Resonant reflector for use with optoelectronic devices

• US 6,782,027 B2
• Filed: 12/29/2000
• Issued: 08/24/2004
• Est. Priority Date: 12/29/2000
• Status: Expired due to Term

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Finisar Corporation (II-VI Incorporated)
• Inventors: Cox, James Allen, Morgan, Robert A.
• Primary Examiner(s): LEUNG, QUYEN PHAN
• Application Number:
  US09/751,422
• Publication Number:
  US 20030103542A1
• Time in Patent Office: 1,334 Days
• Field of Search: 372/43-50, 372/96
• US Class Current: 372/50.1
• CPC Class Codes: H01S 5/11 Comprising a photonic bandgap structure
• CPC Class Codes: H01S 5/18308 having a special structure for lateral current or light confinement
• CPC Class Codes: H01S 5/18319 comprising a periodical structure in lateral directions
• CPC Class Codes: H01S 5/18355 having a defined polarisation
• CPC Class Codes: H01S 5/18358 containing spacer layers to adjust the phase of the light wave in the cavity
• CPC Class Codes: H01S 5/18369 based on dielectric materials
• CPC Class Codes: H01S 5/18377 comprising layers of different kind of materials, e.g. combinations of semiconducting with dielectric or metallic layers
• CPC Class Codes: H01S 5/18388 Lenses
• CPC Class Codes: H01S 5/18397 Plurality of active layers vertically stacked in a cavity for multi-wavelength emission
• CPC Class Codes: H01S 5/4087 emitting more than one wavelength
• CPC Class Codes: H01S 5/423 having a vertical cavity

Abstract

An optoelectronic device that provides isolation between a resonant reflector and an adjacent conducting layer of the optoelectronic device. Isolation may be accomplished by providing a buffer or cladding layer between the resonant reflector and the adjacent conducting layer of the optoelectronic device. The cladding or buffer layer is preferably sufficiently thick, or has a sufficiently low refractive index relative to the refractive index of the waveguide of the resonant reflector, to substantially prevent energy in the evanescent tail of the guided mode in the waveguide from entering the adjacent conductive layer of the optoelectronic device.

Claims

1. An optoelectronic device having a top mirror and a bottom mirror, the top mirror and bottom mirror being at least partially conductive, the improvement comprising:

a resonant reflector positioned adjacent a selected one of the top or bottom mirrors, the resonant reflector having a waveguide and a grating configured such that a first-diffraction order wave vector of the grating substantially matches a propagating mode of the waveguide; and

a cladding or buffer layer positioned between the resonant reflector and the selected top or bottom mirror, the cladding or buffer layer being sufficiently thick, and/or having a sufficiently low refractive index relative to the refractive index of the waveguide, to substantially prevent energy in the evanescent tail of the guided mode in the waveguide from entering the selected top or bottom mirror.

2. An optoelectronic device according to claim 1, wherein cladding or buffer layer is non-conductive.

3. An optoelectronic device according to claim 1, wherein the cladding or buffer layer and the waveguide each have a refractive index, the refractive index of the cladding or buffer layer being substantially less than the refractive index of the waveguide.

4. An optoelectronic device according to claim 3, wherein the selected top or bottom mirror includes an adjacent layer that is positioned adjacent the cladding or buffer layer, the refractive index of the cladding or buffer layer being less than the refractive index of the adjacent layer.

5. An optoelectronic device according to claim 4, wherein the thickness of the cladding or buffer layer is thicker than the adjacent layer.

6. An optoelectronic device according to claim 5, wherein the thickness of the cladding or buffer layer depends on the refractive index difference between the cladding or buffer layer and the waveguide.

7. An optoelectronic device according to claim 2, wherein the cladding or buffer layer is a dielectric film.

8. An optoelectronic device according to claim 7, wherein the cladding or buffer layer is an aluminum oxide film.

9. An optoelectronic device according to claim 7, wherein the waveguide region includes AlGaAs.

10. An optoelectronic device according to claim 7, wherein the waveguide region includes a high refractive index dielectric.

11. An optoelectronic device according to claim 7, wherein the grating is a dielectric film.

12. An optoelectronic device according to claim 7, wherein the grating is a silicon oxide film.

13. An optoelectronic device according to claim 7, wherein the cladding or buffer layer functions as part of the resonant reflector.

14. A Vertical Cavity Surface Emitting Laser (VCSEL) or Resonant Cavity Photo Detector (RCPD), comprising:

a top mirror and a bottom mirror, with an active region therebetween;

a resonant reflector positioned adjacent at least one of the top mirror and/or bottom mirror, the resonant reflector including;

a waveguide; and

a grating film having two or more spaced grating regions separated by one or more spaced regions, the spaced regions of the grating film having a grating film thickness that is less than the grating film thickness of the grating regions, but greater than zero.

15. A resonant reflector according to claim 14, wherein selected optical properties of the resonant reflector are controlled by the grating film thickness of the spaced regions and grating regions.

16. A resonant reflector according to claim 15, wherein the spectral bandwidth of the resonant reflector is determined by the grating film thickness of the spaced regions and grating regions.

17. A resonant reflector according to claim 15, wherein each grating region has a lateral width, with the grating regions collectively having a grating period, the grating period minus the grating width defining a grating spacing between adjacent grating regions, the grating spacing divided by the grating period defining a grating fill factor, the grating fill factor being about 50%.

18. A monolithic transceiver having a light emitting device and a light receiving device, comprising:

providing a bottom mirror on a substrate, the bottom mirror being at least partially conductive;

providing an active region on the bottom mirror;

providing a top mirror on the active region, the top mirror being at least partially conductive;

providing a cladding or buffer layer on the top mirror, the cladding or buffer layer being non-conductive;

providing a waveguide on the cladding or buffer layer;

providing a grating layer above the waveguide, the waveguide and grating being configured such that a first-diffraction order wave vector of the grating substantially matches a propagating mode of the waveguide;

the cladding or buffer layer being sufficiently thick, or having a sufficiently low refractive index relative to the refractive index of the waveguide, such that energy in the evanescent tail of the guided mode in the waveguide is substantially prevented from entering the top mirror; and

the grating layer having a first etched grating structure above the light emitting device.

19. A monolithic transceiver according to claim 18, further comprising a second etched grating structure above the light receiving device.

20. A monolithic transceiver according to claim 18, wherein the grating layer does not have an etched grating structure above the light receiving device.

21. A monolithic transceiver according to claim 18, wherein the grating layer is removed above the light receiving device.

22. A device comprising:

a first substrate having a front side and a back side with at least part of an optoelectronic device formed on the front side;

a second substrate having a front side and a back side with a resonant reflector formed on the front side; and

the front side of the first substrate bonded to the front side of the second substrate; and

wherein the resonant reflector includes a waveguide and a grating.

23. A device according to claim 22, wherein the grating is positioned more toward the front side of the second substrate than is the waveguide.

24. A device according to claim 22, wherein the waveguide is positioned more toward the front side of the second substrate than is the grating.

25. A device comprising:

a first substrate having a front side and a back side with at least part of an optoelectronic device formed on the front side;

a second substrate having a front side and a back side with a resonant reflector formed on the front side; and

the front side of the first substrate bonded to the front side of the second substrate; and

wherein the front side of the first substrate is bonded to the front side of the second substrate via an optical epoxy.

26. A device according to claim 25, wherein the optical epoxy is non-conductive.

27. A device according to claim 26, wherein the waveguide and grating are configured such that a first-diffraction order wave vector of the grating substantially matches a propagating mode of the waveguide.

28. A device according to claim 27, wherein the optical epoxy is sufficiently thick, or has a sufficiently low refractive index relative to the refractive index of the waveguide, to substantially prevent energy in the evanescent tail of the guided mode in the waveguide from entering the first substrate.

29. A device comprising:

a first substrate having a front side and a back side with at least part of an optoelectronic device formed on the front side;

a second substrate having a front side and a back side with a resonant reflector formed on the front side;

the front side of the first substrate bonded to the front side of the second substrate; and

a collimating microlens positioned on the back side of the second substrate.

30. A device according to claim 29, wherein the collimating microlens is in registration with the resonant reflector and the optoelectronic device.

31. A device comprising:

a first substrate having a front side and a back side with at least part of an optoelectronic device formed on the front side;

a second substrate having a front side and a back side with a resonant reflector formed on the front side; and

the front side of the first substrate bonded to the first side of the second substrate; and

wherein the resonant reflector includes a grating.

32. A device comprising:

a first substrate having a front side and a back side with at least part of an optoelectronic device formed on the front side;

a second substrate having a front side and a back side with a resonant reflector formed on the front side; and

the front side of the first substrate bonded to the front side of the second substrate; and

wherein the resonant reflector includes a waveguide.