  United States Court of Appeals
      for the Federal Circuit
               ______________________

              CISCO SYSTEMS, INC.,
                    Appellant

                          v.

             CIRREX SYSTEMS, LLC,
                  Cross-Appellant
              ______________________

                2016-1143, 2016-1144
               ______________________

    Appeals from the United States Patent and Trade-
mark Office, Patent Trial and Appeal Board in No.
95/001,175.
                ______________________

               Decided: May 10, 2017
               ______________________

   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.
2                         CISCO SYS., INC.   v. CIRREX SYS., LLC



CHEN, Circuit Judge.
    This case arises from Cisco Systems, Inc.’s (Cisco) re-
quest 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 de-
scription 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.
                       BACKGROUND
    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


    1   Of the original claims, claims 21–25 were amend-
ed and claim 32 was canceled. J.A. 3. Of the added
claims, claims 42, 77, 79, 88, and 123 were canceled,
claims 56, 57, 76, 102, and 103 were found patentable by
the Examiner, and claims 1–31, 33–41, 43–55, 58–75, 78,
80–87, 89–101, 104–122, and 124 were rejected on various
grounds by the Examiner. J.A. 3–4.
CISCO SYS., INC.   v. CIRREX SYS., LLC                         3



logical operation to be performed selectively on a particu-
lar 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 infor-
mation 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 infor-
mation 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 as-
sembly that uses a planar lightguide circuit (PLC). Id.
col. 1 ll. 14–17, 20–24, col. 2 l. 65–col. 3 l. 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 “sepa-
rate[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 divert-
ing elements (which can divert or introduce a light beam
of a specific wavelength). Id. col. 4 ll. 10–60, col. 14 l. 58–
col. 15 l. 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-
4                          CISCO SYS., INC.   v. CIRREX SYS., LLC



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 multi-
plexed 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′.
CISCO SYS., INC.   v. CIRREX SYS., LLC                  5




Id. fig.10 (as annotated by Cisco). As shown in Figure 10,
the diverting element 1000 is a double-sided mirror. Id.
6                          CISCO SYS., INC.   v. CIRREX SYS., LLC



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 λ3 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 infor-
mation being transmitted along each individual wave-
length 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:




’082 patent fig.7. Figure 7 shows an exemplary embodi-
ment of PLC 210E containing a four-channel drop-add.
The bottom left-hand corner shows an optical beam input
with optical energy of wavelengths λ1–λn introduced into
CISCO SYS., INC.   v. CIRREX SYS., LLC                    7



PLC 210E. Id. col. 13 ll. 22–23. Individual light wave-
lengths λ1–λ4 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 succes-
sively filtered out of the optical beam, with each wave-
length 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 sepa-
rated 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 sig-
nals 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 wave-
lengths 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 amplifi-
cation or attenuation material (1300) to increase or de-


    2   The filters located on top of PLC 210E contain
special materials that allow certain wavelengths of light
to pass through while other wavelengths of light reflect
back into the PLC, thereby achieving the zig-zag pattern
in the PLC. ’082 patent col. 10 ll. 1–53.
8                          CISCO SYS., INC.   v. CIRREX SYS., LLC



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.




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 trans-
mission 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
CISCO SYS., INC.   v. CIRREX SYS., LLC                       9



“each channel” outside the PLC can be used to (1) equalize
the intensities of light across all channels, or (2) “discrete-
ly attenuate” individual channels outside the PLC, with-
out 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 wave-
length of light being amplified, and discrete attenuation
can counter this variation in amplification. Id. col. 14 l.
59–col. 15 l. 5.
    The ’082 specification further makes clear that “dis-
crete attenuation” is distinct from “collective attenuation.”
    In the assembly illustrated in FIG. 13, the chan-
    nels operating at wavelengths lambda one (λ1)
    through lambda four (λ4) 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 illus-
    trated 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 l. 64–col. 15 l. 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 ap-
proach, 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
10                           CISCO SYS., INC.   v. CIRREX SYS., LLC



architectural assembly, including inside the zig-zag path
of PLC 210E, but it does not disclose how placing attenua-
tion material inside PLC 210E would result in the equal-
izing of the intensities of different wavelengths of light or
the discrete attenuation of different wavelengths of light
inside the PLC. Id. col. 15 ll. 22–24.
    Turning to the claims, the parties separated the
claims into three different groups: the equalization
claims, the discrete attenuation claims, and the diverting
element claims. All three groups contain claims that
depend from claim 1, reproduced below:
     1. A cross-connect waveguide system comprising:
     a planar lightguide circuit having one or more op-
     tical paths;
     a plurality of optical waveguides coupled to said
     planar lightguide circuit;
     a plurality of filtering devices for feeding light en-
     ergy into said optical paths of said planar light-
     guide circuit or receiving light energy from said
     optical paths of said planar lightguide circuit; and
     a diverting element for feeding first light energy at
     a predetermined wavelength having first infor-
     mation content away from said planar lightguide
     circuit, and for feeding second light energy at said
     predetermined wavelength having second infor-
     mation content into said planar lightguide circuit,
     wherein said diverting element is remotely config-
     urable and is controlled with optically encoded in-
     formation.
Id. col. 18 l. 61–col. 19 l. 10 (emphases added). As noted,
the optical waveguides are flexible fiber optic cables that
can feed light signals away from or into a PLC. Id. col. 2
l. 53–63. The filtering devices pass through certain
CISCO SYS., INC.   v. CIRREX SYS., LLC                   11



wavelengths of light while reflecting other wavelengths.
Id. col. 10 ll. 1–53.
    Claims 56, 76, and 102 are the equalization claims.
Claims 56 and 102 recite that “the [PLC] is operative to
equalize the intensities of light energy traveling in the
plurality of optical paths of the [PLC].” J.A. 2786, 2792.
Claim 76 recites “equalizing the intensities of light energy
while the light energy is traveling in the plurality of
optical paths of the [PLC].” J.A. 2789.
    Claims 57 and 103 are the discrete attenuation
claims. They recite that “the [PLC] further comprises a
gain flattening element to discretely attenuate light
energy traveling in the [PLC].” J.A. 2786, 2792.
    Claims 38–41, 43–47, 49–50, 58–61, 75, 84–87, 89–93,
95–96, 104–107, and 121 are the diverting element
claims. These claims recite a diverting element inside a
PLC. J.A. 26. Representative claim 46 recites that “the
diverting element is disposed along an optical path sec-
tion that spans from a first side of the [PLC] to a second
side of the [PLC] and is operative to process light travel-
ing on the optical path section.” J.A. 1558. Thus, claim
46 states that the diverting element is inside the PLC, but
it does not recite how the diverting element would divert
the light beam inside the PLC.
    Relevant, for our purposes, all of the challenged
claims recite that either equalization or discrete attenua-
tion is performed inside the PLC, or that the diverting
element is located inside the PLC.
    During reexamination, the Examiner rejected claims
1–34, which originally issued with the ’082 patent. J.A.
296, 299–306. Cirrex disputed those rejections and added
new claims 35–124. J.A. 3, 341–59. In response, the
Examiner initially rejected Cirrex’s newly presented
equalization and discrete attenuation claims for lack of
written description support, but he later withdrew those
12                        CISCO SYS., INC.   v. CIRREX SYS., LLC



rejections. J.A. 948, 1172. He maintained his rejections
of Cirrex’s new diverting element claims for lack of writ-
ten description support. J.A. 20. The Board affirmed.
J.A. 2–3, 42–43.
    Cisco appeals the patentability finding for the equali-
zation and discrete attenuation claims. Cirrex cross-
appeals the rejection of the diverting element claims. We
have jurisdiction under 28 U.S.C. § 1295(a)(4) (2012).
                       DISCUSSION
                  I. Standard of Review
    In construing the claims, the Board applies the broad-
est reasonable interpretation consistent with the specifi-
cation. Cuozzo Speed Techs., LLC v. Lee, 136 S. Ct. 2131,
2142–45 (2016). “We review intrinsic evidence and the
ultimate construction of the claim de novo.” SightSound
Techs., LLC v. Apple Inc., 809 F.3d 1307, 1316 (Fed. Cir.
2015).
    “Whether a patent claim is supported by an adequate
written description is a question of fact.” AbbVie Deutsch-
land GmbH & Co., KG v. Janssen Biotech, Inc., 759 F.3d
1285, 1297 (Fed. Cir. 2014). “We review the Board’s
conclusions of law de novo and its findings of fact for
substantial evidence.” Blue Calypso, LLC v. Groupon,
Inc., 815 F.3d 1331, 1337 (Fed. Cir. 2016). Substantial
evidence “means such relevant evidence as a reasonable
mind might accept as adequate.” Id. (internal quotation
marks omitted).
                  II. Claim Construction
    We begin with claim construction. Cisco argues that
even though the parties agreed before the Board that the
claimed “equalization” and “discrete attenuation” func-
tions must occur inside the PLC, the Board improperly
altered the construction for these limitations when it
applied the written description analysis.
CISCO SYS., INC.   v. CIRREX SYS., LLC                   13



     Equalization is recited in claims 56 and 102 as “equal-
iz[ing] the intensities of light energy traveling in the
plurality of optical paths of the [PLC].” J.A. 2786. Claim
76 similarly recites “equalizing the intensities of light
energy while the light energy is traveling in the plurality
of optical paths of the [PLC].” J.A. 2789. Consistent with
this claim language, the parties agreed before the Board
that the recited equalization must occur “while the light
energy is within the PLC.” J.A. 3386, 3561.
     Discrete attenuation is recited in claims 57 and 103,
which explain that “the [PLC] further comprises a gain
flattening element to discretely attenuate light energy
traveling in the [PLC].” J.A. 2786, 2792. Given this claim
language, the parties agreed before the Board that the
recited discrete attenuation must also occur while the
light energy is traveling inside the PLC. J.A. 3386, 3561.
     The problem for Cirrex in this case is that the ’082
specification lacks any disclosure or suggestion of how
placing attenuation material inside the PLC—which
would necessarily impact the collective wavelengths in
the PLC in the same way—would result in equalizing the
intensities of different wavelengths traveling in the PLC,
or discretely attenuating a particular wavelength in the
PLC. Cirrex, however, argued to the Board that the
intensities of the wavelengths inside the PLC could be
equalized with respect to the intensity of a wavelength
outside the PLC rather than requiring that the equaliza-
tion apply only to wavelengths inside the PLC. Cirrex’s
rather creative theory is the following: first, attenuation
material could be placed somewhere inside the PLC, and
all the wavelengths inside the PLC would travel through
the attenuation material and thus be attenuated in the
same way; and second, when one wavelength λ3 is filtered
out and soon thereafter replaced with a substitute wave-
length λ3′ coming from outside the PLC, under Cirrex’s
theory, “equalization” can be achieved if the intensity of
the collective wavelengths in the PLC had been attenuat-
14                         CISCO SYS., INC.   v. CIRREX SYS., LLC



ed to the same level of intensity as the intensity of the
newly introduced wavelength λ3′ which had not been
subject to the attenuation material. Even if this were
possible (and nothing in the specification describes such
an embodiment), Cirrex’s theory at best equalizes the
intensities of the collective wavelengths inside the PLC
with a wavelength that is outside the PLC; the equaliza-
tion claims, however, require the PLC to equalize the
intensities of different wavelengths as they are “traveling
in the plurality of optical paths of the [PLC].” J.A. 2786
(emphasis added). Cirrex’s position also appears back-
wards because it changes the intensities of the other
wavelengths λ1, λ2, and λ4 to match a specific wavelength
λ3′, without first equalizing the wavelengths λ1, λ2, and λ4
inside the PLC. Cirrex’s position assumes that the inten-
sities of the wavelengths λ1, λ2, and λ4 inside the PLC are
already equal instead of using the attenuation material to
equalize those intensities while those wavelengths are
inside the PLC.
    We thus agree with Cisco that the correct construction
for the equalization claims requires that the individual
wavelengths of light energy be equalized as to the other
wavelengths of light energy inside the PLC while those
wavelengths are inside the PLC. When the Board con-
cluded that these claims also encompassed an embodi-
ment in which light energy inside the PLC is equalized to
light energy outside the PLC, the Board incorrectly al-
tered the construction, contrary to the claims’ plain lan-
guage, as well as the parties’ agreement that the
equalization must occur while the light energy is inside
the PLC.
     Cirrex relies on the same out-of-the-box theory to
support its proposed construction of the claimed “discrete
attenuation” function.     In Cirrex’s hypothetical, the
collective wavelengths inside the PLC travel through the
attenuation material, and the newly arriving wavelength
λ3′ is added to the PLC without having undergone attenu-
CISCO SYS., INC.   v. CIRREX SYS., LLC                    15



ation. Cirrex believes that this circumstance is “discrete
attenuation” as recited in the claims because some (but
not all) of the wavelengths λ1, λ2, and λ4 are attenuated,
leaving at least one wavelength λ3′ unattenuated.
    We agree with Cisco, however, that when the attenua-
tion applies to all the light wavelengths λ1–λ4 traveling
inside the PLC, that attenuation cannot be discrete
attenuation; it is best understood to be collective attenua-
tion, even if an unattenuated light wavelength λ3′ is later
introduced into the PLC. The ’082 specification makes
clear that the discrete approach to attenuation is distinct
from the collective approach to attenuation. As the speci-
fication notes for an alternative embodiment using ampli-
fication material:
    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 illus-
    trated 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.
’082 patent col. 14 l. 64–col. 15 l. 40 (emphases added).
Thus, discrete attenuation is distinct from collective
attenuation because in the discrete approach, each wave-
length of light is separately amplified or attenuated,
whereas in the collective approach, the same amplifica-
tion or attenuation is applied to all wavelengths of light in
the same way.
    To be sure, the ’082 specification does mention placing
“attenuation material within the zigzag-depicted optical
path within the PLC 210E,” along with other possible
placement locations in the overall larger network assem-
bly. Id. col. 15 ll. 17–26. The ’082 specification does not,
however, disclose or even remotely suggest that placing
attenuation material in the PLC results in discrete atten-
16                          CISCO SYS., INC.   v. CIRREX SYS., LLC



uation. To the contrary, placing attenuation material
inside the PLC will not result in discrete attenuation
because no one disputes that the attenuation material
acts to attenuate all the wavelengths of light traveling
inside the PLC. The fact that an additional wavelength
λ3′ may be later introduced into the PLC to replace a
filtered-out wavelength λ3 does not transform a collective
attenuation into “discretely attenuat[ing] light energy
traveling in the [PLC],” as claimed. J.A. 2786 (emphasis
added).
    Thus, we correct the Board’s construction of equaliza-
tion to clarify that the individual wavelengths of light
energy inside the PLC must be equalized with respect to
other wavelengths of light energy while those wave-
lengths are traveling inside the PLC. We also correct the
Board’s construction of discrete attenuation to clarify that
discrete attenuation does not encompass using the same
attenuation element inside the PLC to attenuate all
wavelengths of light in the same way.
     III. No Written Description for the Equalization and
                 Discrete Attenuation Claims
    Turning next to the Board’s finding of patentability of
the equalization and discrete attenuation claims over
Cisco’s objection for lack of written description support,
we note first that the ’082 patent issued with original
claims 1–34, and Cirrex later added claims 35–124 during
reexamination, of which claims 56, 57, 76, 102, and 103
were found patentable. Because none of the added claims
were part of the ’082 patent’s original disclosure, Cirrex
cannot rely on them for written description support. See
Gentry Gallery, Inc. v. Berkline Corp., 134 F.3d 1473,
1479 (Fed. Cir. 1998) (The patentee’s “original disclosure
serves to limit the permissible breadth of his later-drafted
claims.”).
    The written description requirement provides that a
patentee must “clearly allow persons of ordinary skill in
CISCO SYS., INC.   v. CIRREX SYS., LLC                   17



the art to recognize that [he] invented what is claimed.”
Ariad Pharm., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351
(Fed. Cir. 2010) (en banc) (quoting Vas-Cath Inc. v. Ma-
hurkar, 935 F.2d 1555, 1563 (Fed. Cir. 1991)). “[T]he test
for sufficiency is whether the disclosure of the application
relied upon reasonably conveys to those skilled in the art
that the inventor had possession of the claimed subject
matter as of the filing date.” Id. “[T]he level of detail
required to satisfy the written description requirement
varies depending on the nature and scope of the claims
and on the complexity and predictability of the relevant
technology.” Id.
    In Gentry Gallery, Inc. v. Berkline Corp., a patentee
amended his claims to remove a limitation reciting the
placement of controls for a set of two parallel recliners on
a console between the two recliners. 134 F.3d 1473, 1479
(Fed. Cir. 1998). We reversed the district court’s conclu-
sion upholding the claims’ validity because the specifica-
tion specifically contemplated the central console as the
only location for the controls. Id. Although Gentry Gal-
lery “did not announce a new ‘essential element’ test
mandating an inquiry into what an inventor considers to
be essential to his invention and requiring that the claims
incorporate those elements,” it “applied and merely ex-
pounded upon the unremarkable proposition that a broad
claim is invalid when the entirety of the specification
clearly indicates that the invention is of a much narrower
scope.” Carnegie Mellon Univ. v. Hoffmann-La Roche
Inc., 541 F.3d 1115, 1127 (Fed. Cir. 2008) (quoting Cooper
Cameron Corp. v. Kvaerner Oilfield Prods., Inc., 291 F.3d
1317, 1323 (Fed. Cir. 2002)).
    Similarly, in PIN/NIP, Inc. v. Platte Chemical Co., we
explained that “[w]hile it is legitimate to amend claims or
add claims to a patent application purposefully to encom-
pass devices or processes of others, there must be support
for such amendments or additions in the originally filed
application.” 304 F.3d 1235, 1247 (Fed. Cir. 2002). On
18                          CISCO SYS., INC.   v. CIRREX SYS., LLC



appeal, we reversed the district court’s validity finding.
We held that the challenged claim reciting “the spaced,
sequential application of the two separate chemicals” to
certain tubers was invalid for lack of written description
support because the “originally filed application, which is
devoid of any mention or even implication that the two
chemicals can be applied in a spaced, sequential manner,
does not support the later-added claim.” Id. at 1247–48.
    Here, in asserting written description support for its
equalization and discrete attenuation claims, Cirrex
argued a modified version of Figure 10, illustrating a
possible location of the attenuation material inside the
PLC to the Board as follows:
     One simple example is illustrated below, using the
     PLC of Figure 10 of the ’082 patent to illustrate.
     In this example, a gain flattening element has
     been added to the “zig-zag” path of the PLC. Even
     if this element is not wavelength-selective, the
     gain flattening element would affect the signal
     strength of wavelengths λ1, λ2, λ3, and λ4 of the
     original input, but not the signal strength of add-
     ed wavelength λ3′. For example, the gain flatten-
     ing element may increase (or decrease) the signal
     strengths of wavelengths λ1, λ2, and λ4 (that is, a
     discrete spectral region which contains one or
     more channels) to equal the signal strength of
     added wavelength λ3′, thus equalizing the signal
     strength of each of the four wavelengths of light in
     the output signal (λ3 has been dropped from the
     output signal).
J.A. 3375.
CISCO SYS., INC.   v. CIRREX SYS., LLC                  19




’082 patent fig.10 (as modified by Cirrex).
    The Board agreed with Cirrex, finding that the
claimed equalization function encompassed the equaliza-
tion of λ1, λ2, and λ4 against λ3′, even though λ3′ was not
inside the PLC. J.A. 11. The Board also found that
placing an attenuation element inside the PLC could
support the discrete attenuation claims because even
though all the wavelengths of light λ1–λ4 inside the PLC
were collectively attenuated, the addition of an unattenu-
ated wavelength of light λ3′ from outside the PLC meant
that some wavelengths of light were attenuated and other
wavelengths were not attenuated. J.A. 12.
20                          CISCO SYS., INC.   v. CIRREX SYS., LLC



    We disagree. Under the correct claim construction, as
explained earlier, the claimed functionality of equaliza-
tion and discrete attenuation must occur inside the PLC
with respect to the wavelengths “traveling in the [PLC],”
not to wavelengths outside of the PLC. This construction
does not encompass the equalization of wavelengths λ1, λ2,
and λ4 already inside the PLC with a wavelength λ3′
coming from outside the PLC. Similarly, placing an
attenuation element inside the PLC will not result in
discrete attenuation because the attenuation element
attenuates all the wavelengths of light inside the PLC.
The fact that an additional wavelength λ3′ may be later
introduced into the PLC to replace an original wavelength
λ3 does not transform a collective attenuation into discrete
attenuation.
    We also agree with Cisco that the claims are directed
to subject matter that is indisputably missing from the
’082 specification, i.e., the claims “cover a mechanism for
acting on individual channels of light within the PLC to
discretely attenuate one of several channels” or “a mecha-
nism for acting on individual channels of light within the
PLC to make their several intensities equal.” Cisco
Opening Br. at 44 (emphases in original). The ’082 speci-
fication does not meet the quid pro quo required by the
written description requirement for the disputed claims
because demultiplexing light to manipulate separately the
intensities of individual wavelengths of light while the
light is still inside the PLC is a technically difficult solu-
tion that the ’082 specification does not solve, let alone
contemplate or suggest as a goal or desired result. Noth-
ing in the ’082 specification explains how individual
wavelengths of light are separately manipulated while
those wavelengths are still inside the PLC. Nor is there
anything in the specification that suggests that the inven-
tor contemplated that approach. To the contrary, the ’082
specification expressly describes using the PLC to sepa-
rate wavelengths of light to allow the manipulation of
CISCO SYS., INC.   v. CIRREX SYS., LLC                   21



each individual wavelength—outside the PLC—before it
is rerouted back into the PLC for remultiplexing.
     Under the correct claim construction for the equaliza-
tion and discrete attenuation claims, there is no substan-
tial evidence in the record to support the Board’s finding
that claims 56, 57, 76, 102, and 103 of the ’082 patent
have sufficient written description support. Thus, we
reverse the Board’s findings of patentability for these
claims.
    IV. Cirrex’s Cross-Appeal of the Diverting Element
                          Claims
    Cirrex cross-appeals the Board’s rejections of the di-
verting element claims for lack of written description
support, arguing that the Board cited Figures 10 and 13
of the ’082 patent and their accompanying descriptions,
but it did not consider Figure 11. Cirrex argues that
Figure 11 provides sufficient support for a diverting
element inside a PLC, as claimed.
    The Board compared Figures 10 and 13 and found
that both figures disclose a PLC and a separate element
located outside the PLC. It found that the ’082 specifica-
tion does not provide for a separate embodiment with a
diverting element inside the PLC, and therefore, the
totality of the disclosure did not establish that the inven-
tors possessed an embodiment with a diverting element
inside the PLC.
22                         CISCO SYS., INC.   v. CIRREX SYS., LLC




’082 patent figs.10–12 (as annotated by Cisco).
    Cirrex contends that Figure 11 fills in the perceived
gap in disclosure because Figure 11 shows a diverting
element in the optical path that diverts the existing
optical channel content and replaces it with new content.
Cirrex points to the ’082 specification’s explanation that
photolithographic techniques can be used to cast the
optical paths within a PLC into desired circuit patterns.
Based on these two disclosures, Cirrex contends that the
’082 patent necessarily discloses that the diverting ele-
ment is inside the PLC. Cisco responds that Figure 11
shows an “element in an optical path” of an optical circuit,
CISCO SYS., INC.   v. CIRREX SYS., LLC                    23



but it never states that this optical path is “within a
PLC.” Cisco Reply Br. at 11.
    We affirm because Figure 11 does not show a divert-
ing element inside a PLC. The PLC is shown on the left-
hand side of Figure 10, and the diverting element 1000 is
shown on the right-hand side of Figure 10, outside the
PLC. The diverting element 1000 can be set to a position
that is either “in” or “out” of the optical path of light
beams λ3 and λ3′; these positions correspond to diverting
or not diverting the light beams, in the form of a switch.
The diverting element 1000 is clearly located outside the
PLC in Figure 10, and nothing in Figure 11 suggests that
the diverting element has been moved to inside the zig-
zag area within the PLC.
     We agree that the Board reasonably read the written
description and figures in the ’082 patent to conclude that
the specification does not show a diverting element inside
a PLC. The Board properly compared Figures 10 and 13
and did not need to specifically refer to Figure 11 because
Figures 11 and 12 are blow-ups of the diverting element
of Figure 10. The Board necessarily considered Figure 11
based on its review of Figure 10 when it concluded that
“[t]he diverting element is similarly illustrated in Fig. 10,
and without an accompanying recitation that the divert-
ing element can be within the PLC.” J.A. 27.
     The fact that there are optical paths inside the PLC
(e.g., the zig-zag pattern in Figure 10) does not by itself
require Cirrex’s reading of the specification, given that
optical paths also exist outside the PLC, as shown by λ3
and λ3′ in Figure 10. It is immaterial for resolving the
written description issue in this case that photolitho-
graphic techniques can be used to cast optical paths
within a PLC because Figure 10 shows that optical paths
also exist outside the PLC, and nothing in Figure 10 or
Figure 11 shows that the diverting element is inside the
PLC. There is also no disclosure in the ’082 specification
24                        CISCO SYS., INC.   v. CIRREX SYS., LLC



of where inside the PLC the diverting element would be
placed or how that diverting element would divert the
light beams inside the PLC.
     Substantial evidence supports the Board’s finding of
lack of written description support for the diverting
element claims. Because we affirm the Board’s finding of
lack of written description support, we need not and do
not reach the Board’s alternate grounds for unpatentabil-
ity of the diverting element claims.
                      CONCLUSION
    We have considered Cirrex’s remaining arguments
and find them unpersuasive. We reverse the Board’s
finding of patentability for the equalization and discrete
attenuation claims because the ’082 patent lacks written
description support for those claims. We affirm the
Board’s rejection of the diverting element claims for lack
of written description support. We do not reach the
Board’s alternate grounds for unpatentability of the
diverting element claims.
     No costs.
 AFFIRMED-IN-PART AND REVERSED-IN-PART
