Optical coupler

• US 3,870,396 A
• Filed: 07/05/1973
• Issued: 03/11/1975
• Est. Priority Date: 07/05/1973
• Status: Expired due to Term

• Current Assignee: Frank L. Thiel, Jerome G. Racki
• Original Assignee: Frank L. Thiel, Jerome G. Racki
• Inventors: Thiel, Frank L., Racki, Jerome G.
• Primary Examiner(s): Corbin, John K.
• Application Number:
  US05/376,579
• Time in Patent Office: 614 Days
• Field of Search: 350/96R,96B,96WG,169-174,285
• US Class Current: 385/24
• CPC Class Codes: G02B 6/2817 using reflective elements to split or combine optical signals

Abstract

A coupler to be disposed between two sections of optical signal transmission line for extracting a fraction of the energy transmitted thereby and for coupling to the transmission line substantially all of an input optical signal. An optical signal from one section of transmission line partially reflects from a first optical interface, the reflected portion of the signal being extracted from the transmission line and the refracted portion being coupled by a tapered transparent rod to the remaining section of transmission line. An input optical signal is totally reflected from a second optical interface and is also coupled by the tapered rod into the remaining section of transmission line.

Claims

1. A light coupler for use in an optical communication system including first and second sections of Optical signal transmission line, said coupler comprising a first transparent member having first and second opposed, nonparallel planar surfaces and a third planar surface intersecting said second planar surface and making an acute angle therewith, a second transparent member having first and second opposed, nonparallel planar surfaces and a third planar surface intersecting said second surface and making an acute angle therewith, at least a portion of said second surface of said second member being parallel to and slightly spaced from said second surface of said first member, a first sheet of transparent material disposed between said first and second members, the refractive index of said sheet being less than those of said members, said sheet being disposed adjacent to at least a portion of said second surface of said first member and being disposed adjacent to less than the entire second surface of said second member, a layer of transparent material disposed adjacent to that portion of said second surface of said second member that is not adjacent to said first sheet, the refractive index of said layer being lower than that of said first sheet, first coupling means disposed adjacent to said first surface of said first member for coupling an optical signal from said first section of optical signal transmission line into said first member, the longitudinal axis of said first section of transmission line making an angle other than 90* with said second surface of said first member, output means for receiving that light which reflects from the interface between said first member and said first sheet, second coupling means disposed adjacent to said third surface of said first member for coupling light between said first member and said output means, input means for providing an input optical signal, third coupling means for coupling said input optical signal into said third surface of said second member at such an angle that said input optical signal is substantially totally reflected from the interface between said layer and said second member, fourth coupling means disposed adjacent to said first surface of said second member for combining said input optical signal and the unreflected portion of the optical signal from said first member and coupling the resultant optical signal into said second section of optical signal transmission line, and means for replacing said first sheet with a second sheet having a refractive index which is different from said first sheet and which is less than the refractive indices of said members.

2. A light coupler in accordance with claim 1 wherein said output means comprises an auxiliary optical signal transmission line having one end disposed adjacent to said second coupling means.

3. A light coupler in accordance with claim 1 wherein said sheet is slidably disposed between said first and second members.

4. A light coupler in accordance with claim 3 wherein said sheet comprises a plurality of sections each having a different refractive index.

5. A light coupler in accordance with claim 1 wherein the refractive index of said first member is equal to the refractive index of said second member.

6. A light coupler in accordance with claim 1 wherein said first and second members are first and second right prisms, respectively, said second planar surfaces of said first and second members constituting the large area faces of said prisms.

7. A light coupler in accordance with claim 6 wherein said prisms are 45* right prisms.

8. A light coupler in accordance with claim 7 wherein said first planar surfaces of said first and second members are perpendicular to the axes of said first and second transmission lines, respectively.

9. A light coupler in accordance with claim 1 wherein said layer is air.

10. A light coupler comprising first and second 45* right prisms of transparent material, each of said prisms having first anD third planar surfaces of substantially equal area and a second planar surface of greater area than said first and third surfaces, at least a portion of the second surface of said second prism being parallel to and slightly spaced from the second surface of said first prism, the first surfaces of said prisms being substantially parallel, a first sheet of transparent material disposed between said first and second prisms, the refractive index of said sheet being less than those of said first and second prisms, said sheet being disposed adjacent to at least a portion of the second surface of said first prism and being disposed adjacent to less than the entire second surface of said second prism, means for replacing said first sheet with a second sheet having a refractive index which is different from said first sheet and which is less than the refractive indices of said prisms, a layer of transparent material disposed adjacent to that portion of said second surface of said second prism that is not adjacent to said first sheet, the refractive index of said layer being lower than that of said first sheet, first, second and third elongated rods of transparent material, each of said rods terminating in first and second planar endfaces that are substantially perpendicular to the longitudinal axis thereof the first endface of said first rod being disposed adjacent to and substantially parallel to the first surface of said first prism, the first endface of said second rod being disposed adjacent to and substantially parallel to the third surface of said first prism, the first endface of said third rod being disposed adjacent to and substantially parallel to the third surface of said second prism, and a tapered rod of transparent material having large and small planar endfaces that are substantially perpendicular to the axis thereof, said large endface being disposed adjacent to said first surface of said second prism for gathering and combining optical signals emanating from said second prism.

11. A light coupler in accordance with claim 10 wherein said sheet is slidably disposed between said first and second members.

12. A light coupler in accordance with claim 11 wherein said first and second sheets are secured together in a side-by-side manner so that they lie in a single plane.

13. A light coupler in accordance with claim 11 wherein said second rod is tapered, the first endface of said second rod being larger than the second endface thereof.

14. A light coupler in accordance with claim 11 wherein said rods are provided with a layer of transparent cladding material disposed on the surface thereof, the refractive index of said cladding material being lower than that of said rods.

15. A light coupler in accordance with claim 11 wherein the refractive index of said first prism is equal to that of second prism.

16. A light coupler in accordance with claim 11 wherein said prisms are 45* right prisms.

17. A light coupler in accordance with claim 11 further comprising means for connecting the second endfaces of said first, second and third rods to optical signal transmission lines and means for connecting the small end-face of said tapered rod to an optical signal transmission line.