Evanescent coupling in magneto-optical and phase-change disk systems basedon the solid immersion lens

Results of numerical computations pertaining to evanescent wave coupling fo r near-field magneto-optical and phase-change disks based on the concept of the solid immersion lens are presented. We investigated the relation betwe en the coupling efficiency and the width of the air gap in terms of the thr oughput of the recording process and the resolution of the readout signal. The simulations show a drastic decrease with a widening air gap of the coup ling efficiency by means of evanescent waves into the recording medium. In magneto-optical readout, loss of the signal may be attributed to the reduct ion of magneto-optical interaction, the rise of reflectance, and the variat ion of the relative phase between the two components of polarization. In th e phase-change readout the reduced reflectivity contrast between crystallin e and amorphous maths is the cause of signal reduction. (C) 2000 Optical So ciety of America. OCIS codes: 210.0210, 260.6970.