Low-profile back plane interconnection device

The low-profile back plane interconnection device includes a back plane, a daughter card, and a shroud. The back plane includes an optical fiber. The optical fiber of the back plane includes a terminal end. The terminal end of the optical fiber of the back plane has a terminal surface that is oriented at an angle relative to the longitudinal length direction of the optical fiber of the back plane. The shroud is mounted to the daughter card. The shroud includes an optical fiber, and a lens. The optical fiber of the shroud has a terminal end. The terminal end of the optical fiber of the shroud is in optical communication with the terminal end of the optical fiber of the back plane via the lens.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to back plane interconnection devices. The invention more particularly concerns a back plane interconnection device having optical fibers or waveguides so as to provide a low-profile.

2. Discussion of the Background

Optical connections between optical fibers or waveguides of an optical back plane and optical fibers or waveguides of an optical daughter card are known in the art. Two connection techniques are known in the art for connecting the optical back plane to the optical daughter card.

The first technique requires that the optical fibers or waveguides of the back plane be terminated in some manner as with a standard size ferrule. The optical fibers or waveguides of the daughter card are also terminated in some manner, such as with a standard size ferrule. Then a corresponding pair of ferrules, one from the back plane and the other from the daughter card, are brought together, and held together, so as to be in optical communication with one another, by way of an adapter housing or other similar structure.

The second technique requires that the optical fibers or waveguides of the back plane be terminated by exposing the bare terminal ends of the optical fibers or waveguides which are stripped of any insulating material. The optical fibers or waveguides of the daughter card are also terminated by exposing the bare terminal ends of the optical fibers or waveguides which are stripped of any insulating material. Then a corresponding pair of exposed ends are brought together so as to contact one another. The pair of exposed ends are then subject to high heat so as to fuse the two exposed ends to one another. The corresponding pair of optical fibers or waveguides are then in optical communication with one another.

The known techniques require a significant amount of skilled labor to perform the processes described above, and the resulting devices are large and bulky.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a back plane interconnection device that facilitates the connection of an optical back plane to an optical card.

It is a further object of the invention to provide a back plane interconnection device that is compact and has a low-profile.

In one form of the invention the device includes a back plane, and a shroud. The back plane includes an optical fiber. The optical fiber of the back plane includes a terminal end. The terminal end of the optical fiber of the back plane has a terminal surface that is oriented at an angle relative to the longitudinal length direction of the optical fiber of the back plane. The shroud includes an optical fiber. The optical fiber of the shroud has a terminal end. The terminal end of the optical fiber of the shroud is in optical communication with the terminal end of the optical fiber of the back plane.

In another form of the invention, the device contains the features described above and further includes a lens as part of the shroud. The terminal end of the optical fiber of the shroud is in optical communication with the lens. The lens is in optical communication with the terminal end of the optical fiber of the back plane.

In operation, when a first light signal is transmitted from the optical fiber of the shroud to the optical fiber of the back plane, the first light signal exits the terminal end of the optical fiber of the shroud and impinges a surface of the optical fiber of the back plane adjacent to the terminal end of the optical fiber of the back plane. Then the first light signal enters the optical fiber of the back plane and, due to total internal reflection, is reflected off of the terminal surface of the optical fiber of the back plane so that the first light signal travels along the longitudinal length direction of the optical fiber of the back plane away from the terminal end of the optical fiber of the back plane.

In operation, when a second light signal is transmitted from the optical fiber of the back plane to the optical fiber of the shroud, the second light signal travels through the optical fiber of the back plane toward the terminal end of the of the optical fiber of the back plane. Then the second light signal is, due to total internal reflection, reflected off of the terminal surface of the optical fiber of the back plane and then exits the surface of the optical fiber of the back plane adjacent to the terminal end of the optical fiber of the back plane. Then the second light signal enters the optical fiber of the shroud through the terminal end of the optical fiber of the shroud.

In operation, when a light signal is transmitted from the optical fiber of the shroud to the optical fiber of the back plane, the light signal exits the terminal end of the optical fiber of the shroud and impinges a surface of the optical fiber of the back plane adjacent to the terminal end of the optical fiber of the back plane. Then, the light signal enters the optical fiber of the back plane and, due to total internal reflection, is reflected off of the terminal surface of the optical fiber of the back plane so that the light signal travels along the longitudinal length direction of the optical fiber of the back plane away from the terminal end of the optical fiber of the back plane.

In operation, when a light signal is transmitted from the optical fiber of the back plane to the optical fiber of the shroud, the light signal travels through the optical fiber of the back plane toward the terminal end of the of the optical fiber of the back plane. The light signal is then, due to total internal reflection, reflected off of the terminal surface of the optical fiber of the back plane and then exits the surface of the optical fiber of the back plane adjacent to the terminal end of the optical fiber of the back plane. Then, the light signal enters the optical fiber of the shroud through the terminal end of the optical fiber of the shroud.

In another form of the invention, the device contains the features described above and further includes the features of the angle of the terminal end of the optical fiber of the back plane being equal to forty-five degrees, and the terminal surface of the terminal end of the optical fiber of the back plane being metallized. Also, a daughter card is included to which the shroud is mounted. Furthermore, a longitudinal length direction of the optical fiber of the shroud is substantially perpendicular to the longitudinal length direction of the optical fiber of the back plane.

Thus, the invention achieves the objectives set forth above. The invention provides a device which is compact, has a low-profile, and facilitates the optical connection of an optical back plane to an optical card.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT

Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly toFIGS. 6–10thereof, an embodiment of the present invention is a device or low-profile back plane interconnection device100which is displayed therein.FIGS. 1–5display individual components or subassemblies of components that are specifically arranged to form the device100.

FIG. 1is a front view of a back plane1. Specifically, back plane1is an optical back plane. Back plane1has waveguides or optical fibers either adhered to a surface of a substrate, or has optical fibers sandwiched between two substrates, or includes a polymer or other material molded around optical fibers. The substrates are typically made of non-conuctive or insulative materials such as mylar or other suitable polymer materials. In this application, waveguides and optical fibers can be used interchangeably, however, the term optical fibers is used in the remainders of this discussion. Additionally, the back plane1may include electrical conductors and other components.

FIG. 2is a front view of the back plane1showing three apertures2,3, and8formed in the back plane1. Apertures2and8are alignment pin apertures2,8. Alignment pin apertures2,8accept alignment pins25,26(seeFIGS. 5 and 8) so as to align various components of the device100. Aperture3is formed in the back plane1so as to expose optical fibers5,6, and7. The optical fibers5,6, and7are precisely spaced and aligned relative to one another and relative to the alignment pin apertures2,8. Methods of forming apertures in an optical back plane are well known in the art and are not further discussed.

FIG. 3is a front view of the back plane1ofFIG. 2showing optical fibers5,6, and7, which have been terminated. The terminated end of optical fiber7has a terminated surface11. The terminated surface11is cut, cleaved, or fractured at an angle which is preferably set at forty-five degrees relative to the longitudinal length direction of the optical fiber7. Furthermore, the terminated surface11can be metallized, which entails coating the terminated surface11with a metallic material. The metallized surface provides for protection and enhanced performance of the terminated surface11. Methods of terminating optical fibers and methods of metallizing surfaces of optical fibers are well known in the art and are not further discussed.

FIG. 4is an expanded, partial cross-section view of the back plane1taken along section line4—4ofFIG. 3. The optical fiber7is terminated which results in a first half12and a second half10of the optical fiber7. The terminal end of the first half12of the optical fiber7is provided with the terminal surface11. The angle at which the terminal surface11is formed relative to the longitudinal length direction of the optical fiber7is readily apparent. Optical fibers5and6are terminated in a manner similar to that of optical fiber7, however, for reasons of clarity, only optical fiber7is discussed in detail.

FIG. 5is a side view of a daughter card20and shroud21. The shroud21includes optical fiber22,23, and24, associated lenses (not shown), and alignment pins25,26. The optical fibers22,23, and24can be assembled into preexisting apertures in the shroud21, or the shroud21can be formed of two pieces which trap the optical fibers22,23, and24between the two pieces, or the shroud21can be molded around the optical fibers22,23, and24.

Likewise, the alignment pins25,26are similarly attached to the shroud21, or can be integrally molded as part of the body of the shroud21. The alignment pins25,26are precisely located relative to the optical fibers22,23, and24. Similarly, the optical fibers22,23, and24are precisely located relative to one another. The shroud is preferably made from a suitable engineering material, typically a polymer. The alignment pins, typically, are made of a metallic material. The optical fibers22,23, and24are made of optically transparent material.

The shroud21is mounted to the daughter card20. In practice, one set of ends of the optical fibers22,23, and24connect to optical or optoelectronic devices (not shown) mounted on the daughter card20. Any conventional means of mounting the shroud21to the daughter card may be employed. Three optical fiber22,23, and24are shown in this example, however, any number of optical fibers may be utilized.

FIG. 6is a top view of the device100showing the back plane1ofFIG. 3, and the daughter card20and the shroud21ofFIG. 5. The daughter card20and shroud21are mounted to the back plane1. The alignment pins25,26of the shroud21have a shape which is complimentary to the shape of the alignment pin apertures2,8of the back plane1. Thus, the alignment pins25,26, and the alignment pin apertures2,8ensure that the optical fibers22,23, and24are properly aligned with the optical fibers5,6, and7of the back plane1.

FIG. 7is a side view of the device100ofFIG. 6. The low-profile of the interconnection between the back plane1and the daughter card20is evident in such a perspective of the device100. The daughter card20/shroud21assembly can be attached to the back plane1by methods and materials known in the art.

FIG. 8is a front view of the device100. The alignment pins25,26of the shroud21are slid into the respective alignment pin apertures2,8of the back plane1so as to properly align the shroud21and daughter card20relative to the back plane1. Proper alignment of the components ensures that the optical fiber22,23,24of the shroud21will be in optical communication with the respective optical fibers5,6,7of the back plane1.

FIG. 9is an expanded, partial, cross-section view of the device100taken along section line9—9ofFIG. 8. Positioned inside a lens retaining aperture33of the shroud21is a lens32. The lens32may be further retained within the lens retaining aperture33with an adhesive material that is optically transparent and has an index of refraction that is substantially similar to an index of refraction of the material that from which the lens32is constructed. Optical fiber24is shown with an outer coat30and a substantially optically transparent material region31at a terminal end of the optical fiber24of the shroud21. The terminal end of the optical fiber24of the shroud21is in optical communication with the lens32. The terminal end of the optical fiber7of the back plane1is in optical communication with the lens32. Thus, the terminal end of the optical fiber24of the shroud21is in optical communication with a terminal end of the optical fiber7of the back plane1.

FIG. 10is an exploded, partial, cross-section view of the device100ofFIG. 9showing the path of a light signal. By way of example, in operation, when a first light signal is transmitted from the optical fiber24of the shroud21to the optical fiber7of the back plane1, the first light signal exits the terminal end of the optical fiber24of the shroud21and enters and exits the lens32. The first light signal then impinges a surface87of the optical fiber7of the back plane1adjacent to the terminal end of the optical fiber7of the back plane1. The path or ray of a first portion of the first light signal is denoted by numeral designator91. The first light signal then enters the optical fiber7of the back plane1and, due to total internal reflection, is reflected off of the terminal surface11of the optical fiber7of the back plane1so that the first light signal travels along the longitudinal length direction of the optical fiber7of the back plane1away from the terminal end of the optical fiber7of the back plane1. The path or ray of a second portion of the first light signal is denoted by numeral designator92. The lens32can be used to focus the first light signal from the terminal end of the optical fiber24of the shroud21through the cladding of the optical fiber7and onto the terminal surface11of the optical fiber7of the back plane1.

Also by way of example, in a direction of propagation opposite to the first light signal, in operation, when a second light signal is transmitted from the optical fiber7of the back plane1to the optical fiber24of the shroud21, the second light signal travels through the optical fiber7of the back plane1toward the terminal end of the of the optical fiber7of the back plane1. The path or ray of a first portion of the second light signal is denoted by numeral designator92. Then the second light signal is, due to total internal reflection, reflected off of the terminal surface11of the optical fiber7of the back plane1and then exits the surface87of the optical fiber7of the back plane1adjacent to the terminal end of the optical fiber7of the back plane1. Then the second light signal enters and exits the lens32, the second light signal then enters the optical fiber24of the shroud21through the terminal end of the optical fiber24of the shroud21. The lens32can be used to collimate the second light signal from the optical fiber7of the back plane1onto the terminal end of the optical fiber24of the shroud.