| 摘要 |
Disclosed are methods and apparatus for at least one of authenticating, sorting or counting documents, as well as security structures (12) contained within documents and documents (10) containing security structures. A security device or structure (12) includes an optical gain medium and a structure having boundaries that impart an overall geometry to the structure that, in combination with at least one material property of the structure, supports an enhancement of electromagnetic radiation emitted from the gain medium for favoring, in one embodiment, the creation of at least one mode that enhances an emission of electromagnetic radiation within a narrow band of wavelengths. Suitable shapes for the structure (12) comprise elongated, generally cylindrical shapes such as filaments (12B), a sphere shape, a partial-sphere shape, a toroidal shape, a cubical or other polyhedral shape, and a disk shape (12A). The structure (12) preferably comprises at least one of a monolithic structure or a multi-layered structure (12C) or an ordered structure that may provide for distributed feedback. The security device (12) may be incorporated in currency, a passport, a lottery ticket, a negotiable security, a credit or debit card, or any substrate for which it is desired to authenticate, count, encode, sort, or verify.
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