between SIL and the surface of the medium can be decreased, and the axial confined beam distribution can be obtained inside the medium. We also show that the general gap control method can be applied to SIL-based NFR with an annular aperture through the calculated exit pupil intensity distribution of the reflected electric field.