Dynamic read/write characteristics of magneto-optical TbFeCo and DyFeCo disk

Amorphous ternary TbFeCo and DyFeCo alloy films were prepared on PMMA pregrooved disks with a dielectric surface layer by Electron-Beam Evaporation technique. Thermomagnetic recording and readout experiments were carried out on these disks using magneto-optical disk player with a detector of Si-APD. It was found that S/N, proportional to
\sqrt{R}\cdot\Theta_{k}
, is dependent on the thickness of dielectric layer both theoretically and experimentally, where the optimum thickness exists. The mean value of carrier-to-noise ratio (C/N) of 53 dB (resolution bandwidth 30 KHz) was obtained at 2.048 Mb/s (NRZ), which was 5dB larger than that of the disk without a dielectric layer.