Readout signals calculated for near-field optical pickups with land and groove recording

Optical disk readout signals with a solid immersion lens (SIL) and the land -groove recording technique are calculated by use of a simplified vector-di ffraction theory. In this method the full vector-diffraction theory is appl ied to calculate the diffracted light from the initial state of the disk, a nd the light scattered from the recorded marks is regarded as a perturbatio n. Using this method, we confirmed that the land-groove recording technique is effective as a means of cross-talk reduction even when the numerical ap erture is more than 1. However, the top surface of the disk under the SIL m ust be flat, or the readout signal from marks recorded on a groove decays w hen the optical depth of the groove is greater than lambda/8. (C) 2000 Opti cal Society of America OCIS codes: 210.0210, 210.4590, 050.0050, 050.1950, 050.1960, 070.2580.