Optical waveguides – With optical coupler – Switch
Reexamination Certificate
2000-04-14
2003-04-29
Abrams, Neil (Department: 2839)
Optical waveguides
With optical coupler
Switch
Reexamination Certificate
active
06556740
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fiber optic cross connects, and more particularly to the packaging for fiber optic cross connects.
BACKGROUND OF THE INVENTION
The use of optical cross connect (OXC) switching systems are well known-in the art for directing a light beam from one optical port in an optical transmission system to another optical port. In a typical OXC, a plurality of input optical fibers, or ports, carry light beams into the OXC. The OXC then directs, or switches, the light beams to their respective plurality of output ports. Many conventional OXCs perform the switching utilizing micromirrors, which are micro-machined onto a chip. The micromirrors are used to reflect a light beam from an input port to a particular output port. In this specification, the words “input” and “output” are used to indicate a direction of travel for a light beam into and out of, respectively, a switch. In reality, the input and output ports can be used simultaneously for input and output, as is the case in bi-directional data transfer.
High port count switches utilizing micromirrors are of high demand in the industry. Such switches require a tight packing density of the micromirrors onto the substrate. Some conventional switches use a digital switching matrix for N input and N output ports with an N×N array of micromirrors. This requires a total of N
2
number of micromirrors. However, this architecture becomes impractical for switch port counts greater than a few hundred.
Some conventional switches use an analog switching matrix for N input and N output ports. This requires 2*N micromirrors. In this configuration, two separate chips, or one very large chip, are necessary to accommodate port counts greater than a few hundred. However, the use of more than one chip is cumbersome as they need to be aligned to each other within the package of the switch. This adds complexity to the assembly of the package and increases package size. Also, with a hundred or more micromirrors on a single chip, or one half of a two-chip OXC, device yield is compromised due to the large number of possible failure points. Additionally, the optical components of the OXC are typically hermetically sealed. Such hermetic sealing of the optical components requires additional complex steps in the manufacturing process, such as metallization of the fibers or optical component attached to the fibers.
Accordingly, there exists a need for an improved OXC package which reduces the size of the device. The present invention addresses such a need.
SUMMARY OF THE INVENTION
The present invention provides an improved fiber optic cross connect (OXC) package which reduces the size of the device. The OXC includes a chip, the chip including a plurality of input micromirrors and a plurality of output micromirrors; and a reflector optically coupled to the plurality of input micromirrors and the plurality of output micromirrors. The OXC package in accordance with the present invention folds the light beam during scanning. In the preferred embodiment, the OXC package comprises input and output micromirrors on a single chip. A reflector is placed above both the input and output micromirrors for folding the light beam as it travels between an input micromirror and an output micromirror. In the preferred embodiment, the distance from the input/output micromirror to the reflector is approximately one-half of the Rayleigh Length of the light beam. With the folding of the light beam in this manner, the input and output micromirrors may be placed in close proximity to each other, resulting in a smaller device.
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Lin, L.Y. et al., “Free-Space Micromachined Optical Switches with Submillisecond Switching Time for Large-Scale Optical Crossconnects,” IEEE Apr. 1998, vol. 10, No. 4, pp. 525-527.
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Bhattarai Amal Ranjan
Hagelin Paul Merritt
Abrams Neil
NanoGear
Sawyer Law Group LLP
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