All-optical, flat-panel display system

• US 6,028,977 A
• Filed: 11/08/1996
• Issued: 02/22/2000
• Est. Priority Date: 11/13/1995
• Status: Expired due to Fees

• Current Assignee: Moriah Technologies Incorporated
• Original Assignee: Moriah Technologies Incorporated
• Inventors: Newsome, Edward E.
• Primary Examiner(s): Lee, John D.
• Application Number:
  US08/745,941
• Time in Patent Office: 1,201 Days
• Field of Search: 385/15-17, 385/115, 385/147, 385/901, 250/330, 250/483.1, 250/484.2, 250/484.4, 313/483, 313/498, 313/505, 313/510, 345/55, 345/81, 345/84, 40/542-544
• US Class Current: 385/147
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/0126 Opto-optical modulation, i.e. control of one light beam by another light beam, not otherwise provided for in this subclass
• CPC Class Codes: G02F 2/02 Frequency-changing of light, e.g. by quantum counters
• CPC Class Codes: G09F 9/33 being semiconductor devices, e.g. diodes
• CPC Class Codes: H01S 3/00 Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range semiconductors lasers H01S5/00
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

An all-optical flat panel display system is based on the generation of photoluminescence within a doped, optical waveguide display matrix. Color photoluminescence is produced through an infrared, two-step photonic upconversion process and the subsequent radiative emission process. Established principles of solid-state laser design and electronic upconversion in a host glass substrate are applied. The present photoluminescent display technology provides for flat-panel display systems having luminous output efficiencies approaching 67 lumens/Watt. That efficiency increase results from employing efficient, innovative photoluminescent phosphors and from an optical cavity architecture which enhances the three physical process (row excitation, column excitation and spontaneous output emission) operating inside the pixel. The present system is thinner, lighter weight, more power efficient and more cost competitive to produce than existing technologies. Further advantages realized by the present system include high readability in varying lighting conditions, viewing angle independence, size scalability without brightness and color quality sacrifice, rugged solid-state construction, vibration and thermal insensitivity and size independence. The present invention has potential applications in military, personal computing and digital HDTV systems, multi-media, medical and broadband imaging displays and large-screen display systems. Defense applications may range from full-color, high-resolution, see-through binocular displays to 60 inch digital command center displays.

Claims

1. A flat-panel display apparatus comprising a matrix having an array of intersecting and generally perpendicular row waveguides and column waveguides, wherein intersections of the row waveguides and the column waveguides are doped with a photo-active material to form photoluminescent pixels at the intersections of the row waveguides with the column waveguides, and independently selectable photonic power sources for delivering photonic power to selected pixels through the row waveguides and the column waveguides.

2. The apparatus of claim 1, wherein the photonic power sources are selected from the group consisting of semiconductor lasers, light-emitting diodes and miniature solid-state lasers.

3. The apparatus of claim 1, wherein the photonic power is provided at infrared wavelengths.

4. The apparatus of claim 1, wherein the photonic power sources further comprise (N+M) power sources, where N is a number of row waveguides and M is a number of column waveguides.

5. The apparatus of claim 1, wherein the photonic power sources further comprise pump sources for selecting pixels and upconversion sources for selecting luminescent qualities of the selected pixels.

6. The apparatus of claim 5, wherein the pump sources deliver photonic power to the pixels through row waveguides, and wherein the upconversion sources deliver photonic power to the pixels through the column waveguides.

7. The apparatus of claim 5, wherein the upconversion sources and the pump sources deliver photonic power to the pixels through the column waveguides.

8. The apparatus of claim 1, wherein the waveguides are made of materials selected from the group consisting of transparent fluoride crystals and glass, and wherein the photo-active material further comprises materials selected from the group consisting of rare-earth ions, transition metals and combinations thereof.

9. The apparatus of claim 1, wherein the matrix further comprises a substrate, an active layer formed on the substrate, a reflector layer positioned between the substrate and the active layer and a metalization layer positioned on an undersurface of the active layer, and wherein the row waveguides, the column waveguides and the photoluminescent pixels are formed in the active layer.

10. The apparatus of claim 9, wherein the substrate is made of a material selected from the group consisting of glass and polymers.

11. The apparatus of claim 10, wherein the substrate is made of glass selected from the group consisting of silica glasses, heavy metal, phosphate glasses, oxide glasses and fluoride glasses, the fluoride glasses further comprising zirconium fluoride, barium fluoride, strontium fluoride and lithium fluoride.

12. The apparatus of claim 10, wherein the row waveguides and the column waveguides are channel waveguides.

13. The apparatus of claim 9, wherein the substrate, row waveguides and column waveguides are made of low loss glass materials.

14. The apparatus of claim 1, wherein the row waveguides have spatial geometries for propagating streams of photonic power having first wavelengths, wherein the column waveguides have spatial geometries for propagating streams of photonic power having second wavelengths and for rejecting streams of photonic power having the first wavelengths, and wherein the first wavelengths are greater than the second wavelengths.

15. The apparatus of claim 1, wherein the row waveguides have spatial geometries for propagating streams of photonic power having first wavelengths, wherein the column waveguides have spatial geometries for propagating streams of photonic power having second wavelengths and for rejecting streams of photonic power having the first wavelengths, and wherein the first wavelengths are less than the second wavelengths.

16. The apparatus of claim 1, wherein the intersections of the row waveguides and column waveguides are orthogonal.

17. The apparatus of claim 1, wherein the column waveguides and row waveguides are of different geometric dimensions for minimizing row-to-column power coupling.

18. The apparatus of claim 1, wherein the photo-active material includes dopants selected from the group consisting of rare-earth ions, transition metals and combinations thereof.

19. The apparatus of claim 18, wherein the dopants are selected from the group consisting of erbium, holmium, thulium, praseodymium, neodymium, ytterbium, ytterbium:

erbium, ytterbium;

thulium, thulium;

praseodymium, chromium, thallium, manganese, vanadium, iron, cobalt, nickel, chromium;

neodymium and chromium;

erbium.

20. The apparatus of claim 1, wherein the photonic power sources are monolithically integrated onto the matrix.

21. The apparatus of claim 1, wherein the photonic power sources are coupled to the matrix by fiber-optical connections.

22. The apparatus of claim 1, wherein the photonic power sources further comprise pump sources for selecting pixels and upconversion sources for selecting luminescent qualities of the selected pixels, and further comprising a digital control connected to the upconversion sources for modulating luminance and color characteristics of the pixel, the control selected from the group consisting of an analog or continuous modulator, a digital pulse width modulator, a digital frequency or pulse rate modulator and a digital binary modulator.

23. The apparatus of claim 1, wherein the matrix further comprises a substrate having an active layer, wherein the intersecting row waveguides and column waveguides and pixels are provided in the active layer, wherein the pixels further comprise cells surrounded by side walls to form an optical cavity, and further comprising a distributed Bragg reflector layer positioned between the substrate and the waveguides and pixel cells and a metalization layer positioned on an underside of the cells.

24. The apparatus of claim 23, wherein the substrate functions as a cladding, wherein the waveguides have cores, wherein the waveguide cores and the substrate are made of silicon oxide, and wherein the optical cavity is made of glass-based BIZYT:

Yb³⁺ --Pr³⁺ phosphor.

25. The apparatus of claim 24, wherein a refractive index of the substrate is less than refractive indices of the waveguide cores.

26. The apparatus of claim 1, wherein the matrix further comprises cavities coupled to the waveguides, the cavities positioned at corners where row waveguide and column waveguides intersect, and wherein the cavities are doped with photo-active material.

27. The apparatus of claim 1, wherein the matrix is made of BIZYT glass, and wherein the photo-active material is trivalent praseodymium.

28. A method for converting signals into light images comprising the steps of providing a display having an array of intersecting row waveguides and column waveguides, doping intersecting regions of the waveguides with a photo-active material, selecting pixels by delivering photonic power to selected pixels through the row waveguides, exciting the selected pixels into non-radiative, intermediate metastable states, delivering photonic power to the selected pixels through the column waveguides, and exciting the selected pixels into visible photoluminescent states.

29. The method of claim 28, wherein exciting the pixels into non-radiative, intermediate metastable states further comprises creating localized, electronic population excitations at the selected pixels.

30. The method of claim 28, wherein exciting the pixels into non-radiative, intermediate metastable states further comprises bombarding electrons in the selected pixels with photons and exciting the electrons from ground level states to first excited, metastable states, and wherein exciting the selected pixels into visible photoluminescent states further comprises bombarding the electrons in the first excited states, upconverting the electrons to second, higher energy, non-metastable states, and allowing the electrons to decay spontaneously to the ground level for producing localized photoluminescence.

31. The method of claim 28, wherein providing a display further comprises providing a substrate and forming intersecting row waveguides and column waveguides in the substrate using photolithographic techniques.

32. The method of claim 28, wherein delivering photonic power to the selected pixels through the column waveguides further comprises controlling photoluminescent characteristics of the selected pixels.

33. The method of claim 32, wherein the characteristics are selected from the group consisting of intensity, brightness and color.

34. The method of claim 32, wherein controlling photoluminescent characteristics of the selected pixels further comprises digitally controlling photonic power sources by a modulation technique selected from the group consisting of analog or continuous modulation, digital pulse width modulation, digital frequency or pulse rate modulation and digital binary modulation.

35. The method of claim 28, wherein exciting the selected pixels into visible photoluminescent states further comprises activating the selected pixels on a pixel-by-pixel basis.

36. The method of claim 28, wherein providing a display further comprises manufacturing a display matrix having intersecting waveguides and photoluminescent pixels using a technique selected from the group consisting of ion exchange, flame hydrolysis deposition, vapor deposition and thin film techniques.

37. The method of claim 28, wherein providing a display further comprises depositing two successive glass particle layers of buffer and core by flame hydrolysis, consolidating the glass layers by applying heat, creating waveguides in the consolidated glass by RF magnetron sputtering, photolithographic pattern definition and reactive ion etching and covering the consolidated glass having the waveguides with silicon oxide over-cladding.