Short Reach Gap Connector

Abstract

An optical fiber connector ferrule assembly has a ferrule holder and a ferrule partially within the ferrule holder. The ferrule holder has a keying feature for setting the angular orientation of the ferrule assembly within a connector housing. The ferrule includes at least one stand-off feature on the end face of the ferrule for maintaining a controlled air gap spacing when mated to a second compatible ferrule assembly.

Claims

1. An optical fiber connector ferrule assembly comprising: a ferrule holder; and a ferrule partially within the ferrule holder and having a keying feature for setting the angular orientation said ferrule assembly within a connector housing, and further wherein the ferrule includes at least one stand-off feature on the end face of the ferrule for maintaining a controlled air gap spacing when mated to a second compatible ferrule assembly and the fibers are laser cleaved and no polishing process is required.

2. A ferrule assembly according to claim 1, where the stand-off features provide a mating gap spacing of at least 1 micron, and less than 100 microns.

3. (canceled)

4. A ferrule assembly according to claim 1, where the dimensional tolerance of bumps and offsets allow for connector losses below 2 dB per connections.

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

Description

BRIEF DESCRIPTION OF THE FIGURES

[0008] FIG. 1 shows the mating of prior art optical ferrules 100 and 111, where the said ferrules are held in alignment by means of split sleeve 200.

[0009] FIG. 2 shows a cross-sectional view of a ferrule subassembly using the ferrule of FIG. 1. Where, ferrule 100 is assembled into a ferrule holder 203, and optical fiber 101 is inserted into the concentric bore of ferrule 100.

[0010] FIG. 3 shows the critical polishing parameters of the end face of standard physical contact ferrule subassembly. Polished end face 106 of a prior art optical ferrule, must have a specified radius of curvature, fiber protrusion, and apex offset.

[0011] FIG. 4 shows the mated ferrule assemblies of FIG. 3 being biased towards each other by a pair of springs.

[0012] FIG. 5 shows how the channel reach decreases as the data rate of the optical communication increase for a MMF optical channel link. Although the optical fiber attenuation, i.e., fiber IL, of the channel decrease, the channel becomes bandwidth limited due to modal and chromatic dispersions.

[0013] FIG. 6 shows a side view of a first embodiment of a ferrule assembly according to the present invention.

[0014] FIG. 7 shows a plot of the measured IL as a function of fiber separation between two 50 micron core multimode fibers.

[0015] FIG. 8 shows a ferrule similar to the one of FIG. 6 wherein the stand-offs are rotated 45° clockwise.

DESCRIPTION OF THE INVENTION

[0016] In general, there are many fiber optic connector types defined by TIA and other industry Standards bodies for terminating OM3, OM4, OM5 and other graded-index multimode optical fiber assemblies. Therefore, here we will limit our description to the modification to a generic optical connector ferrule assembly according to the present invention. In FIG. 6, we illustrate the basic concept, where we show a ferrule 100 mounted in a ferrule holder 210.

[0017] In place of the standard cut and polish process, the end of said optical fiber protruding from the ferrule bore is laser cleaved producing a heat polished end face. The choice of stand-off design is largely determined by the laser cleaving process. Sufficient space must be maintained to allow the laser beam to cleave the fiber unobstructed and close to the ferrule end face. In this example we illustrate round bumps 202 and 203 as stand-offs.

[0018] Low cost connector ferrules for MMF can be made of a molded polymer material instead of a higher cost ceramic material, the tradeoff is precision. However, the benefit of multimode optical fibers compared to single-mode, is higher acceptable tolerances. The concept herein, is to mold one or more stand-offs on the end of said ferrule, in this example, the two bumps 202 and 203, to form spacers when mated to a seconded modified connector ferrule, thus creating a controlled gap between mating fibers. Depending on the maximum insertion loss for a given application, the gap between fibers can be adjusted by the height of the bumps. For reference, in FIG. 7, we plot the measured IL as a function of fiber separation between two 50 micron core multimode fibers. The cost and time savings are achieved by the short cleave step provided by laser cleaving process, which also heat polishes the end of protruding optical fiber close the ferrule end face.

[0019] To prevent interference between the stand-offs of each of two mating connectors, the angular orientation of the ferrule within the ferrule holder must be maintained. Here we use a flat 204 molded in the ferrule, FIG. 6. The bumps 202 and 203 are molded at an angle relative to the normal of a molded flat 204 in said ferrule to define an orientation. In this example, the bumps are rotated 45 degrees clockwise as shown in FIG. 6. When the two said ferrules are mated, the spacer bumps are positioned 90 degrees to each other 220 as illustrated in FIG. 8.

[0020] The size of the gap is determined by the size of the bumps, which can be selected based on the maximum increase in insertion loss for the giving application.

[0021] In another embodiment, a low cost connector ferrules for MMF can be made of a molded polymer material with end face angle around 8 degrees, with one or more stand-offs on the end of said ferrule. This connector reduces the optical return loss (RL) of the channels and therefore minimize potential noise penalties.

[0022] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.