Signal Processing for the MAMMOS Channel (Invited Review Paper)

概要

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In a Magnetic Amplifying Magneto-Optic System (MAMMOS) the InterSymbol Interference (ISI) problem is solved by copying bits from the recording layer to the readout layer through an aperture formed by the lagging thermal profile of the optical spot. The SNR problem is tackled by expanding and-after detection-collapsing of the copied domain with an external magnetic field. The consequence is that the detected MAMMOS peaks are partly in phase with the applied external field and do not contain information about the exact location of the bits in the recording layer. This hampers straightforward clock recovery. A new clock recovery method where the external field is switched depending on the detected data solves this problem. First experiments with a phase-locked loop (PLL) based on this clock recovery method show a jitter of 10.8% when detecting I1 marks separated by <I9>____<_>spaces at linear bit dimensions of 250 nm for a system with a laser spot diameter of 0.66 μm (λ=658 nm ; NA=0.6).
2002-10-01