High speed optical system

• US 6,961,489 B2
• Filed: 06/30/2003
• Issued: 11/01/2005
• Est. Priority Date: 06/30/2003
• Status: Expired due to Term

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Finisar Corporation (II-VI Incorporated)
• Inventors: Cox, James A., Chen, Bo Su
• Primary Examiner(s): Healy, Brian
• Assistant Examiner(s): Lepisto, Ryan
• Application Number:
  US10/610,256
• Publication Number:
  US 20040264854A1
• Time in Patent Office: 855 Days
• Field of Search: 385 31- 36, 350 9615- 9616, 350/96.18, 350/96.24, 350/96.26
• US Class Current: 385/33
• CPC Class Codes: G02B 6/32 having lens focusing means positioned between opposed fibre ends with lens being an integral part of the single fibre end G02B6/262
• CPC Class Codes: G02B 6/4206 Optical features G02B6/4207, G02B6/421 take precedence

Abstract

An optical system for high speed transmission of optical data. The system may condition light signals from a source for projection into an optical medium that is to convey the signals with high speed to another place. This conditioning may result in the light having an annular intensity distribution or profile. Much of the intensity of the light is near the periphery of the optical medium. This medium may be an optical fiber. This annular distribution may be attained with an optical element having a slope discontinuity or light from it being defocused to a certain extent at the optical medium. Either of these characteristics or both of them may used in the optical system so it can transmit light signals at very high rates.

Claims

1. A light transmission system comprising:

a light source;

an optical fiber; and

a transfer lens for conveying light emitted by said light source into said optical fiber; and

wherein;

an optical axis runs from said light source through said transfer lens onto said optical fiber;

said transfer lens has a first surface for receiving light from said light source;

said transfer lens has a second surface for exiting light received at the first surface from said light source, and launching the light into a first end face of a said optical fiber light; and

the second surface has a slope discontinuity proximate to the optical axis.

2. The system of claim 1, wherein the second surface of said transfer lens is shaped so that light launched into the end face of said optical fiber has an annular intensity profile on the first end face around the optical axis.

3. The system of claim 2, wherein the light launched into the first face of said optical fiber exits from a second face of said optical fiber having an annular intensity profile about a center of the second face of said optical fiber.

4. The system of claim 3, wherein light that exits the second face of said optical fiber has an encircled flux within a radius of about 4.5 microns at 30 percent or less of the total encircled flux within a radius of about 19 microns at 86 percent or more of the total encircled flux.

5. The system of claim 4, wherein a power distribution at the second end of said optical fiber is sufficient to achieve a 2000 MHz-Km bandwidth-distance product.

6. The system of claim 5, wherein said optical fiber is a 500 MHz-Km fiber.

7. The system of claim 6, wherein said optical fiber is a multimode fiber.

8. The system of claim 7, wherein said light source is a laser.

9. The system of claim 8, wherein said light source is a vertical cavity surface emitting laser (VCSEL).

10. The system of claim 9, wherein said VCSEL is a multi mode light source.

11. The system of claim 9, wherein said VCSEL is a single mode light source.

12. An optical system comprising:

an optical element having an input surface, an output surface, and an optical axis; and

an optical medium having an end proximate to the output surface of said optical element and an end distal to the output surface of said optical element, the optical medium configured to receive emitted light having a received annular intensity profile and transfer the light to the distal end such that the transferred light substantially retains the received annular intensity profile at the distal end; and

wherein;

the output surface has a continuous slope/curvature in an area approximately between a periphery of the output surface and a first distance from the optical axis; and

the output surface has a discontinuity in an area within a perimeter of the first distance for emitting light having an output annular intensity profile receivable at the proximate end of the optical medium.

13. An optical system comprising:

an optical element having an input surface and an output surface; and

an optical fiber having an input surface, an output surface with a center point; and

wherein;

the output surface of said optical element is proximate to the input surface of said optical fiber;

the output surface of said optical element has a shape and configuration such that for light input into the input surface of said optical element, the output surface of said fiber has an output of encircled flux;

no more than 30 percent of the output of encircled flux is within 4.5 microns from the center point; and

at least 86 percent of the output of encircled flux is within 19 microns from the center point.

14. An optical system comprising:

an optical fiber; and

an optical element having an input surface, and an output surface proximate to a first end of said optical fiber; and

wherein the output surface of said optical element is situated near the first end of said optical fiber, such that upon receipt of light by the input surface of said optical element, said optical element is defocused relative to the first end of said optical fiber so as to result in a distribution pattern of light having a lack of light at a center of the first end of said optical fiber.

15. The system of claim 14, wherein:

said optical fiber has a second end which emanates a distribution pattern of light upon receipt of light at the input surface of said optical element; and

the distribution pattern of light at the second end of said optical fiber has a lack of light at about a center of the second end of said optical fiber.

16. The system of claim 15, wherein the distribution pattern of light emanating from the second end of said optical fiber upon receipt of light at the input surface of said optical element comprises:

30 percent or less of the total light output within a radius of about 4.5 microns from the center; and

at least 86 percent of the total light output within a radius of about 19 microns from the center.

17. The system of claim 16, wherein, further comprising a light source for providing the light to the input surface of said optical element.

18. The system of claim 17, wherein said light source is a laser.

19. The system of claim 18, wherein said laser is a vertical cavity surface emitting laser.

20. The system of claim 19, wherein said optical fiber has an about 50 micron core and an about 125 micron cladding around the core.

21. The system of claim 14, wherein:

said optical element has an axicon-like function on at least one surface of said optical element.

22. The system of claim 21, wherein said optical element is a defocused well-corrected optic relative to the first end of said optical fiber.

23. The system of claim 22, wherein the defocused well-corrected optic provides a relatively dark spot on the first end of said optical fiber.

24. The system of claim 23, wherein the axicon-like function results from the at least one surface of said optical element having an aspheric surface with a slope-discontinuity proximate to an optical axis of said optical element.

25. The system of claim 24, wherein the dark spot is a spot of Arago.

26. An optical system comprising:

an optical fiber having a first end;

an optical element wherein said optical element is a defocused well-corrected optic relative to the first end of said optical fiber; and

wherein said defocused well-corrected optic projects light has an annular shaped intensity profile, and wherein substantially all of the projection of light having an annular shaped intensity profile is received within the first end of said optical fiber.

27. The optical system of claim 26, wherein said optical element has an axicon-like function on at least one surface of said optical element.

28. The optical system of claim 27, wherein the defocused well-corrected optic may provide a relatively dark spot on the first end of said optical fiber.

29. The system of claim 28, wherein the axicon-like function results from the at least one surface of said optical element having an aspheric surface with a slop-discontinuity proximate to an optical axis of said optical element.

30. The system of claim 29, wherein the dark spot is a dark spot of Arago.

31. An optical system comprising:

a light source;

an optical element having a first surface proximate to said light source and having a second surface;

an optical fiber having a first end proximate to the second surface of said optical element and having a second end;

wherein;

said optical element has the characteristic of receiving light from said light source and projecting the light with an annular amplitude distribution on to the first end of said optical fiber; and

said optical fiber has the characteristic of receiving the light projected from said optical element and projecting the light from the second end of said optical fiber with an annular power distribution.

32. The optical system of claim 31, wherein:

said light source is a laser; and

said optical fiber is multi-mode fiber.

33. The optical system of claim 32, wherein said laser is a single mode vertical cavity surface emitting laser.

34. The optical system of claim 32, wherein said laser is a multi-mode vertical cavity surface emitting laser.

35. The optical system of claim 32, wherein said optical element has at least one surface with a discontinuity in slope.

36. The optical system of claim 32, wherein the power annular distribution of the light from the second end of said optical fiber has the following characteristics:

thirty or less percent of the total power from the second end is from an area bordered by a perimeter of a radius of about 4.5 microns from a center of the second end of said optical fiber; and

eighty-six or more percent of the total power from the second end is from an area bordered by a perimeter of a radius of about 19 microns from the center of the second end of said optical fiber.

37. The optical system of claim 31,

wherein said optical element has a slope discontinuity on at least one surface.

38. The system of claim 37, wherein said optical element and said optical fiber are adjusted in position relative to each other so as to emphasize an annular distribution of the light received by the first end of said optical fiber.

39. The system of claim 38, wherein at least one surface of said optical element is a hyperbolic collimating surface.

40. A coupler comprising:

an optical source for providing an input optical signal;

a lens having a slope discontinuity for receiving the input optical signal and forming an optical signal having an annular intensity profile from the input optical signal;

an output optical fiber configured to receive the optical signal having an annular intensity profile; and

an optical axis running from said input optical fiber through said transfer lens and onto the output optical fiber, wherein the optical fiber, transfer lens, and output optical fiber are substantially optically aligned along the optical axis.

41. The coupler of claim 40, wherein the annular intensity profile comprises:

30 percent or less of the total light output within a radius of about 4.5 microns from the optical axis; and

at least 86 percent of the total light output within a radius of about 19 microns from the optical axis.

42. The coupler of claim 40, wherein at least a majority of the optical signal having an annular intensity profile is received and transmitted by the output optical fiber.

43. The coupler of claim 40, wherein the output optical fiber further comprises a first end proximate to the lens and a second end distal to the lens, the output optical fiber configured to receive the output signal having the annular intensity profile and transfer the signal to the second end such that the transferred light substantially retains the annular intensity profile at the second end.

44. A coupler comprising:

an optical source for providing an input optical signal;

a lens having a slope discontinuity for focusing the input optical signal into an optical signal having an annular intensity profile; and

an output optical fiber configured to receive within a first end of the output optical fiber and transmit the optical signal having an annular intensity profile, wherein the optical signal received within the first end of the output optical fiber substantially retains its annular intensity profile during transmission by the output optical fiber to a second end of the output optical fiber.

45. The coupler of claim 44, wherein the annular intensity profile comprises:

30 percent or less of the total light output within a radius of about 4.5 microns from an optical axis of the output optical fiber; and

at least 86 percent of the total light output within a radius of about 19 microns from the optical axis of the output optical fiber.

46. The system of claim 44, wherein the lens is a defocused well-corrected optic relative to a first end of the output optical fiber.

47. The system of claim 44, wherein the lens and the output optical fiber are adjusted in position relative to each other so as to emphasize the annular distribution of the signal transferred by the output optical fiber.