Optical data storage tries to cope with the strong need for exchangeable super high-density, high-data rate storage memories that can be easily copied and can be produced at low cost. In this search for higher
information density, different approaches are being investigated to make read-out of smaller marks possible. In this paper we propose a method to improve the optical resolution, without making the spot size on the disk smaller than the wavelength. The idea is to reconstruct the bit pattern from the complete field profile (including amplitude and phase) of the light response reflected on the disk. Phase and amplitude information are measured by picking up the wave front into different modes of a multimodal waveguide. Once picked up, these modes can be split up by a photonic integrated circuit to be measured by different detectors. By combining the information from these different responses the bit error rate can be improved substantially.
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