Ex Parte Lo et al

Board of Patent Appeals and Interferences

Feb 23, 2009

10659958 (B.P.A.I. Feb. 23, 2009)

UNITED STATES PATENT AND TRADEMARK OFFICE
_________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________

Ex parte JIANN-CHANG LO,
ANDREW DAIBER, MARK S. RICE,
and RAJESH K. BATRA
__________

Appeal 2009-0310
Application 10/659,958
Technology Center 2800
___________

Decided:1 February 23, 2009
___________

Before ADRIENE LEPIANE HANLON, CHUNG K. PAK, and
CATHERINE Q. TIMM, Administrative Patent Judges.

HANLON, Administrative Patent Judge.

DECISION ON APPEAL

1 The two-month time period for filing an appeal or commencing a civil
action, as recited in 37 C.F.R. § 1.304, begins to run from the decided date
shown on this page of the decision. The time period does not run from the
Mail Date (paper delivery) or Notification Date (electronic delivery).
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A. STATEMENT OF THE CASE
This is an appeal under 35 U.S.C. § 134 from an Examiner’s decision
rejecting claims 1, 8, 15, and 22, all of the claims pending in the application.
We have jurisdiction under 35 U.S.C. § 6(b). We AFFIRM.
The following Examiner’s rejections are before us:
Claims 1 and 15 are rejected under 35 U.S.C. § 103(a) as unpatentable
over the combination of Vujkovic-Cvijin2 and Koch.3
Claims 8 and 22 are rejected under 35 U.S.C. § 103(a) as unpatentable
over the combination of Vujkovic-Cvijin, Koch, and Kuo.4
The claims on appeal are directed to a tunable laser (claims 1 and 8)
and a system for tuning an external cavity diode laser (claims 15 and 22).
Claim 1 is representative of the subject matter on appeal and reads as
follows:
1. A tunable laser, comprising:
a temperature controlled sled;
an etalon;
a multiple bandwidth mode controller comprising a high
bandwidth mode and a lower bandwidth mode,

said controller to initially drive said etalon in said
high bandwidth mode for a coarse tuning adjustment and switch
to said lower bandwidth mode to drive said temperature
controlled sled for fine tuning adjustment when an error signal
associated with a target frequency is within a threshold range.

Ans. 12, Claims Appendix.5

2 US 6,724,789 B2 issued to Vujkovic-Cvijin on April 20, 2004.
3 US 6,359,915 B1 issued to Koch et al. on March 19, 2002.
4 US 6,222,861 B1 issued to Kuo et al. on April 24, 2001.
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B. ISSUES
(1) Have the Appellants shown that the Examiner reversibly erred
in concluding that the combined teachings of Vujkovic-Cvijin and Koch
would have suggested using an etalon for coarse tuning adjustment as recited
in claim 1?
(2) Have the Appellants shown that the Examiner reversibly erred
in concluding that the combined teachings of Vujkovic-Cvijin, Koch, and
Kuo would have rendered obvious the subject matter of claims 8 and 22?
C. FINDINGS OF FACT
The following findings of fact are supported by a preponderance of
the evidence. Additional findings of fact as necessary appear in the Analysis
portion of the opinion.
1. Appellants’ Specification
The Appellants describe etalons and their operation in the disclosed
invention as follows:
Generally, etalons are employed in laser cavities to
provide filtering functions. They function as Fabry-Perot
resonators. The result of passing an optical beam through an
etalon produces a set of transmission peaks (also called
passbands) in the laser output. The spacing of the transmission
peaks (in frequency, also known as the free spectral range) is
dependent on the distance between the two faces of the etalon,
e.g., faces 516 and 518 for filter F1, and faces 520 and 522 for
filter F2. As the temperatures of the etalons change, the etalon
material is caused to expand or contract, thus causing the
distance between the faces to change. This effectively changes
the optical path length of the etalons, which may be employed
to shift the transmission peaks.

* * * * *

5 Appeal Brief dated April 23, 2007.
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In one embodiment, one of the filters, known as a “grid
generator,” is configured to have a free spectral range
corresponding to a communications channel grid, such as the
ITU wavelength grid, and the peaks are aligned with ITU
channel frequencies. This wavelength grid remains
substantially fixed by maintaining the temperature of the
corresponding grid generator etalon at a predetermined
temperature. At the same time, the temperature of the other
etalon, known as the channel selector, is adjusted so as to shift
its transmission peaks relative to those of the grid generator.
By shifting the transmission peaks of the filters in this manner,
transmission peaks corresponding to channel frequencies may
be aligned, thereby producing a cavity lasing mode
corresponding to the selected channel frequency.

Spec., paras. [0035], [0036].
2. Vujkovic-Cvijin
Vujkovic-Cvijin discloses a multiple channel fiberoptic light source,
particularly for use in dense wavelength division multiplexed (DWDM)
systems. Vujkovic-Cvijin 1:14-17.
Vujkovic-Cvijin Figure 10A is a block diagram schematically
illustrating control loops included for a single channel of the fiberoptic
source in the DWDM system. Vujkovic-Cvijin 5:52-54.
Figure 10A is reproduced below:
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Vujkovic-Cvijin Figure 10A depicts control loops
for a single channel of a fiberoptic source.

According to Vujkovic-Cvijin:
Preferably, laser tuning is accomplished using at least
two control loops. The first control loop may selectively shift
the frequency grid as a unit. This may be effected, for example,
by controlling a temperature of the etalon to which lasers are
referenced. The second loop sequentially locks each of the
lasers to a particular point on the frequency grid or comb.

Vujkovic-Cvijin 9:1-6.
Referring to Figures 10, 10A, and 11, Vujkovic-Cvijin explains the
operation of the electronic control system as follows:
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Two photodiodes are used as input sensors for each laser. One
photodiode 64 is used to identify the reference frequency via
gas absorption, and one photodiode 80 for alignment of the
frequency of the laser with the etalon transmission grid. Hence,
the electronic control circuit can adjust the laser frequency to
any selected channel within a DWDM communication
system.

Vujkovic-Cvijin 11:5-11.

Vujkovic-Cvijin continues:

For the etalon plate (or other frequency grid generator),
the center (or other selected) frequency may be adjusted and
stabilized by etalon feedback control 156 using the dedicated
etalon heater thermally coupled to the etalon plate. A dedicated
thermistor is used to bring the temperature of the etalon within
the range desired (coarse tuning). . . . Once again, for both the
laser and etalon, the thermistor, heaters, and other thermal
management components may be used to adjust the gross
desired frequency range. Fine tuning and fast feedback-driving
stabilization may be accomplished with reference to the
photodiode outputs.

Vujkovic-Cvijin 11:26-41.
3. Koch
Koch discloses a Distributed Bragg Reflector laser that allows for
both a coarse tuning through mode selection, by adjusting the index of the
Bragg region, and fine tuning, by adjusting the temperature of the whole
laser. Koch 2:54-59.
D. PRINCIPLES OF LAW
A claimed invention is not patentable if the subject matter of the
invention would have been obvious to a person having ordinary skill in the
art at the time the invention was made. 35 U.S.C. § 103(a); KSR Int’l Co. v.
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Teleflex Inc., 127 S. Ct. 1727, 1734 (2007); Graham v. John Deere Co. of
Kansas City, 383 U.S. 1, 13 (1966).
The test for obviousness is not that the claimed invention must be
expressly suggested in any one or all of the references. Rather, the test is
what the combined teachings of the references would have suggested to one
of ordinary skill in the art. In re Keller, 642 F.2d 413, 425 (CCPA 1981).
A person of ordinary skill is not an automaton but is a person of
ordinary creativity. KSR, 127 S. Ct. at 1742. One of ordinary skill in the art
is presumed to have skills apart from what the prior art references expressly
disclose. In re Sovish, 769 F.2d 738, 742 (Fed. Cir. 1985).
E. ANALYSIS
1. Issue (1)6
The Examiner found that Vujkovic-Cvijin discloses a tunable laser
comprising a temperature controlled sled 154, an etalon 78, and a multiple
bandwidth mode controller comprising a high bandwidth mode and a lower
bandwidth mode. Ans. 3, 47; Vujkovic-Cvijin Figures 10 and 10A.
The Examiner found that Vujkovic-Cvijin does not disclose that the
controller drives the etalon in the high bandwidth mode for a coarse tuning
adjustment or drives the temperature controlled sled in the lower bandwidth
mode for fine tuning adjustment. Ans. 3.
However, the Examiner found that Koch discloses a tunable laser that
is mode locked by coarse tuning a filter (e.g., a Bragg region) and fine tuned
by adjusting the temperature of the laser. Ans. 3; Koch 2:54-63.

6 The Appellants do not argue the patentability of claim 15 separately from
the patentability of claim 1. See 37 C.F.R. § 41.37(c)(1)(vii) (2007).
7 Examiner’s Answer dated July 5, 2007.
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The Examiner concluded that it would have been obvious to one of
ordinary skill in the art to incorporate the teachings of Koch into the device
of Vujkovic-Cvijin by driving the mode controller in the coarse mode (by
adjusting the etalon) and fine tuning (by controlling the temperature) for at
least the purpose of mode locking the laser to a desired wavelength. Ans. 3.
The Appellants do not point to any error in the Examiner’s findings.
Rather, the Appellants argue that the Examiner improperly combined
Vujkovic-Cvijin and Koch. In particular, the Appellants argue that
Vujkovic-Cvijin controls coarse tuning with temperature in contrast to the
claimed invention which controls coarse tuning with an etalon. The
Appellants argue that even if one were to combine the references as
proposed by the Examiner, the multimode controller of Vujkovic-Cvijin
would still use temperature for coarse adjustments “as this is what is clearly
taught.” Br. 8.
The Appellants’ argument is not persuasive of reversible error. In the
§103(a) rejection before us, the Examiner relied on Koch to establish that it
was known in the art to use a filter for coarse tuning adjustments. Keller,
642 F.2d at 425. The record before us establishes that an etalon, as disclosed
in Vujkovic-Cvijin, provides filtering functions and is adjustable in response
to a change in temperature. See Spec., paras. [0035], [0036]; Vujkovic-
Cvijin 11:5-11, 26-41. Thus, the Examiner had a reasonable basis for
finding that the combined teachings of Vujkovic-Cvijin and Koch would
have suggested using a filter, such as a temperature controlled etalon, to
control the coarse tuning adjustments in the tunable laser of Vujkovic-
Cvijin. The Appellants have failed to direct us to any evidence to the
contrary.
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In sum, the Appellants have not shown that the Examiner reversibly
erred in concluding that the combined teachings of Vujkovic-Cvijin and
Koch would have suggested using an etalon for coarse tuning adjustment as
recited in claim 1.
2. Issue (2)
The Appellants do not point to any error in the Examiner’s findings of
fact or conclusion of obviousness as to claims 8 and 22. Rather, the
Appellants argue that Kuo fails to overcome the deficiencies of Vujkovic-
Cvijin and Koch in the rejection of claim 1. Br. 9-10.
For the reasons set forth above, the combined teachings of Vujkovic-
Cvijin and Koch would have rendered obvious the subject matter of claim 1.
Therefore, there are no deficiencies in Vujkovic-Cvijin or Koch that must be
overcome by Kuo in the rejection of claim 1.
F. DECISION
The decision of the Examiner is affirmed.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a) (2008).

AFFIRMED

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