Process for fabrication of high reflectors by reversal of layer sequence and application thereof

• US 20050063061A1
• Filed: 08/12/2004
• Published: 03/24/2005
• Est. Priority Date: 08/12/2003
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Wada, Kazumi, Akiyama, Shoji, Kaertner, Franz X., Grawert, Felix Jan
• Granted Patent: US 7,190,524 B2
• Time in Patent Office: Days
• US Class Current: 359/586
• CPC Class Codes: G02B 5/0833 comprising inorganic materials only

Abstract

An optical reflector includes an optical reflective element that comprises alternating layers of high and low index layers. A new substrate is bonded on the optical reflective element. The sequence of layers in the reflective element is reversed in order such that the layers grown first with lowest surface roughness are exposed to the highest electric field strength, and the layer grown last, of highest roughness, are buried deep in the multilayer stack.

Claims

1. An optical reflector comprising:

an optical reflective element that includes alternating layers of high and low index layers; and

a new substrate that is bonded on said optical reflective element, wherein

the sequence of layers in the reflective element is reversed in order such that the layers grown first with lowest surface roughness are exposed to the highest electric field strength, and the layer grown last, of highest roughness, are buried deep in the multilayer stack.

2. The optical reflector of claim 1, wherein said high index layers comprise of Si, doped Si, Si-compounds such as Si(x)Ge(1−

x), Ge, or other heat or electrically conductive materials.

3. The optical reflector of claim 1, wherein said low index layers comprise of SiO2, Si(x)O(y), SiN, ITO, or other heat or electrically conductive materials.

4. The optical reflector of claim 1, wherein said substrate comprises a Si wafer.

5. The optical reflector of claim 1, wherein said substrate comprises a quartz wafer or wafers made of sapphire, silicon nitride, SiC, GaN, BeO, BP, AlN, or AlP.

6. The optical reflector of claim 1, wherein said substrate comprises a germanium wafer.

7. The optical reflector of claim 1 further comprising a protective layer that comprises SiN.

9. The method of claim 1, wherein said high index layers comprise of Si, doped Si, Si-compounds such as Si(x)Ge(1−

x), Ge, or other heat or electrically conductive materials.

19. The method of claim 1, wherein said high index layers comprise of Si, doped Si, Si-compounds such as Si(x)Ge(1−

x), Ge, or other heat or electrically conductive materials.

8. A method of forming an optical reflector comprising:

providing a first semiconductor substrate;

forming on said substrate optical reflective elements that are comprised of alternating layers of high and low index layers;

forming a second substrate on the top optical reflective element;

removing said first semiconductor substrate; and

reversing the order of the layers in the multilayer stack.

10. The method of claim 8, wherein said low index layers comprise of SiO2, Si(x)O(y), SiN, ITO, or other heat or electrically conductive materials.

11. The method of claim 8, wherein said first semiconductor substrate comprises a Si wafer.

12. The method of claim 8, wherein said first semiconductor substrate comprises a quartz wafer or wafers made of sapphire, silicon nitride, SiC, GaN, BeO, BP, AlN, or AlP.

13. The method of claim 8, wherein said first semiconductor substrate comprises a germanium wafer.

14. The method of claim 8 further comprising a protective layer that comprises SiN.

15. The method of claim 8, wherein said second substrate comprises a Si wafer.

16. The method of claim 8, wherein said second substrate comprises a quartz wafer.

17. The method of claim 8, wherein said second substrate comprises a germanium wafer.

18. A method of forming an optical reflector comprising:

providing a first semiconductor substrate;

forming on said substrate optical reflective elements that are comprised of alternating layer of high and low index layers;

forming a second semiconductor substrate on the top optical reflective element;

removing a portion of said first semiconductor substrate; and

reversing the order of the layers in the multilayer stack.

20. The method of claim 18, wherein said low index layers comprise of SiO2, Si(x)O(y), SiN, ITO, or other heat or electrically conductive materials.

21. The method of claim 18, wherein said first semiconductor substrate comprises a Si wafer.

22. The method of claim 18, wherein said first semiconductor substrate comprises a quartz wafer or wafers made of sapphire, silicon nitride, SiC, GaN, BeO, BP, AlN, or AlP.

23. The method of claim 18, wherein said first semiconductor substrate comprises a germanium wafer.

24. The method of claim 18 further comprising a protective layer that comprises SiN.

25. The method of claim 18, wherein said second semiconductor substrate comprises a Si wafer.

26. The method of claim 18, wherein said second semiconductor comprises a quartz wafer.

27. The method of claim 18, wherein said first semiconductor comprises a germanium wafer.

28. An optical device comprising:

an optical reflective element that includes alternating layers of high and low index layers; and

a new substrate that is bonded on said optical reflective element, wherein

the sequence of layers in the reflective element is reversed in order such that the layers grown first with lowest surface roughness are exposed to the highest electric field strength, and the layer grown last, of highest roughness, are buried deep in the multilayer stack.

29. The optical reflector of claim 28, wherein said high index layers comprise of Si, doped Si, Si-compounds such as Si(x)Ge(1−

x), Ge, or other heat or electrically conductive materials.

30. The optical reflector of claim 28, wherein said low index layers comprise of SiO2, Si(x)O(y), SiN, ITO, or other heat or electrically conductive materials.

31. The optical reflector of claim 28, wherein said substrate comprises a Si wafer.

32. The optical reflector of claim 28, wherein said substrate comprises a quartz wafer or wafers made of sapphire, silicon nitride, SiC, GaN, BeO, BP, AlN, or AlP.

33. The optical reflector of claim 28, wherein said substrate comprises a germanium wafer.

34. The optical reflector of claim 28 further comprising a protective layer that comprises SiN.

35. The optical device of claim 28, wherein said device is configured to be an optical beam splitter.

36. The optical device of claim 28, wherein said device is configured to be an output coupler.