Transparent metallo-dielectric photonic band gap structure

• US 6,262,830 B1
• Filed: 09/16/1997
• Issued: 07/17/2001
• Est. Priority Date: 09/16/1997
• Status: Expired due to Fees

• Current Assignee: Michael Scalora
• Original Assignee: Michael Scalora
• Inventors: Scalora, Michael
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Lester, Evelyn A.
• Application Number:
  US08/931,756
• Time in Patent Office: 1,400 Days
• Field of Search: 359/248, 359/344, 359/580, 359/585, 359/586-588, 359/589, 343/909, 343/911.R, 372/43, 372/45, 257/451
• US Class Current: 359/248
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 2202/32 Photonic crystals

Abstract

A transparent metal structure permits the transmission of light over a tunable range of frequencies, for example, visible light, and shields ultraviolet light and all other electromagnetic waves of lower frequencies, from infrared to microwaves and beyond. The transparent metal structure comprises a stack of alternating layers of a high index material and a low index material, at least one of the materials being a metal. By carefully choosing the thickness of the second material, the transparent window can be tuned over a wide range of frequencies.

Claims

1. A transparent metal photonic band gap device, comprising:

a first metal layer having a first metal thickness;

a first interstitial layer having a first interstitial thickness formed on said first metal layer;

a second metal layer having a second metal thickness formed on said first interstitial layer;

a second interstitial layer having a second interstitial thickness formed on said second metal layer;

a third metal layer having a third metal thickness formed on said second interstitial layer, wherein said thicknesses of said metal and interstitial layers are selected to form a photonic band gap structure having a transmission resonance range on at least one side of a photonic band gap range, the photonic band gap structure permitting transmission of light at wavelengths in a first wavelength range within the transmission resonance range and suppressing transmission of light at wavelengths in a second wavelength range within the photonic band gap range.

2. The device of claim 1, further comprising at least one of:

third interstitial layer having a third interstitial thickness formed on said third metal layer; and

a substrate to support said first metal layer.

3. The device of claim 2, wherein said substrate is transparent.

4. The device of claim 1, wherein said first, second, and third metal layers are selected from a group comprising all transition metal.

5. The device of claim 1, wherein said first, second, and third metal layers are selected from a group comprising silver, aluminum, copper, and gold.

6. The device of claim 1, wherein said first, second, and third metal layers are silver.

7. The device of claim 1, wherein said first, second, and third metal thicknesses are each between approximately 2.5 to 5 nanometers (nm) and approximately 40 to 60 nm.

8. The device of claim 1, wherein said first and second interstitial layers are selected from a group comprising semiconductor materials, ordinary dielectrics, and a combination of semiconductor and dielectric materials.

9. The device of claim 1, wherein said first and second interstitial layers comprise Magnesium Fluoride (MgF₂).

10. The device of claim 1, wherein said first and second interstitial thicknesses are each between approximately 2.5 to 5 nanometers (nm) and 300 to 500 nm.

11. The device of claim 1, wherein said first wavelength range comprises the visible wavelength region of the electromagnetic spectrum.

12. The device of claim 1, wherein said first wavelength region comprises the ultraviolet wavelength region of the electromagnetic spectrum.

13. The device of claim 1, wherein said first wavelength region comprises the infrared wavelength region of the electromagnetic spectrum.

14. The device of claim 1, wherein said second wavelength range comprises the infrared (IR) region of the electromagnetic spectrum.

15. The device of claim 1, wherein said second wavelength range comprises the ultraviolet (UV) region of the electromagnetic spectrum.

16. The device of claim 1, wherein said second wavelength range comprises the infrared region to the microwave region of the electromagnetic spectrum.

17. The device of claim 1, wherein said second wavelength range comprises the visible region of the electromagnetic spectrum.

18. The device of claim 2, further comprising:

a plurality of metal layers having said first metal thickness, wherein said second and third metal thicknesses equal said first metal thickness; and

a plurality of interstitial layers having said first interstitial thickness, wherein said second and third interstitial thicknesses equals said first interstitial thickness, wherein said plurality of metal and interstitial layers are arranged in an alternating manner, and wherein said plurality of metal and interstitial layers corresponds to said first and second wavelength ranges.

19. The device of claim 1, further comprising:

a voltage source, coupled to said interstitial layers, to create an applied electromagnetic field, wherein an optical path length of said interstitial layers is altered.

20. The device of claim 19, wherein the first transmission range is tunable.

21. The device of claim 1, wherein the first, second, and third metals layers are silver, to transmit a selected magnitude of UV radiation.

22. The device of claim 1 having a dynamically tunable first transmission range, wherein incident photonic signals interact with said first and second interstitial layers to alter an optical path length of said first and second interstitial layers.

23. The device of claim 1, wherein each of said first to third metal layers comprises silver and the sum of said first to third metal thicknesses is greater than 33 nm.

24. The device of claim 1, wherein the device can have thicknesses selected such that said first wavelength range comprises at least visible wavelengths between 400 nm to 700 nm;

and said second wavelength range comprises at least one of UV, IR or microwave regions of the electromagnetic spectrum.

25. The device of claim 1, further comprising at least one additional metal layer wherein each first to third metal layer and additional metal layer comprises silver, the sum of said first to third metal thicknesses and each additional metal layer thickness being equal to or greater than 100 nm;

whereby, the device has a conductivity such that the device can be substituted for indium tin oxide in liquid crystal applications.

26. The device of claim 1, wherein the device has at least of one a total of 20 silver layers and 40 silver layers.

27. The device of claim 1, wherein said transmission of light at wavelengths in said first wavelength range corresponds to at least 40 percent transmission and transmission of light at wavelengths in said second wavelength range corresponds to no more than 10⁻

5 transmission.

28. The device of claim 1, wherein said first wavelength region comprises an infrared wavelength region including near infrared wavelength between 3-5 microns.

29. The device of claim 1, wherein said first wavelength region comprises an infrared wavelength region including far infrared wavelength between 8-12 microns.

30. A transparent metal photonic band gap device comprising:

a first metal layer having a first metal thickness;

a first interstitial layer having a first interstitial thickness formed on said first metal layer;

a second metal layer having a second metal thickness formed on said first interstitial layer;

a second interstitial layer having a second interstitial thickness formed on said second metal layer;

a third metal layer having a third metal thickness formed on said second interstitial layer, wherein an arrangement of said metal and interstitial lavers exhibits a photonic band gap structure that permits transmission of light at wavelengths in a first wavelength range and suppresses transmission of light at wavelengths in a second wavelength range;

further comprising at least one of;

a third interstitial layer having a third interstitial thickness formed on said third metal layer; and

a substrate to support said first metal layer;

wherein said first, second, and third metal layers are silver and said first, second, and third metal layer thicknesses are each approximately 27.5 nm, wherein said first and second interstitial layers are MgF₂ and said first and second interstitial thicknesses are each approximately 156 nm, wherein said first wavelength range comprises the group of wavelengths between approximately 530 and 560 nm, wherein the second wavelength range comprises the IR and microwave wavelength regions, and wherein said transmission of light at wavelengths in said first wavelength range corresponds to approximately 40 percent transmission and said transmission of light at wavelengths in said second wavelength range corresponds to approximately 10<sup>−

5</sup> transmission.

31. An optical filter, comprising:

a plurality of metal layers, each of said plurality of metal layers having a predetermined thickness; and

a plurality of interstitial layers, each of said plurality of interstitial layers having a predetermined thickness, wherein said plurality of metal layers and said plurality of interstitial layers are arranged in an alternating manner and each of said predetermined thicknesses are selected to form a photonic band gap (PBG) structure, wherein said PBG structure transmits light at wavelengths in a first wavelength range and wherein said PBG structure reflects light at wavelengths in a second wavelength range, and wherein said predetermined thicknesses of said plurality of metal layers and said plurality of interstitial layers correspond to said first and second wavelength ranges.

32. A method for creating a transparent metal photonic band gap device, comprising the steps of:

(1) forming a first metal layer to a transparent substrate, wherein the first metal layer has a first metal layer thickness;

(2) forming a first interstitial layer on the first metal layer, wherein the first interstitial layer has a first interstitial thickness, wherein a structure comprising the first metal layer and the first interstitial layer forms a first period;

(3) forming a second period comprising a second metal layer and a second interstitial layer onto the first period; and

(4) forming a third period comprising a third metal layer and a third interstitial layer onto the second period, wherein each of said thicknesses of said metal and interstitial layers is selected to form a photonic band gap structure permitting transmission of light at wavelengths in a first selected wavelength range and suppressing transmission of light at wavelengths in a second selected wavelength range.

33. The method of claim 32, further comprising the step of:

(5) forming a predetermined number of additional periods onto the device, wherein a greater number of periods corresponds to an increased first selected wavelength range.

34. The method of claim 32, further comprising the step of:

(5) independently modifying the metal and interstitial layer thicknesses to optimize the transmission in the first and second selected wavelength ranges.

35. A method for producing a transparent metal photonic band gap device, comprising the steps of:

(1) selecting a total amount of metal that permits transmission of light at wavelengths in a first selected wavelength range;

(2) dividing the total amount of metal into a selected number of metal layers, wherein each metal layer has a corresponding metal thickness; and

(3) interposing an interstitial layer between each metal layer, wherein each interstitial layer has a corresponding interstitial thickness corresponding to suppressing transmission of light at wavelengths in a second selected wavelength range, to form the device having a photonic band gap structure.

36. The method of claim 35, further comprising the step of:

(4) altering the metal and interstitial layer thicknesses to alter the second selected wavelength range.

37. A method for producing a transparent metal periodically alternating photonic band gap device, comprising the steps of:

(1) forming a first period comprising a first metal layer and a first interstitial layer; and

(2) forming a selected number of additional periods onto the first period, wherein the selected number of additional periods and thicknesses of metal and interstitial layers in each period corresponds to a photonic band gap structure that permits transmission of light at wavelengths in a first selected range of wavelengths and suppresses transmission of light at wavelengths in a second selected range of wavelengths.

38. The method according to claim 37, further comprising the step of:

(3) increasing the additional number of periods formed on the first period to increase the first selected range of wavelengths.

39. A method for optimizing the transmission of a first selected range of wavelengths of a transparent metal photonic band gap shielding device that suppresses the transmission of a second selected range of wavelengths by a selected magnitude, comprising the steps of:

(1) choosing a total amount of metal comprising the shielding device;

(2) dividing the total amount of metal into a selected number of metal layers, wherein each metal layer has an individual metal layer thickness; and

(3) spacing each individual metal layer apart by a selected thickness to create a plurality of spacing regions, wherein said spacing corresponds to a photonic band gap structure of the shielding device and the first selected range of wavelengths.

40. The method of claim 39, further comprising the step of:

(4) interposing a plurality of interstitial layers into the spacing regions, wherein said interstitial layers are selected from the group comprising semiconductor materials, ordinary dielectrics, and a combination of semiconductor and dielectric materials.

41. The method of claim 40, further comprising the step of:

(5) selecting the metal layers from a group comprising all transition metals.

42. The method of claim 40, further comprising the step of:

(6) applying an external electromagnetic field to the interstitial layers to alter an optical path of said interstitial layers and tune the first selected range of wavelengths.

43. The method of claim 40, further comprising the step of:

(5) selecting the metal layers from a group comprising silver, copper, and gold.