Frequency expanded non-interferometric phase retrieval for holographic data storage.

A novel frequency expanded non-interferometric phase retrieval method for holographic data storage is proposed. The limitation of twice Nyquist frequency for phase retrieval with high fidelity is broken through. Only 1 times Nyquist size frequency of the hologram is recorded, reconstructed and detected in our method which is the smallest range for complex multi-level phase retrieval in the current holographic data storage report. Required high-order frequencies for quick phase retrieval are generated artificially by expanding 1 times Nyquist frequency to high-order frequencies with utilizations of frequency periodicity. Therefore, our proposed method can increase storage density due to reducing the recording consumption of media and decreasing the recording area by 4 times compared with twice Nyquist frequency recording.