Ex Parte PartridgeDownload PDFPatent Trial and Appeal BoardSep 24, 201814814426 (P.T.A.B. Sep. 24, 2018) Copy Citation UNITED STA TES p A TENT AND TRADEMARK OFFICE APPLICATION NO. FILING DATE 14/814,426 07/30/2015 22878 7590 Agilent Technologies, Inc. Global IP Operations 5301 Stevens Creek Blvd Santa Clara, CA 95051 09/26/2018 FIRST NAMED INVENTOR Guthrie Partridge UNITED STATES DEPARTMENT OF COMMERCE United States Patent and Trademark Office Address: COMMISSIONER FOR PATENTS P.O. Box 1450 Alexandria, Virginia 22313-1450 www .uspto.gov ATTORNEY DOCKET NO. CONFIRMATION NO. 20150079-01 1024 EXAMINER HAGAN, SEAN P ART UNIT PAPER NUMBER 2828 NOTIFICATION DATE DELIVERY MODE 09/26/2018 ELECTRONIC Please find below and/or attached an Office communication concerning this application or proceeding. The time period for reply, if any, is set in the attached communication. Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the following e-mail address(es): IPOPS.LEGAL@agilent.com Agilentdocketing@cpaglobal.com PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE PATENT TRIAL AND APPEAL BOARD Ex parte GUTHRIE PARTRIDGE 1 Appeal2018---002723 Application 14/814,426 Technology Center 2800 Before BEYERL YA. FRANKLIN, JEFFREY R. SNAY, and MICHAEL G. McMANUS, Administrative Patent Judges. FRANKLIN, Administrative Patent Judge. DECISION ON APPEAL 1 Appellant identifies the real party in interest as Agilent Technologies, Inc. Appeal2018-002723 Application 14/814,426 Appellant requests our review under 35 U.S.C. § 134 of the Examiner's decision rejecting claims 1, 2, 4--7, 10, 11, and 13-15 (note: the rejection of claims 8, 9, 16, and 18 has been withdrawn in the Answer ( Ans. 2)). We have jurisdiction over the appeal under 35 U.S.C. § 6(b). STATEMENT OF THE CASE Claim 1 is illustrative of Appellant's subject matter on appeal and is set forth below: 1. An apparatus comprising: a gain chip assembly comprising first and second gain chips that are coupled optically such that light travels serially between said first gain chip and said second gain chip, each gain chip being electrically biased, said electrical bias of said first gain chip being independent of said electrical bias of said second gain chip; an external cavity having a tunable wavelength selective filter that selectively passes light in a pass band that is changed in response to a control signal, light in said external cavity passing through said gain chip assembly; and a controller that generates said control signal, and said electrical bias of each of said gain, wherein said first gain chip comprises an active layer comprising a first sub-layer having a plurality of quantum well layers characterized by a first quantum well thickness, said second gain chip comprises an active layer having second and third sub-layers, said second sub-layer comprising a plurality of quantum well layers characterized by a second quantum well 2 Appeal2018-002723 Application 14/814,426 thickness, and said third sub-layer comprising a plurality of quantum well layers characterized by a third quantum well thickness, said second and third sub-layers being connected in series to said electrical bias of said second gain chip, said first, second, and third quantum well thicknesses being different from one another, and wherein said first, second and third quantum well thicknesses are chosen such that only one of said first, second, and third sub-layers supports lasing at any given electrical biases of said first and second gain chips, whereas a single gain chip having an active layer with said three sublayers would support simultaneous lasing by two of said first, second, and third sub-layers. The Examiner relies on the following prior art references as evidence of unpatentability: Miller us 4,680,769 Jul. 14, 1987 Patel et al. US 2008/0159341 Al Jul. 3, 2008 Berger us 6,091,751 Jul. 18, 2000 Hong et al. us 6,104,739 Aug. 15, 2000 Lasher us 3,427,563 Feb. 11, 1969 Hirata et al. US 6,738,398 B2 May 18, 2004 THE REJECTIONS 3 Appeal2018-002723 Application 14/814,426 1. Claims 1 and 5 through 7 are rejected under 35 U.S.C. § 103 as being unpatentable over Miller in view of Patel, and further in view of Berger. 2. Claims 2, 4, 10, 11, and 13 through 15 are rejected under 35 U.S.C. § 103 as being unpatentable over Miller in view of Patel, in view of Berger, and further in view of Hong. ANALYSIS Upon consideration of the evidence on this record and each of the respective positions set forth in the record, we find that the preponderance of evidence on this record supports Appellant's position for the reasons provided by Appellant therein. Accordingly, we reverse each of the Examiner's rejections on appeal, and add the following for emphasis. Claim 1 requires that the apparatus have two gain chips with three different active layers, one on the first chip, and two on the second chip. The active layers on the second chip are connected in series. The active layers are constructed with quantum well thicknesses that are different. In addition, the thicknesses are chosen such that at any given bias of the first and second gain chips, only one of the active layers supports lasing. Finally, the active layers are chosen such that two of said active layers would simultaneously support lasing if all three active layers were connected in series in a single gain chip. We refer to pages 10-14 of the Final Office Action regarding the Examiner's rejection of claims 1 and 5-7. Therein, the Examiner relies upon Miller for disclosing a gain chip assembly having two gain chips that are arranged such that light passes serially through the chips. The Examiner 4 Appeal2018-002723 Application 14/814,426 finds that each chip in Miller has a single active region. The Examiner finds that the quantum well layers in the first chip have a different thickness than the quantum well layers in the second chip. The Examiner finds that Miller teaches that only one of the active layers in the two chips lases at any wavelength. The Examiner relies upon Berger for teaching a gain chip having two different quantum well layers with different thicknesses that are connected in series and biased by the same current. The Examiner relies upon Patel for teaching active layers having a plurality of sub-layers having a plurality of quantum well layers. The Examiner argues that one would have been motivated to have used the chip taught in Berger in place of the second chip taught in Miller because it would allow for reducing the number of chips in the device of Miller. Final Act. 10-14. With regard to Miller, Appellant disagrees with the Examiner's characterization of Miller. Appellant states that the layer thicknesses in Miller are chosen such that the two gain regions of the chips have overlap to form a gain curve with a broader continuous band of wavelengths. Miller, Figures 2 and 3. Appeal Br. 6. Appellant states that this is a key feature of the device of Miller. Id. Appellant states that to provide the enhanced gain in the region of the overlap, both chips must be lasing since the combined gain curve shown at 62 (shown in Figures 2 & 3) is higher than either of the two individual gain curves in the region of overlap. Id. Column 1, lines 44-54 of Miller are reproduced below: Specifically, an injection laser fabricated in accordance with the present application comprises a laser cavity having first and second active laser regions disposed in tandem therein, means for injecting current into the first and second active laser regions to provide gain distributions over wavelength regions in the two active laser regions 5 Appeal2018-002723 Application 14/814,426 which partially overlay to form a combined gain distribution over a range of wavelengths, and means for providing wavelength selective loss for radiation having a wavelength within that range. Appeal Br. 6. Hence, Appellant submits that the chips in Miller both support lasing when the output of the laser is at wavelengths in the overlapping region. We agree. With regard to Berger, Appellant argues that the laser of Berger is designed to lase at two different wavelengths at the same time. Berger, col. 2, line 57 to col. 3, line 9. Appeal B. 7. Appellant states that therefore the active layers must support lasing at two different wavelengths. Accordingly, Appellant submits that Berger does not provide the missing teachings of Miller. More specifically, Appellant submits that the Examiner has not pointed to any teaching in the references that the quantum well thicknesses of sub-layers are chosen such that only one of three sub-layers supports lasing at any given electrical bias of the first and second gain chips. Appeal Br. 7. Appellant states that the Examiner attempts to overcome this lack of teaching by arguing that the external cavities or wavelength filters associated with the gain chips limit the operation to one wavelength, and hence, the sub-layers must have this property. Appeal Br. 7. Appellant argues that the limitation relates to supporting lasing, not to lasing at a single wavelength. Appeal Br. 7. Appellant explains that the gain profile of the chips is such that two or more of the active regions would support lasing if the cavity or wavelength filter was set to some particular wavelength. Appellant states that the device of Miller presumably only lases at one wavelength at a time; however, each of the gain chips support 6 Appeal2018-002723 Application 14/814,426 lasing over a broad band of wavelengths. Appellant states that, as noted above, the fundamental principle of Miller is that the gain chips have overlapping gain profiles so that the combined gain chip has gain over the entire band spanned by the two gain chips. Appellant states that the principle is realized by having two gain chips that support lasing over the same sub-band of wavelengths and are both providing that gain over the band between the peaks of the individual gain curves. Appeal Br. 7. Appellant submits therefore that the Examiner has not pointed to any teaching that a single gain chip having an active layer with the three sub- layers would support simultaneous lasing by two of the first, second, and third sub-layers. Appeal Br. 7. In response, the Examiner argues that the limitations of claim 1 ( as well as claim 10) are satisfied if there exists a single bias at which only one of the first, second, and third sub-layers supports lasing at any given electrical biases of the first and second chips, but that if all three sub-layers were contained in a single chip, the sub-layers would support simultaneous lasing of two of the sub-layers. Ans. 5. In reply, Appellant argues that the Examiner bases this position on the assertion that the limitation could not be satisfied given the second requirement that "a single gain chip having an active layer with said three sub-layers would support simultaneous lasing by two of said first, second, and third sub-layers" if the "at any given electrical biases" requires the limitation to be true at all electrical biases. Reply Br. 1. Appellant states that the Examiner bases this argument on the assumption that there will always be a set of biases in which the two-chip embodiment of claim 1 would support lasing at two different wavelengths, since there is a bias at which the 7 Appeal2018-002723 Application 14/814,426 single chip serially connected sub-layers support lasing at two different wavelengths. Appellant states that this position rests on the assumption that the only factor that causes the stacked one chip embodiment to support lasing at two wavelengths is the bias current through the sub-layers. However, Appellant explains that, as pointed out at paragraphs [0023]-[0024] of the Specification, the situation in which two different sub-layers can support lasing at the same time arises from the serial connection between the sub-layers and changes in gain of the dominant sub- layer brought about by a reduction in the population inversion of that sub- layer when that sub-layer starts to lase. Reply Br. 2. Appellant also explains that as noted in paragraph [0031] of the Specification, the present application overcomes this problem by moving one of the sub-layers to a second chip. Reply Br. 2. Appellant asks that we consider a case in which the three different sub-layers are on one chip and there is a bias at which two of the sub-layers simultaneously support lasing. In such a case, Appellant states that by reconfiguring the laser to have two gain chips in which one of the two layers is now moved to a second chip, the layer on the second chip is no longer available to lase when the gain of the other sub-layer is reduced as the current is increased in the first chip. Id. Appellant further states that the Examiner asserts that if there is a bias at which a three sub-layer system will support lasing at two different wavelengths because two of the sub-layers support lasing when biased with the same current, then there will necessarily be a bias condition in which two of the sub-layers will support lasing if one of the problematic sub-layers is moved to a second chip. Reply Br. 2. However, Appellant submits that the Examiner does not point to any such teaching in the art; hence, Appellant 8 Appeal2018-002723 Application 14/814,426 assumes that the Examiner is arguing that it is inherent that such a bias condition exists. Appellant argues that the Examiner's argument assumes that the only factor determining when a chip supports lasing is the bias current through the chip and the band pass of the external cavity. Reply Br. 2. Appellant further states that as pointed out in paragraph [0024] of the Specification, the second sub-stack in the serially connected active layer chip supports lasing even though the external cavity is tuned to block such lasing because the facets of the gain chip form a second non-tunable cavity. Reply Br. 2. Appellant states that it is the combination of the gain chip and the facet cavity that causes the problem. Id. Appellant states that accordingly, if the second gain chip does not have significant reflection on the cavity closest to the external cavity reflector, there will not be sufficient gain to lase at wavelengths that are only compatible with the facet cavity no matter what the bias current. Reply Br. 2-3. In such a case, Appellant states that the external cavity determines which sub-layer lases. Accordingly, Appellant submits that it is not inherent that there is a bias condition in which two sub-layer sublayers simultaneously support lasing. Reply Br. 2- 3. We are persuaded by the aforementioned arguments. Because the Examiner's position is based in part on faulty or unsupported assumptions (as discussed, supra), we reverse Rejection 1. Since the additionally applied reference of Rejection 2 is not relied upon by the Examiner to cure the aforementioned deficiencies, we also reverse Rejection 2. 9 Appeal2018-002723 Application 14/814,426 Each rejection is reversed. DECISION ORDER REVERSED 10 Copy with citationCopy as parenthetical citation