Distribution optical fiber tap

• US 4,889,403 A
• Filed: 12/23/1987
• Issued: 12/26/1989
• Est. Priority Date: 11/02/1987
• Status: Expired due to Fees

• Current Assignee: Raychem Corporation (TE Connectivity Limited)
• Original Assignee: Raychem Corporation (TE Connectivity Limited)
• Inventors: Call, Tom, Rodhe, Peder, Shen, Nelson M., Campbell, Bruce D., Zucker, Joseph
• Primary Examiner(s): Lee, John D.
• Application Number:
  US07/137,317
• Time in Patent Office: 734 Days
• Field of Search: 350/96.15, 350/96.16, 350/96.18, 350/96.20, 350/96.29, 250/227
• US Class Current: 385/32
• CPC Class Codes: G02B 6/4201 Packages, e.g. shape, construction, internal or external details
• CPC Class Codes: G02B 6/4285 Optical modules characterised by a connectorised pigtail
• CPC Class Codes: G02B 6/4286 Optical modules with optical power monitoring
• CPC Class Codes: G02B 6/4289 by inducing bending, microbending or macrobending, to the light guide

Abstract

An optical fiber read or write tap includes a substrate having a substantially flat upper surface on which two separated grooves are formed, a light element being disposed in the second groove so as to be capable of coupling light with a bent portion of an optical fiber disposed in the first groove.

Claims

1. An apparatus, comprising:

a first optical fiber tap, the first tap including;

a substrate having a substantially flat upper surface on which a curved first grooved is formed and on which a second groove is formed, a first end of the second groove being displaced from and confronting the first groove;

an optical fiber including a core surrounded by a cladding surrounded by a coating disposed at least partially within the first groove, a width of the first groove being substantially greater than a cladding diameter and such that a bend profile of the coating is maintained substantially constant;

means for collecting light radiating from a bent portion of the optical fiber which passes through the fiber coating and into the substrate from the first groove, the light collecting means including a light collection element disposed within the second groove so that a light collection end surface thereof is adjacent the first end of the second groove;

a bend radius of an intermediate portion of the optical fiber in the first groove being between 4 and 11 millimeters and its sector angle being greater than 9° and

less than 35°

.

2. The apparatus of claim 1, a radius of curvature and sector angle over which an intermediate portion of the optical fiber is bent within the first groove being such that a total signal loss induced by the first tap to a signal in the fiber is less than 0.7 dB, the sector angle being between 9°

and 28°

.

3. The apparatus of claim 1, the light collecting means including means for reducing a spot size of the radiating light to a cross-sectional area less than a circle having a diameter of 500 um.

4. The apparatus of claim 3, the diameter being smaller than 100 um.

5. The apparatus of claim 3, the light collection element including a lens disposed so as to extend from the first end of the second groove, and a pigtail optical fiber having a front end displaced from a back end of the lens at a focal point thereof.

6. The apparatus of claim 5, the pigtail optical fiber comprising a step index optical fiber or graded index fiber.

7. The apparatus of claim 3, further comprising a top disposed over the substrate and having means for securing the optical fiber within the first groove when disposed over the substrate.

8. The apparatus of claim 7, the first groove extending between opposite edges of the substrate.

9. The apparatus of claim 1, the optical fiber comprising a single mode fiber.

10. The apparatus of claim 1, the optical fiber comprising a multimode fiber.

11. The apparatus of claim 1, the coating at the intermediate bent portion of the optical fiber having an index of refraction throughout its thickness which is higher than an index of refraction of the cladding.

12. The apparatus of claim 1, further comprising:

a light transmitter connected to a first end of the optical fiber; and

a plurality of N optical fiber taps similar in construction to the first optical fiber tap, the plurality of optical fiber taps being disposed on the optical fiber in series so as to form a read bus, N being an integer and being greater than 3.

13. The apparatus of claim 1, the first tap further comprising a resiliently deformable gel disposed in the first groove and in intimate contact with the coating of the intermediate bent portion of the optical fiber so as to function as an optical coupler.

14. The apparatus of claim 1, the light collection element comprising a pigtail optical fiber disposed so that its front end is adjacent the first end of the second groove, the pigtail optical fiber having a core less than 100 microns.

15. The apparatus of claim 1, the sector angle being between 9°

and 28°

.

16. The apparatus of claim 15, further comprising:

a light receiver connected to an end of the optical fiber; and

a plurality of N optical fiber taps similar in construction to the first optical fiber tap, the plurality of optical fiber taps being disposed on the optical fiber in series so as to form a write bus, N being an integer greater than 3.

17. An apparatus, comprising:

a first optical fiber tap, the first tap including;

a substrate having a substantially flat upper surface on which a curved first groove is formed and on which a second groove is formed, a first end of the second groove being displaced from and confronting the first groove;

an optical fiber including a core surrounded by a cladding surrounded by a coating disposed at least partially within the first groove, a width of the first groove being substantially greater than a cladding diameter and such that a bend profile of the coating is maintained substantially constant;

means for generating light disposed within the second groove;

means for focusing light generated by the generating means, the focusing means being disposed in the second groove;

a bend radius of an intermediate portion of the optical fiber in the first groove being between 4 and 11 millimeters and its sector angle being greater than 9° and

less than 35°

.