Generation of two-color near-field lights at a nano-slit for high spatial resolution detection of atoms with two-step photoionization

We have proposed a method of detecting neutral atoms with a high spatial resolution exceeding 100 nm. In our scheme, two-color near-field lights generated at a narrow slit with a width of less than 100 nm are used for two-step photoionization of atoms in the ground state. This time, we examined how the generation of near-field light at the nano-slit depends on the incident direction and polarization of excitation light beams by means of the scanning near-field optical microscope (SNOM).