Storage of multiple holograms of equal diffraction efficiency in a phase-code multiplexing system.

Area of Science:

• Holographic data storage
• Optical information processing
• Materials science (BaTiO3 crystals)

Background:

• Phase-code multiplexing is a technique for increasing storage capacity in holographic systems.
• Optimizing exposure schedules is crucial for achieving high diffraction efficiency and signal-to-noise ratio.
• Existing schedules, often derived for angle-multiplexing, may not be optimal for phase-code multiplexing.

Purpose of the Study:

• To numerically determine optimal exposure schedules for 8-, 32-, and 128-bit phase-code multiplexing systems.
• To develop an analytic prediction for these exposure schedules.
• To experimentally validate the derived schedules and compare them with conventional methods.

Main Methods:

• Computer simulations were performed for 8-, 32-, and 128-bit phase-code multiplexing systems.
• Exposure schedules were numerically obtained to achieve equal diffraction efficiency.
• An analytic double exponential function was derived to predict the exposure schedule.
• Holograms were experimentally recorded in a BaTiO3 crystal using both the derived and conventional schedules.

Main Results:

• The derived analytic prediction achieved a diffraction efficiency variation of less than +/- 13.5% across the systems.
• Experimental recordings showed good agreement between the computer simulations and the derived exposure schedule.
• The new schedule outperformed conventional schedules derived for angle-multiplexing in BaTiO3 crystals.

Conclusions:

• The developed double exponential function provides an accurate and applicable analytic prediction for phase-code multiplexing exposure schedules.
• The validated numerical approach and derived schedule significantly improve holographic data storage performance.
• This work offers a more efficient method for optimizing holographic storage systems.