Short Note

[OPTICAL REVIEW Vol. 21, No. 5 (2014) 597-598]
© 2014 The Japan Society of Applied Physics

Multilevel Phase and Amplitude Modulation Method for Holographic Memories with Programmable Phase Modulator

Satoshi HONMA* and Toru SEKIGUCHI

University of Yamanashi, Kofu 400-8511, Japan

(Received November 30, 2013; Accepted May 19, 2014)

The utilization of spatial quadrature amplitude modulation (SQAM) signals with amplitude and phase modulation is a simple method used to improve storage capacity in a holographic data storage system. We propose a multilevel phase and amplitude modulation method for holographic memories with a programmable phase modulator (PPM). In this method, holographic page data is recorded by a two-step exposure process for different phase-modulated data. There is no need to adjust the positions of spatial light modulators (SLM) with high accuracy because we use only one spatial modulator. We estimate the quality of 16 SQAM signals produced by our technique.

Key words: holographic memory, full complex amplitude modulation, multiplexed hologram

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