US 5,761,111 A · Method and apparatus providing 2-D/3-D optical information storage and retrieval in transparent materials

Abstract

Sub-micron-scale, micron-scale and greater than micron-scale, crack-free and regularly-shaped structures of high-contrast refractive index are provided in transparent storage media by controllably focusing ultrashort laser pulses in the bulk of virtually any transparent medium respectively during operation in a "low energy," a "high energy", and a "third" operating regime. In any operating regime, the crack-free and regularly-shaped structures of high-contrast refractive index may be controllably patterned in 2-D or 3-D so as to permanently store both digital and non-digital information in the bulk of the transparent storage medium. For digital-type information, greater than one (1) Terabit, and up to one hundred (100) Terabit, digital information storage capacity in a CD-ROM sized disc is provided. Virtually any non-digital information may be permanently stored therewithin, such as corporate logos, alphanumeric characters, security codes, and artistic images, or diffraction gratings, diffractive optical elements or other optical structures. Information permanently stored in 2-D or 3-D in the bulk of any transparent medium is read by the unaided eye, and by optical microscopy (scattered and transmitted light modes), phase contrast microscopy, laser DIC microscopy and confocal microscopy in dependance on the type of the information and on the operating regime. Information may be written or read in series or in parallel.

Claims45

Dependent claims

A method providing optical information storage in a transparent material having a bulk and an energy threshold for structural change in said bulk, comprising the step of:

(a) controllably focusing ultrashort laser pulse in the bulk of said transparent material of energy above said energy threshold so as to produce a plasma therewithin that acts to fabricate permanent structures of high-contrast refractive index therewithin having regularly-shaped walls that are free of cracks in the bulk about each said permanent structure;
and
(b) patterning the same so as to record information of predetermined type therewithin.

A method providing optical information storage in transparent materials, comprising the steps of:

(a) selecting a transparent material having a material-dependent energy gap, a bulk and an energy threshold for structural change in said bulk to serve as an information storage medium;
(b) selecting a laser to provide a laser write beam with a photon energy less than the energy gap of said transparent material so that the laser write beam is substantially transparent thereto;
(c) selecting information of predetermined type to be written;
(d) resolving the information of predetermined type to be written as a pattern of plural information elements that is representative of the information to be written;
(e) defining inside the bulk of the transparent storage material a pattern of locations that correspond to the pattern of the information elements into which the information of predetermined type has been resolved;
and
(f) writing each information element to another location in the bulk of the transparent storage material by so optically focusing the laser write beam at each such location and by so delivering at least one ultrashort pulse of energy thereto of energy above said energy threshold for structural change in said bulk as to cause the bulk of the transparent material at each such location to non-linerly absorb the energy of the pulse, by at least one of the mechanisms of multiphoton ionization and avalanche ionization, producing thereby a localized plasma enclosed in the bulk of the material surrounding each such location, which plasma so alters the bulk of the transparent material surrounding each location as to permanently change the refractive index thereof, fabricating a permanent structure having regularly-shaped walls at each such location free of cracks in the bulk about each said permanent structure.

4 more elements

A digital optical information storage and retrieval system, comprising:

a transparent, solid storage medium having an interior region defining a bulk comprised of a plurality of locations where binary information is to be written and having an energy threshold for structural change in the bulk;
means for providing a laser write beam substantially transparent to said transparent, solid storage medium;
means for focusing the laser write beam along a path to a point inside of said interior region where information is to be written;
means for so displacing said point as to cause it to coincide with different ones of said locations of said interior region where binary information is to be written inside of said interior region of said transparent, solid storage medium;
means coupled to the laser write beam and responsive to binary information to be written and cooperative with said displacing and said focusing means for delivering energy by said beam that is above said energy threshold for structural change in the bulk producing a plasma at each said location that acts to fabricate a permanent sub-micron-diameter voxel of high-contrast refractive index at each said location in said interior region of said transparent, solid storage medium that is representative of said binary information;
and
optical means for detecting said permanent sub-micron-diameter voxels formed in said interior region at said locations of said transparent, solid storage medium to read said binary information.

4 more elements

Dependencies are inferred from the claim text.

Method and apparatus providing 2-D/3-D optical information storage and retrieval in transparent materials

Life of this patent

Method and apparatus providing 2-D/3-D optical information storage and retrieval in transparent materials

Life of this patent

Abstract

Claims45