Multi-cavity Fabry-Perot ambient light filter apparatus

• US 7,521,666 B2
• Filed: 07/06/2005
• Issued: 04/21/2009
• Est. Priority Date: 02/17/2005
• Status: Active Grant

• Current Assignee: Capella Microsystems, Corp.
• Original Assignee: Capella Microsystems, Inc. (Vishay Intertechnology Incorporated)
• Inventors: Tsang, Koon Wing
• Primary Examiner(s): Lee; John R
• Application Number:
  US11/174,455
• Publication Number:
  US 20060180886A1
• Time in Patent Office: 1,385 Days
• Field of Search: 250/226, 257/432, 359/359, 359/360
• US Class Current: 250/226
• CPC Class Codes: G02B 5/282 reflecting for infrared and transparent for visible light, e.g. heat reflectors, laser protection
• CPC Class Codes: G02B 5/288 comprising at least one thin film resonant cavity, e.g. in bandpass filters
• CPC Class Codes: H01L 27/14621 Colour filter arrangements
• CPC Class Codes: H01L 31/02162 for filtering or shielding light, e.g. multicolour filters for photodetectors

Abstract

The present invention provides a multi-cavity Fabry-Perot ambient light filter apparatus. The multi-cavity Fabry-Perot ambient light filter apparatus comprises a plurality of Fabry-Perot cavities, each of the plurality of Fabry-Perot cavities covering one of a plurality of photodiodes; wherein each of the plurality of Fabry-Perot cavities has two partially reflective layers and one interferometric layer sandwiching between the two partially reflective layers, and shares one of the two partially reflective layers with a neighboring Fabry-Perot cavity and thereby stair stacking with the neighboring Fabry-Perot cavity. The plurality of Fabry-Perot cavities are capable of blocking the ambient light except for a wavelength spectrum that is recognizable for human eyes, thereby effectively accomplishes excellent IR blocking from non-visible light spectra.

Claims

1. A multi-cavity Fabry-Perot ambient light filter apparatus comprising:

a plurality of Fabry-Perot cavities, each of the plurality of Fabry-Perot cavities covering one of a plurality of photodiodes;

wherein each of the plurality of Fabry-Perot cavities has two partially reflective layers and one interferometric layer sandwiched between the two partially reflective layers, and shares one of the two partially reflective layers with a neighboring Fabry-Perot cavity;

each of said plurality of Fabry-Perot cavities disposed to form a stepped and stacked formation with the neighboring Fabry-Perot cavity.

2. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 1, wherein thicknesses of the interferometric layers are different from one another, thereby producing different spectral responses among the plurality of Fabry-Perot cavities.

3. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 2, wherein at least one of the plurality of Fabry-Perot cavities is capable of blocking infrared portions of the ambient light except for a wavelength region that is recognizable by human eyes.

4. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 3, wherein the wavelength region is chosen from a group consisting of a red-wavelength spectrum, a green-wavelength spectrum, a blue-wavelength spectrum, a cyan-wavelength spectrum, a magenta-wavelength spectrum and a yellow-wavelength spectrum.

5. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 1, wherein the partially reflective layers comprise silver thin films.

6. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 1, wherein the interferometric layers comprise silicon nitride thin films.

7. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 6, wherein the silicon nitride thin films comprise Si₃N₄.

8. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 1, wherein a bottom spacer layer is deposited under each of the plurality of Fabry-Perot cavities.

9. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 1, wherein a top moisture-protective layer is deposited on each of the plurality of Fabry-Perot cavities.

10. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 1, wherein the multi-cavity Fabry-Perot ambient light filter apparatus is made according to Complementary Metal Oxide Semiconductor (CMOS) technology, bipolar technology, or Bi-Complementary Metal Oxide Semiconductor (BiCMOS) technology.

11. A multi-cavity Fabry-Perot ambient light filter apparatus comprising:

a first Fabry-Perot cavity, having a first partially reflective layer, a second partially reflective layer and a first interferometric layer deposited between the first partially reflective layer and the second partially reflective layer; and

a second Fabry-Perot cavity, having a third partially reflective layer, a fourth partially reflective layer and a second interferometric layer deposited between the third partially reflective layer and the fourth partially reflective layer;

wherein the second Fabry-Perot cavity is forms a stepped stack on the first Fabry-Perot cavity such that the second partially reflective layer and the third partially reflective layer form a shared first common partially reflective layer, and the first partially reflective layer and the fourth partially reflective layer are physically distinct partially reflective layers.

12. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 11, further comprising:

a third Fabry-Perot cavity, having a fifth partially reflective layer, a sixth partially reflective layer and a third interferometric layer deposited between the fifth partially reflective layer and the sixth partially reflective layer;

wherein the third Fabry-Perot cavity forms a stepped stack on the second Fabry-Perot cavity such that the fourth partially reflective layer and the fifth partially reflective layer form a shared second common partially reflective layer, and the third partially reflective layer and the sixth partially reflective layer are physically distinct partially reflective layers.

13. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 12, wherein spectral responses of the first Fabry-Perot cavity, the second Fabry-Perot cavity and the third Fabry-Perot cavity are different.

14. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 13, wherein the spectral response of the first Fabry-Perot cavity comprises a red-wavelength spectrum, the spectral response of the second Fabry-Perot cavity comprises a green-wavelength spectrum, and the spectral response of the third Fabry-Perot cavity comprises a blue-wavelength spectrum.

15. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 14, wherein the red-wavelength spectrum comprises a peak value near 650 nm.

16. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 14, wherein the green-wavelength spectrum comprises a peak value near 550 nm.

17. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 14, wherein the blue-wavelength spectrum comprises a peak value near 450 nm.

18. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 13, wherein the spectral response of the first Fabry-Perot cavity comprises a cyan-wavelength spectrum, the spectral response of the second Fabry-Perot cavity comprises a magenta-wavelength spectrum, and the spectral response of the third Fabry-Perot cavity comprises a yellow-wavelength spectrum.

19. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 12, wherein the thicknesses of the first interferometric layer, the second interferometric lay and the third interferometric layer are different.

20. The multi-cavity Fabry-Perot ambient light filter apparatus of claim 12, wherein the first Fabry-Perot cavity, the second Fabry-Perot cavity and the third Fabry-Perot cavity are made according to Complementary Metal Oxide Semiconductor (CMOS) technology, bipolar technology, or Bi-Complementary Metal Oxide Semiconductor (BiCMOS) technology.