MAGNETOOPTICAL DETECTION USING AN OPTICAL-PHASE SHIFTER IN HIGHER TRACK DENSITY LAND GROOVE RECORDING/

We report the results of magneto-optical (MO) detection using an optic al phase shifter in land/groove recording. We found that the MO detect ion method improves not only readout carrier level but also cross-talk characteristics against optical errors. Using this method with a 693- nm wavelength diode laser and a 0.55-NA objective lens, sufficient rea dout margins against optical errors were experimentally obtained at a 3.69-Gbit/in(2) areal density, which yielded a 0.35-mu m bit length an d a 0.5-mu m track pitch. Recording with a track density 1.4 times hig her was achieved by introducing a 640-nm wavelength diode laser, a 0.7 -NA objective lens, and a 0.258-mu m bit length and yielded an areal d ensity of 6.95 Gbit/in(2).