Data storage using light of spatially modulated phase and polarization
An optical data-storage system comprises a laser, an imaging optic, and associated computer logic. The laser is configured to emit a pulsed wavefront having uniform phase and polarization. The imaging optic is configured to modulate the phase and polarization of different portions of the wavefront by different amounts, and to diffract light from the different portions to a substrate with writeable optical properties. The logic is configured to receive data and to control modulation of the phase and polarization such that the light diffracted from the imaging optic writes the data to the substrate.
1. An optical data-storage system, comprising:
a laser configured to emit a sub-picosecond pulsed wavefront having uniform phase and polarization;
an imaging optic configured to modulate the phase and polarization of different portions of the wavefront by different amounts, and to diffract light from the different portions to a substrate with writeable optical properties, the imaging optic being configured to modulate the different portions of the wavefront to different near-field polarizations and to image the light to an array of substrate voxels at different far-field polarizations; and
operatively coupled to the imaging optic, logic configured to receive data and to control modulation of the phase and polarization such that the light diffracted from the imaging optic writes the data to the substrate.
2. The optical data-storage system of claim 1 wherein the data includes inequivalent first and second data values written simultaneously by the light diffracted from the imaging optic, wherein the first data value is written to a first voxel by light of a first far-field polarization, and wherein the second data value is written to a second voxel by light of a second far-field polarization.
3. The optical data-storage system of claim 2 wherein each data value written to the substrate is characterized by one of R≥1 different amplitude values of the diffracted light at each of Q≥1 different far-field polarizations.
4. The optical data-storage system of claim 3 wherein the each of Q≥1 different far-field polarization determines a slow axis orientation at the voxel where the data value is written, and wherein the one of R≥1 different amplitude values determines a retardance at the voxel where the data value is written.
5. The optical data-storage system of claim 1 wherein the substrate comprises glass.
6. The optical data-storage system of claim 1 wherein the pulsed wavefront comprises pulses of 100 femtoseconds or less.
7. The optical data-storage system of claim 1 wherein the imaging optic is a liquid-crystal spatial light modulator (LCSLM) having an array of pixel elements configured to modulate the phase and polarization of different portions of the wavefront by different amounts, and to diffract the light from the different portions to the substrate.
8. The optical data-storage system of claim 7 wherein the LCSLM includes two independently addressable electrodes per pixel element and is configured to modulate the phase independent of the polarization.
9. The optical data-storage system of claim 1 wherein the imaging optic is configured to modulate the phase in correlation with the polarization.
10. The optical data-storage system of claim 1 wherein the logic is configured to execute a holographic-design algorithm to control modulation of the phase and polarization.
11. An optical data-storage system, comprising:
a laser configured to emit a pulsed wavefront having uniform phase and polarization;
a liquid-crystal spatial light modulator (LCSLM) having an array of pixel elements configured to modulate the phase and polarization of different portions of the wavefront by different amounts, and to diffract light from the different portions to a substrate with writeable optical properties; and
operatively coupled to the LCSLM, logic configured to receive data and to control modulation of the phase and polarization such that the light diffracted from the LCSLM writes the data to the substrate,
wherein the LCSLM is configured to modulate the different portions of the wavefront to different near-field polarizations and to image the light to an array of substrate voxels at different far-field polarizations, wherein the data includes inequivalent first and second birefringence values written simultaneously by the light diffracted from the LCSLM, wherein the first birefringence value is written to a first voxel by light of a first far-field polarization, and wherein the second birefringence value is written to a second voxel by light of a second far-field polarization.
12. The optical data-storage system of claim 11 wherein the LCSLM is configured to modulate the phase in correlation with the polarization.
13. The optical data-storage system of claim 11 wherein the logic is configured to execute a holographic-design algorithm to control modulation of the phase and polarization.
14. The optical data-storage system of claim 13 wherein the holographic-design algorithm is based on a Gerchberg-Saxton algorithm.
15. The optical data-storage system of claim 13 wherein the holographic-design algorithm is based on a Direct Binary Search algorithm.
16. The optical data-storage system of claim 11 further comprising a polarization-modulating sheet arranged between the laser and the LCSLM, the polarization-modulating sheet comprising a tiling of cells arranged in registry with the pixel elements of the array, each cell configured to rotate the polarization of a portion of the wavefront passing through that cell.
17. An optical data-storage system, comprising:
a laser configured to emit a pulsed wavefront having uniform phase and polarization;
a liquid-crystal spatial light modulator (LCSLM) having an array of pixel elements configured to modulate the phase and polarization of different portions of the wavefront by different amounts, and to diffract light from the different portions to a substrate with writeable optical properties, each pixel element having first and second independently addressable electrodes; and
operatively coupled to the first and second electrodes of each pixel element, logic configured to receive data and to control modulation of the phase and polarization such that the light diffracted from the LCSLM writes the data to the substrate,
wherein an average voltage applied to the first and second electrodes of a pixel element of the LCSLM affects a phase of a first component of the portion of the wavefront passing through that element, and wherein a differential voltage between the first and second electrodes affects a phase of a non-parallel second component of the portion of the wavefront passing through that element.