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Cisco Systems, Inc. v. Cirrex Systems, LLC

United States Court of Appeals, Federal Circuit

May 10, 2017

CIRREX SYSTEMS, LLC, Cross-Appellant

         Appeals from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. 95/001, 175.

          David L. McCombs, Haynes & Boone, LLP, Dallas, TX, argued for appellant. Also represented by Debra Janece McComas; Gregory P. Huh, Julie Marie NICKOLS, Richardson, TX.

          Tarek N. Fahmi, Ascenda Law Group, PC, San Jose, CA, argued for cross-appellant.

          Before Prost, Chief Judge, Wallach and Chen, Circuit Judges.

          Chen, Circuit Judge.

         This case arises from Cisco Systems, Inc.'s (Cisco) request for inter partes reexamination before the U.S. Patent and Trademark Office of all claims of U.S. Patent No. 6, 415, 082 ('082 patent), which is owned by Cirrex Systems, Inc. (Cirrex). The '082 patent originally issued with claims 1-34, and Cirrex added claims 35-124 during reexamination and subsequently amended and canceled several original claims.[1] As relevant here, the Examiner found claims 56, 57, 76, 102, and 103 patentable and rejected claims 38-41, 43-47, 49-50, 58-61, 75, 84-87, 89-93, 95-96, 104-107, and 121 for lack of written description support. The Board affirmed. Cisco Sys., Inc. v. Graywire LLC, No. 2012-006121, 2013 WL 4782204 (P.T.A.B. Sept. 5, 2013).

         Cisco appeals the Board's patentability finding for claims 56, 57, 76, 102, and 103, and Cirrex cross-appeals the Board's rejections. Because all the claims on appeal are unpatentable for lack of written description support, we affirm, in part, and reverse, in part.


         The '082 patent is directed to the field of fiber optic communication signals. '082 patent col. 1 ll. 14-15. Fiber optic communication signals use light energy made up of multiple different wavelengths within one fiber optic cable, and it can be useful to separate an optical beam into its individual wavelength components to allow a logical operation to be performed selectively on a particular wavelength, such as adding or deleting, or changing the intensity of, the data signal carried on each specific wavelength. The "single optical beam" comprises several different wavelengths, which "can include separate information channels that are carried by a first optical beam" having one particular wavelength and "a second optical beam" having a second particular wavelength. Id. col. 1 ll. 40-50. "In other words, multiple channels of information can propagate along an optical waveguide as a single beam of light energy." Id. col. 1 ll. 27-30.

         To separate individual wavelengths from an optical beam, the '082 patent describes an optical network assembly that uses a planar lightguide circuit (PLC). Id. col. 1 ll. 14-17, 20-24, col. 2 1. 65-col. 3 1. 2, col. 4 ll. 10-36. The PLC, together with a series of filtering devices, splits the single, composite optical beam into multiple channels based on individual wavelengths. Id. col. 4 ll. 10-22. The combination PLC and filtering device "separate[s] the optical energy into at least two beams, where a first beam can contain a first information channel and a second beam can contain a second information channel." Id. col. 2 ll. 50-53. The PLC is also attached to external optical waveguides which direct the beams of individual wavelengths of light away from and back into the PLC. Id. col. 2 ll. 45-65. These external optical waveguides can include amplifiers (which increase the intensity of the light beam) and attenuators (which decrease the intensity of the light beam) to create optical systems that can perform equalization or discrete attenuation, and diverting elements (which can divert or introduce a light beam of a specific wavelength). Id. col. 4 ll. 10-60, col. 14 1. 58-col. 15 1. 40. The parties do not dispute the technical features of beam splitting, amplifying, or attenuating of light beams.

         To modify an individual wavelength of light, the '082 patent describes using a "diverting element" (1000) out- side the PLC to divert a light beam of wavelength lambda three (λ3) and replace λ3 with a different light beam of wavelength λ3', then adding λ3' back into the PLC. This "embodiment can function as an optical switch" using a "diverting element. . . that diverts a channel signal out of an optical circuit while introducing a new signal content along the same channel into the optical circuit." Id. col. 4 ll. 48-53. The "PLC and filtering device combination can form a drop or add configuration where one channel of information propagating within a multichannel or multiplexed optical beam can be either dropped from or added to the multichannel or multiplexed beam." Id. col. 4 ll. 12-16. Figure 10 shows a cross-connect feedback loop that uses a diverting element 1000 that diverts λ3 and introduces λ3'.

         (IMAGE OMITTED)

         Id. fig. 10 (as annotated by Cisco). As shown in Figure 10, the diverting element 1000 is a double-sided mirror. Id. col. 14 ll. 7-9. Figure 11 shows the diverting element in the "in" position, which diverts λ3 and introduces λ3'. Id. col. 14 ll. 47-52. Figure 12 shows the diverting element in the "out" position, in which A3 is not diverted. Id. col. 14 ll. 53-57.

         The use of the illustrated cross-connect feedback loop allows a fiber optic communication system to transmit multiple channels of information on one fiber optic cable, without sacrificing the ability to manipulate the information being transmitted along each individual wavelength of light. Id. col. 1 ll. 25-30. This maximizes efficiency because multiple wavelengths of information can be sent simultaneously rather than having to be sent in seriatim. Id. col. 1 ll. 25-30.

         The PLC (210E) itself is disclosed in more detail in Figure 7 of the '082 patent:

         (IMAGE OMITTED)

         '082 patent fig.7. Figure 7 shows an exemplary embodiment of PLC 210E containing a four-channel drop-add. The bottom left-hand corner shows an optical beam input with optical energy of wavelengths λ12 introduced into PLC 210E. Id. col. 13 ll. 22-23. Individual light wavelengths λ14 are, in succession, "dropped" by filtering out (i.e., beam splitting)[2] through the top of the PLC, and later "reintroduced" through the bottom of the PLC. Id. col. 13 ll. 24-26. As the optical beam transits within the PLC, reflecting up and down in a zig-zag fashion, the individual wavelengths-λ1, λ2, λ3, and λ4-are successively filtered out of the optical beam, with each wavelength traveling through the top of the PLC and then within its own individual optical waveguide. Because PLC 210E is part of a feedback loop circuit, Figure 7 shows how those individual wavelengths λ1, λ2, λ3, and λ4 are ultimately reintroduced through the bottom of PLC 210E.

         In this way, PLC 210E demultiplexes incoming optical energy so that individual wavelengths of light are separated and redirected outside the PLC on a channel-by-channel basis before they are returned to the PLC and remultiplexed together, after which the remultiplexed optical energy exits PLC 210E through the top right-hand corner. Id. col. 13 ll. 31-38. When Figure 7 is considered in combination with Figures 10-12 above, the data signals carried by the individual wavelengths of light that are returned to the bottom of PLC 210E can be different from the data signals carried by the individual wavelengths of light that originally exited the top of the PLC, through the use of diverting elements.

         Another way to modify an individual wavelength of light is shown in Figure 13, which discloses using amplification or attenuation material (1300) to increase or de- crease the intensity of an individual wavelength of light before it is returned to the PLC. As illustrated in Figure 13, and described in the specification, the amplification or attenuation material is located outside PLC 210E and is positioned within each individual optical waveguide path.

         (IMAGE OMITTED)

         Id. fig.13. The '082 patent explains several ways in which light energy can be amplified (such as by using a pump laser light with an optical filtering device) or attenuated (such as by using absorbing material of a certain length), and the parties do not dispute the specifics of how the amplification or attenuation is accomplished. Id. col. 15 ll. 9-43. One reason that light energy intensity for a specific wavelength should be turned up or down is to improve transmission of the beam, while reducing transmission losses, as the beam travels over long distances or between multiple destinations. Id. col. 3 ll. 2-9. This ability to apply “selective” flattening or amplification to "each channel" outside the PLC can be used to (1) equalize the intensities of light across all channels, or (2) "discretely attenuate" individual channels outside the PLC, without attenuating all the channels at the same time. Id. col. 4 ll. 56-60, col. 6 ll. 31-35, col. 15 ll. 8-10. The '082 specification does not disclose why equalization of light energy across all channels is useful, but it does disclose that amplification can vary dramatically with the wavelength of light being amplified, and discrete attenuation can counter this variation in amplification. Id. col. 14 1. 59-col. 15 1. 5.

         The '082 specification further makes clear that "discrete attenuation" is distinct from "collective attenuation."

In the assembly illustrated in FIG. 13, the channels operating at wavelengths lambda one (Ai) through lambda four (A4) are attenuated discretely by gain flattening elements 1300. . . .
The assembly illustrated in FIG. 13 supports a discrete channel approach to signal amplification which is different from the common approach of collectively amplifying the channels. In the illustrated embodiment, the elements 1300 depicted can be amplifiers that apply selective gain to each spectral region. The spectral regions may contain one or numerous channels.

Id. col. 14 1. 64-col. 15 1. 40 (emphases added). As the '082 specification explains, the discrete approach to attenuation or amplification is distinct from the collective approach because each wavelength of light is separately amplified or attenuated, whereas in the collective approach, the same amplification or attenuation is applied to all wavelengths of light in the same way. The '082 specification also briefly mentions that the attenuation material can be positioned at various places in an optical architectural assembly, including inside the zig-zag path of PLC 210E, but it does not disclose how placing attenuation material inside PLC 210E would result in the ...

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