Optical: systems and elements – Holographic system or element – Having particular recording medium
Patent
1997-09-02
1999-11-02
Spyrou, Cassandra
Optical: systems and elements
Holographic system or element
Having particular recording medium
359 7, 430 1, 430 2, 365125, G03H 102, G03H 104, G11C 1304
Patent
active
059781084
ABSTRACT:
Ferroelectric materials are disclosed as reversible holographic recording media (25) for use in two-photon recording systems. The ferroelectric materials disclosed herein provide long-lived electronic states intermediate the ferroelectric material's valence and conduction bands. These intermediate states have a sufficiently long life (on the order of 1 to 100 milliseconds) that low-power continuous wave ("cw") lasers (1) can be used to record interference patterns on them. Thus, two-photon holographic recording systems are also disclosed which do not require high-power, short pulse length, mode-locked or Q-switched lasers. The disclosed two-photon holographic recording systems provide for absorption of a first photon which excites electrons of holographic recording media to an intermediate state. Thereafter, upon absorption of a second photon, the electrons are promoted to the media's conduction band where they are arranged according to the interference pattern provided by the recording system. Importantly, the disclosed holographic recording systems employ visible and near IR cw lasers such as diode lasers.
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Bai Yu Sheng
Kachru Ravinder
Chang Audrey
Spyrou Cassandra
Stanford Research Institute
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