Bit-Wise Volumetric Optical Memory Utilizing Two-Photon Absorption in Aluminum Oxide Medium

Aluminum oxide single crystal medium for volumetric optical memory utilizing two-photon absorption is investigated. Static and dynamic testers used to demonstrate bit-wise recording and confocal fluorescent readout. Recording is performed with blue 405 nm laser diodes. Less than 1 nJ of energy per recorded bit was found to be sufficient for data writing. “Negative” readout mode using blue 440 nm laser diode and green 520 nm fluorescence is demonstrated. “Positive” readout mode of operation using red 635 nm excitation laser light and 750 nm fluorescence shows high SNR and prolonged nonvolatile readout. Preliminary data using a dynamic spin-stand tester are presented as well.