High speed optical system

• US 20040264854A1
• Filed: 06/30/2003
• Published: 12/30/2004
• Est. Priority Date: 06/30/2003
• Status: Active Grant

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Honeywell International Inc.
• Inventors: Cox, James A., Chen, Bo Su
• Granted Patent: US 6,961,489 B2
• Time in Patent Office: Days
• 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 coupler comprising:

an optical element having a first surface, a second surface, and an optical axis through the first and second surfaces; and

an optical medium having an end proximate to the second surface of said optical element;

wherein;

said optical element may convey light from the first surface through the second surface to the end of said optical medium; and

at least one surface has a slope discontinuity within a first distance from the optical axis.

2. 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 said optical fiber light; and

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

3. The system of claim 2, 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.

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

5. The system of claim 4, wherein light that may exit 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 and an encircled flux within a radius of about 19 microns at 86 percent or more of the total encircled flux.

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

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

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

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

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

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

12. The system of claim 10, wherein said VCSEL is a single mode light source.

13. An optical system comprising:

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

14. 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; and

wherein;

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

the output surface has a shape 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.

15. 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 a 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.

16. The system of claim 15, 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.

17. The system of claim 16, 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.

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

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

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

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

22. An optical system comprising:

an optical element having an axicon-like function on at least one surface of said optical element; and

an optical fiber having a first end proximate to said optical element.

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

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

25. The system of claim 24, wherein the axicon-like function may result 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.

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

27. An optical system comprising:

an optical fiber having a first end; and

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

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

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

30. The system of claim 29, wherein the axicon-like function may result 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.

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

32. 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.

33. The optical system of claim 32, wherein:

said light source is a laser; and

said optical fiber is multi-mode fiber.

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

35. The optical system of claim 33, wherein said laser is a multi-mode vertical cavity surface emitting laser.

36. The optical system of claim 33, wherein said optical element has at least one surface with a discontinuity in slope.

37. The optical system of claim 33, wherein said optical element is defocused relative to the first end of said optical fiber to a region corresponding to approximately ±

8λ

(f/)².

38. The optical system of claim 33, 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.

39. A method for conveying light signals through an optical fiber at an at least 10 gigahertz bit per second data rate, comprising:

inputting the light signals into an input surface of an optical element;

directing the light signals from an output surface of the optical element to an input face of the optical fiber; and

receiving the light signals of an output face of the optical fiber; and

wherein the optical element has at least one surface with a slope discontinuity in a vicinity of an optical axis of the optical element.

40. The method of claim 39, wherein the optical fiber is a multimode fiber.

41. The method of claim 40, further comprising positioning the output surface of the optical element and the input face of the optical fiber so as to result in a dark spot amidst the light signals about the center of the input face of the optical fiber.

42. The method of claim 40, further comprising adjusting the positions between the output surface of the optical element and the input face of the optical fiber so as to result an output of the light signals at the output face of the optical fiber having the following characteristics:

encircled flux within a radius of about 4.5 microns from a center of a core of the optical fiber, amounting to about 30 percent or less of the total encircled flux at the output face of the optical fiber; and

encircled flux within a radius of about 19 microns from the center of the core of the optical fiber, amounting to about 86 percent or more of the total encircled flux at the output face of the optical fiber.

43. The method of claim 42, wherein the light signals originate from a vertical cavity surface emitting laser.

44. A means for conveying light signals at a high rate, comprising:

means for emanating the,light signals;

means for conditioning the light signals and inputting the signals into an input face of an optical fiber; and

means for receiving the light signals from an output face of the optical fiber; and

wherein said means for conditioning applies an annular distribution of the light signals on the input face of the optical fiber.

45. The means of claim 44, wherein said means for receiving may detect the light signals at the output face of the optical fiber having:

an encircled flux at a radius up to 4.5 microns, of 30 percent or less of the total encircled flux at the output face of the optical fiber; and

an encircled flux at a radius up to 19 microns, of 86 percent or more of the total encircled flux at the output face of the optical fiber.

46. The means of claim 45, wherein the optical fiber is multimode fiber.

47. The means of claim 46, wherein said means for conditioning defocuses the light signals to a region on the input face of the optical fiber to approximately ±

8λ

(f/)².

48. The means of claim 47, wherein said means for conditioning the light signals comprises a lens having a surface with a slope discontinuity.

49. An optical system comprising:

an optical element having a first surface for receiving light and a second surface for outputting the light; and

an optical medium having a first surface for receiving the light and a second surface for outputting the light; and

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

50. The system of claim 49, wherein said optical element and said optical medium are adjusted in positions relative to each other so as to emphasize an annular distribution of the light on the first surface of said optical medium.

51. The system of claim 50, wherein at least one surface of said optical element is a hyperbolic collimating surface.