1.5-Mbit/s direct readout of line-and-space patterns using a scanning near-field optical microscopy probe slider with air-bearing control

We have demonstrated 1.5-Mbit/s signal readout of a 0.25 μm line-and-space (L&S) pattern on a rotating disk by using a scanning near-field optical microscopy (SNOM) probe slider with air-bearing control. The light transmittance of the probe was greatly increased through direct irradiation of a focused light to a pyramidal probe tip. The bit rate of the signal was enhanced by two orders of magnitude compared to that of existing SNOM systems that use a tapered-fiber probe. The signal contrast, signal-to-noise ratio, and carrier-to-noise ratio for the 0.25 μm L&S pattern were 19%, 17 dB, and 37 dB, respectively. The estimated resolution limit of the probe corresponded to a L&S width of ∼ 130 nm.