Claims
- 1. A fiber pigtail template assembly comprising:
a first silicon wafer having planar surface with a first plurality of grooves defining a first array therein, the first plurality of grooves terminating along a leading edge of the first silicon wafer and extending toward a trailing edge of the first silicon wafer; a second silicon wafer having a planar surface with a second plurality of grooves defining a second array, the second plurality of grooves terminating along a leading edge of the second silicon wafer and extending toward a trailing edge of the second silicon wafer, the planar surfaces of the first and second silicon wafers abutting with their leading edges aligned and the first and second plurality of grooves aligned to define fiber channels; and a receptacle defined by the first and second wafers with the planar surfaces in abutment to define the fiber channels, the receptacle being between the fiber channels and the trailing edges of the first and second silicon wafers.
- 2. The fiber pigtail template assembly of claim 1 where the grooves are V-shaped, the assembly further comprising:
a plurality of optical fibers each having a minor diameter leading portion and a major diameter trailing portion, the minor diameter leading portion of each fiber being received in a fiber channel, the receptacle being sized to receive the major diameter trailing portions of the plurality of fibers without causing a bending radius of the fibers sufficient to materially degrade wavelength propagation.
- 3. The fiber pigtail template assembly of claim 2 wherein the bending radius of the fibers is greater than or equal to 0.5 inch.
- 4. The fiber pigtail template assembly of claim 2 further comprising an epoxy securing the first and second wafers in abutment.
- 5. The fiber pigtail template assembly of claim 2 further comprising an epoxy potting the major diameter trailing portions within the receptacle.
- 6. The fiber pigtail template assembly of claim 5 where in the epoxy is an elastic epoxy that eliminates materially performance degrading stress on the fibers.
- 7. The fiber pigtail template assembly of claim 2 further comprising a spacer on each side of the fiber channels, the spacer being dimensioned to eliminate materially performance degrading stress on the fibers.
- 8. The fiber pigtail template assembly of claim 7 wherein the spacer comprises at least one pair of V-shaped spacing grooves formed in the planar surfaces of the first and second silicon wafers on each side of the first and second array of grooves, the spacing grooves being aligned to define at least one spacing channel on each side of the fiber channels with the planar surfaces of the first and second silicon wafers abutting with their leading edges aligned and the first and second plurality of grooves aligned to define fiber channels.
- 9. The fiber pigtail template assembly of claim 8 further comprising a length of optical fiber having a diameter substantially equal to that of the minor diameter portion of the plurality of fibers residing in each spacing channel.
- 10. The fiber pigtail template assembly of claim 2 further comprising a third silicon wafer sandwiching the second wafer between the first and third silicon wafers, the third silicon wafer cooperating with the first and second silicon wafers to define the receptacle.
- 11. The fiber pigtail template assembly of claim 2 wherein the first silicon wafer has a cavity defined between the first plurality of grooves and the trailing edge of the first silicon wafer and the second silicon wafer has a void between the second plurality of grooves and the trailing edge of the second silicon wafer, the cavity and the void cooperating to define the receptacle.
- 12. A method of making a fiber pigtail template assembly comprising:
a) providing a pair of first and second silicon wafers each having a planar surface with a plurality of corresponding grooves therein extending from a leading edge toward a trailing edge, the plurality of corresponding grooves, with the planar surfaces in abutment and the corresponding grooves aligned, defining a plurality of fiber channels, the first and second silicon wafers further cooperatively defining a receptacle between the fiber channels and the trailing edges of the first and second silicon wafers with the planar surfaces of the silicon wafers in abutment with the grooves aligned; b) providing a plurality of optical fibers each having a minor diameter leading portion and a major diameter trailing portion; c) placing the minor diameter leading portion of each optical fiber in a groove of one of the first or second silicon wafers; d) securing the minor diameter portion of each optical fiber in a fiber channel by abutting the planar surfaces of the first and second silicon wafers with the corresponding grooves aligned to define the plurality of fiber channels; and e) securing the major diameter portions of the optical fibers in the receptacle without materially degrading wavelength accuracy.
- 13. The method of making a fiber pigtail template assembly of claim 12 wherein step e) comprises placing the major diameter portions of the optical fibers in the receptacle with each optical fiber having a bending radius sufficient to not materially degrade wavelength accuracy.
- 14. The method of making a fiber pigtail template assembly of claim 13 wherein the bending radius is greater than or equal to 0.5 inch.
- 15. The method of making a fiber pigtail template assembly of claim 12 wherein step e) comprises potting the major diameter portions of the fibers in the receptacle using an epoxy elastic enough to eliminate any materially performance degrading stress on the fibers.
- 16. The method of making a fiber pigtail template assembly of claim 12 further comprising providing a spacer on each side of the fiber channels, the spacer being dimensioned to eliminate performance degrading stress on the fibers.
- 17. A fiber pigtail template assembly comprising:
a first silicon wafer having planar surface with a first plurality of V-shaped grooves defining a first array therein, the first plurality of grooves terminating along a leading edge of the first silicon wafer and extending toward a trailing edge of the first silicon wafer; a second silicon wafer having a planar surface with a second plurality of V-shaped grooves defining a second array, the second plurality of grooves terminating along a leading edge of the second silicon wafer and extending toward a trailing edge of the second silicon wafer, the planar surfaces of the first and second silicon wafers abutting with their leading edges aligned and the first and second plurality of grooves aligned to define fiber channels; a plurality of optical fibers each having a minor diameter leading portion and a major diameter trailing portion, the minor diameter leading portion of each fiber being received in a fiber channel; a receptacle defined by the first and second wafers with the planar surfaces in abutment to define the fiber channels, the receptacle being between the fiber channels and the trailing edges of the first and second silicon wafers, the receptacle being sized to receive the major diameter trailing portions of the plurality of fibers without causing a bending radius of the fibers sufficient to materially degrade wavelength accuracy; and an epoxy potting the major diameter trailing portions within the receptacle, the epoxy being suitably elastic to eliminate materially performance degrading stress on the fibers.
- 18. The fiber pigtail template assembly of claim 17 further comprising a spacer on each side of the fiber channels, the spacer being dimensioned to eliminate performance degrading stress on the minor diameter portion of the fibers.
- 19. The fiber pigtail template assembly of claim 18 wherein the spacer comprises at least one pair of V-shaped spacing grooves formed in the planar surfaces of the first and second silicon wafers on each side the first and second array of grooves, the spacing groves being aligned to define at least one spacing channel on each side of the fiber channels with the planar surfaces of the first and second silicon wafers abutting with their leading edges aligned and the first and second plurality of grooves aligned to define fiber channels and a length of optical fiber having a diameter substantially equal to that of the minor diameter portion of the plurality of fibers residing in each spacing channel.
- 20. The fiber pigtail template assembly of claim 17 further comprising a third silicon wafer sandwiching the second wafer between the first and third silicon wafers, the third silicon wafer cooperating with the first and second silicon wafers to define the receptacle.
- 21. The fiber pigtail template assembly of claim 17 wherein the first silicon wafer has a cavity defined between the first plurality of grooves and the trailing edge of the first silicon wafer and the second silicon wafer has a void between the second plurality of grooves and the trailing edge of the second silicon wafer, the cavity and the void cooperating to define the receptacle.
RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional Patent Application Serial No. 60/276,769, filed Mar. 16, 2001, entitled “Fiber Pigtail Template Assembly” which is incorporated herein in its entirety.
[0002] The present invention is directed toward optical communications, and more particularly toward a fiber pigtail template assembly that may be used, for example, in a bulk optical multiplexer/demultiplexer.
[0003] At the inception of fiber optic communications, typically a fiber was used to carry a single channel of data at a single wavelength. Dense wavelength division multiplexing (DWDM) enables multiple channels at distinct wavelengths within a given wavelength band to be sent over a single mode fiber, thus greatly expanding the volume of data that can be transmitted per optical fiber. The wavelength of each channel is selected so that channels do not interfere with each other and the transmission losses of the fiber are minimized. While typical DWDM allows up to 40 channels to be simultaneously transmitted by a fiber, there is an ongoing effort to further increase the number of channels transmitted for a given wavelength by an optical fiber.
[0004] DWDM requires two conceptually symmetric devices: a multiplexer and a demultiplexer. A multiplexer takes multiple beams or channels of light, each at a discrete wavelength and from a discrete source and combines the channels into a single multichannel or multiplexed beam. The input is typically a linear array of single channel waveguides such a linear array of optical fibers. The output is typically a single multichannel waveguide such as an optical fiber. A demultiplexer spatially separates a multiplexed beam into separate channels according to wavelength. Input is typically a single multichannel input waveguide or fiber and the output is typically a linear array of single channel waveguides such as optical fibers. Collective multiplexers and demultiplexers will be referred to as a “(de)multiplexer” herein.
[0005] U.S. patent application Ser. No. 09/634,619 entitled “Echelle Grating Dense Wavelength Division Multiplexer/Demultiplexer with Two Dimensional Single Channel Array,” filed Jul. 29, 2000, now U.S. Pat. No. 6,304,692 (the '692 patent) which is incorporated herein in its entirety, discloses one embodiment of a (de)multiplexer wherein the multichannel waveguide is an optical fiber and single channel waveguides are all optical fibers. In order to maintain alignment of the single channel and multichannel fibers necessary for coupling of light into and from the fibers, the fibers must be maintained in a precise spatial orientation. An assembly of aligned fibers is commonly referred to as a fiber pigtail array. Critical to maintaining the fibers in proper orientation is a fiber template. As disclosed in the '692 patent, one known structure for the pigtail fiber template is a pair of silicon wafers with V-grooves precisely located and etched therein maintain the fibers in a necessary select orientation. With a limited number of fibers, the structure as shown in FIGS. 4-6 of the '692 patent provides acceptable results. However, as more and more channels are loaded on a single fiber requiring the multiplexing of greater numbers of channels, more and more fibers must be incorporated into the fiber pigtail array. In addition, there is a need to minimize the size of optical components. Thus, while spacing of single channel fibers of 125 microns or more may now be an industry norm, smaller and smaller spacings (e.g. 80 or 40 microns or less) are likely to follow, further compacting the space within which multiple fibers must be accommodated. Because each fiber consists of a core, surrounding cladding and a protective coating, each of increasing diameter, space constraints are rapidly taxing the ability of conventional silicon templates to accommodate the ever growing number of fibers incorporated in the arrays. The problem is exacerbated by the fact that the fibers themselves are relatively brittle and excessive bend radiuses in the fibers (typically less than 0.5 inches in radius) can significantly degrade wavelength accuracy and lead to increased insertion losses. While the large bend radiuses could easily be accommodated if there were no space constraints, users demand compact (de)multiplexers, which dictates that the size of the fiber pigtail template assembly be maintained at a minimum. Other factors in a fiber pigtail template assembly not adequately addressed by the prior art have been found to cause stress induced birefringence, contributing to degradation of wavelength accuracy and increased polarization dependent loss. These include subjecting fibers of the assembly to unbalanced, excessive compression when the silicon wafers are epoxied together and overly rigid connection of the optical fibers to the fiber pigtail template assembly.
[0006] The present invention is directed toward overcoming one or more of the problems discussed above.
Provisional Applications (1)
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Number |
Date |
Country |
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60276769 |
Mar 2001 |
US |