Non-Final Rejection
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claims 1-20 are pending.
Claim Objections – Warning
Applicant is advised that should claim 4 be found allowable, claim 10 will be objected to under 37 CFR 1.75 as being a substantial duplicate thereof (or vice versa). When two claims in an application are duplicates or else are so close in content that they both cover the same thing, despite a slight difference in wording, it is proper after allowing one claim to object to the other as being a substantial duplicate of the allowed claim. See MPEP § 608.01(m). Claim 4 depends on claim 3, which depends on claim 1. Claim 10 likewise is merely a combination of the limitations of claims 1, 3, and 4, except that it is independent. The only difference seen is that claim 10 requires “the insulation layer has a central opening to expose the top surface of the mesa” while claim 3 requires “the insulation layer has a central opening to expose at least the top surface of the mesa.” The addition of “at least” does not provide any different scope, as both would require the top surface of the mesa be exposed while permitting (but not requiring) more to be exposed.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1-5, 7-11, 14-15, and 18-20 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by US 2012/0082178 (“Tamanuki”).
Regarding claim 1, Tamanuki discloses (see [0039]-[0075]; Fig. 16 and discussion thereof is most like the invention, though the other embodiments give a more complete discussion and are also relevant and may be cited) a vertical cavity surface emitting laser (VCSEL), comprising: a substrate 11; a first mirror 12 on the substrate; an active region 13 on the first mirror; and a second mirror 14, on the active region, comprising a plurality of reflector layers ([0042]), wherein a mesa 10B is defined in the second mirror, wherein the mesa tapers out from a top surface of the mesa to a periphery of the mesa (apparent in the figures), and wherein a quantity of reflector layers, of the plurality of reflector layers, in sections of the mesa decreases from a central section of the mesa, underneath the top surface, to the periphery of the mesa (also apparent in the figures; all of the reflector layers of mirror 14 are present in the center of the device, but when you get towards the bottom of the taper at the edge fewer layers are present).
Regarding claim 2, it is apparent in Fig. 16 that all of the reflector layers are present at the center of the VCSEL.
Regarding claim 3, Fig. 16 further shows an insulation layer 16B on the second mirror, wherein the insulation layer has a central opening to expose at least the top surface of the mesa. [0064] (refers to Fig. 11, but it is not discussed and will be the same in Fig. 16).
Regarding claim 4, Fig. 16 further shows a contact layer 17B on the insulation layer and over the central opening, wherein the contact layer is electrically connected to the second mirror via the central opening. [0065] (refers to method of making first embodiment, but this will be the same in Fig. 16).
Regarding claim 5, the contact layer 17B is a first contact layer, and wherein the VCSEL further comprises: a second contact layer 17A on the substrate on an opposite side of the substrate from the first mirror. [0065] (refers to method of making first embodiment, but this will be the same in Fig. 16).
Regarding claim 7, it is apparent in Fig. 16 the mesa tapers toward the active region.
Regarding claim 8, it is not stated that the region of the mesa outside of the central section of the mesa is configured to filter out optical modes. However, the structure of Tamanuki is the same as the claimed invention, with a tapered upper mirror of the VCSEL having fewer layers at the edge than in the center. Applicant explains that this is what causes the mode filtering. See [0025]. This claimed function is therefore deemed inherent. MPEP 2112.02.
Regarding claim 9, the mesa has a shape of a conical frustum. [0058] (refers to method of making first embodiment, but this will be the same in Fig. 16).
Regarding claim 10, the claim is the same as claim 4 (i.e. the combination of the limitations of claims 1, 3, and 4) and therefore is rejected for the same reasons.
Regarding claim 11, it is apparent in Fig. 16 that all of the reflector layers are present at the center of the VCSEL.
Regarding claim 14, it is apparent in Fig. 16 the mesa tapers toward the active region.
Regarding claim 15, the claim is a method claim that involves “forming” all of the layers of claim 1, so those layers are shown and “formed” as in the rejection of claim 1. The claim additionally requires that the second mirror etched to define the tapered mesa. This is shown in Fig. 7, [0058] (refers to method of making first embodiment, but this will be the same in Fig. 16).
Regarding claim 18, Fig. 16 further shows an insulation layer 16B formed on the second mirror, and etching a central opening in the insulation layer to expose at least the top surface of the mesa. [0064] (refers to Fig. 11, but it is not discussed and will be the same in Fig. 16).
Regarding claim 19, Fig. 16 further shows a contact layer 17B formed on the insulation layer, wherein the contact layer is electrically connected to the second mirror via the central opening. [0065] (refers to method of making first embodiment, but this will be the same in Fig. 16).
Regarding claim 20, it is apparent in Fig. 16 that all of the reflector layers are present at the center of the VCSEL.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 6, 12, 16, and 17 are rejected under 35 U.S.C. 103 as being unpatentable over Tamanuki in view of US 5,500,868 (“Kuriahara”).
Regarding claim 6, Tamanuki does not show an isolation region surrounding a region defined underneath the mesa. Kuriahara shows a similar VCSEL with upper reflector as mesa, and shows an ion implanted isolation region surrounding a region underneath the mesa. See item 12 in any of the embodiments, even the prior art embodiments. It would have been obvious to a person of ordinary skill in the art to include such an ion implanted region as the skilled artisan would understand it provides current confinement, forcing the carriers to flow in the center under the mesa, clearly more efficient than having current flow on the outside where there is no upper reflector and thus no lasing will occur.
Regarding claim 12, Tamanuki is a top emitting VCSEL. Bottom emitting VCSELs were also well known in the art. See Kuriahara Fig. 5. It would have been obvious to a person of ordinary skill in the art that the VCSEL may be bottom emitting as a use of a known technique to improve similar devices in the same way. MPEP 2143 I.C. Base device Tamanuki is like the claimed invention but is not bottom emitting; it is known for comparable VCSELs to be bottom emitting as in Kurihara. A person of ordinary skill could apply this teaching to Tamanuki and the result would have been predictable. The skilled artisan would recognize that they need to make some changes (make top mirror higher reflective instead of bottom; make substrate of transparent materials) but such changes are readily apparent and would have been easy and predictable for the artisan to implement.
Regarding claim 16, in Tamanuki a circular mask is applied and used for etching the mirror. [0057]-[0058]. It is not said that this is photoresist as it allows for precise control of the mask shape. It is incredibly common in semiconductor fabrication that photoresist is applied as a mask for etching. For example, Kuriahara is a VCSEL with a mesa and uses photoresist in etching. See col. 23 lines 11-28. It would have been obvious to a person of ordinary skill in the art to do so as photoresist is known in the art to allow for precise control of the mask shape.
Regarding claim 17, as above it would have been obvious to a person of ordinary skill in the art to form an isolation region. Kuriahara additionally teaches that this may be formed using the same photoresist that was used for etching. Col. 23 lines 37-67. It would have been obvious to a person of ordinary skill in the art to use the same mask for ion implantation as this requires fewer steps, the mask is already there.
Claim 13 is rejected under 35 U.S.C. 103 as being unpatentable over Tamanuki in view of US 2003/0053503 (“Yang”).
Regarding claim 13, the claim requires that the periphery of the mesa is defined in the second mirror by a moat etched down in the second mirror. This is not shown in Tamanuki, as it seems everything is etched away. It is known in the art that when making a mesa in a VCSEL it may be made as a moat, i.e. etching the mesa away but leaving the periphery. See Yang Fig. 4, [0032]. It would have been obvious to a person of ordinary skill in the art as a simple substitution of a known step for another to yield predictable results. MPEP 2143 I.B. Tamanuki differs from the claim by etching fully, rather than as a moat, but a similar device with moat is shown as in Yang. A person skilled in the art could have used a moat rather than full etching and the result would have been predictable, as the final result does not seem to substantially change. The outer periphery does not substantially affect the lasing, so whether it is kept or removed does not substantially change the ultimate operation of the device, so the result is predictable.
Conclusion
Many references show VCSELs having tapered mesa upper mirrors. An entire CPC area is dedicated to such VCSELs (H01S 5/18352). A sampling are cited with this action.
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/JAMES A MENEFEE/Primary Examiner, Art Unit 2828
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