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 . Claim 1-17 are pending.
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 1-9 and 16 are rejected under 35 U.S.C. 103 as being unpatentable over US 2014/0097456 (“Kawashima”).
Regarding claim 1, Kawashima discloses in Fig. 8, [0072]-[0073] (see also Figs. 4A-D and [0060]-[0064] describing the method of making, as Kawashima at times goes back and forth between using those reference numbers and the Fig. 8 numbers):
1. A semiconductor laser element comprising:
a nitride semiconductor layered body defining an optical waveguide, the nitride semiconductor layered body including a first n-side nitride semiconductor layer having a periodic structure of a refractive index periodically changing along a resonance direction of the optical waveguide,
Kawashimia is a nitride based DFB laser. A person skilled in the art would understand the layers form a waveguide. Layer 809c is a first n-side nitride semiconductor forms a grating via a periodic structure of periodically changing refractive index (GaN and air).
a p-side nitride semiconductor layer, an active layer disposed between the first n-side nitride semiconductor layer and the p-side nitride semiconductor layer, and including one or more well layers and one or more barrier layers,
There is p-side nitride layer 812 and active layer 804 between the p-side layer and the first n-side nitride layer 809c. The active layer is a MQW with wells and barriers.
the one or more well layers including an n-side well layer located closest to the first n-side nitride semiconductor layer among the one or more well layers, and the one or more barrier layers including an n-side barrier layer disposed between the n-side well layer and the first n-side nitride semiconductor layer, and
Kawashima says the MQW is three periods. It is not explicit that the barriers are outside of the well. A person skilled in the art understands that typically wells and barriers alternate in a MQW with barriers on the outside, and the examiner takes Official Notice of this. Therefore, there is an n-side well layer closest to the first n-side layer, and a n-side barrier between that well and the first n-side nitride layer. It would have been obvious to a person of ordinary skill in the art to include a barrier on the outside of the well as it provides carrier confinement in the wells.
a second n-side nitride semiconductor layer disposed between the first n-side nitride semiconductor layer and the active layer, wherein the second n-side nitride semiconductor layer includes In and Ga, and a thickness of the second n-side nitride semiconductor layer is greater than a thickness of the n-side barrier layer.
There is a second n-side nitride semiconductor layer 803 between the active layer 804 and the first n-side layer 809c. Layer 803 contains In and Ga and is 70 nm, greater in thickness than the 7.5 nm barriers.
Regarding claim 2, the second n-side layer 803 is made of In0.01Ga0.99N, and the first n-side layer is made of GaN and air. Adding In raises the refractive index of the second layer compared to GaN, and adding air lowers the average of the first layer. Thus, the refractive index of the second layer 803 is greater than the average refractive index of layer 809c. The thickness is also greater, 70 nm vs 50 nm.
Regarding claim 3, this example does not give the material of the barrier layer. Example 3 is also a laser and uses many of the same materials, including the same well layer and layer 103, and uses a GaN barrier. It would have been obvious to a person of ordinary skill in the art to use a GaN barrier as this is shown to be a reasonable barrier layer usable with those materials of the well and surrounding layers. See also MPEP 2144.07 (selecting known material for its intended use is generally obvious). In that case the refractive index of the second n-side nitride semiconductor layer is greater than a refractive index of the n-side barrier layer, because the addition of In raises the index.
Regarding claims 4-5, the thickness of layer 803 in this example is given as 70 nm, not 200 nm or more as claimed. In this case the distance from the first n-side layer to the first well layer is also not greater than 300 nm. However, earlier Kawashima is discussing similar layer 103 and indicates that it may be a wide range of thicknesses, preferably more than 30 nm and less than 1000 nm. [0048]. While this is not the same embodiment, the layer has the same function, and the thickness is what helps it perform this function making a result effective variable. Selecting the claimed thicknesses is therefore no more than a routine optimization within the prior art conditions through routine experimentation. See MPEP 2144.05 II.
Regarding claim 6, the thickness of the first n-side layer is 50 nm.
Regarding claim 7, the ends of the periodic structure in a width direction perpendicular to the resonance direction are located inside the nitride semiconductor layered body.
Regarding claim 8, again the first n-side nitride semiconductor layer includes a plurality of first portions and a plurality of second portions, air and GaN, the second portions each having a refractive index greater than a refractive index of each of the first portions, and the periodic structure is formed by alternately disposing the first portions and the second portions along the resonance direction.
Regarding claim 9, the ends of either the first portions or the second portions in a width direction perpendicular to the resonance direction are located inside the nitride semiconductor layered body.
Regarding claim 16, the length of the waveguide is not given. The length of DFB lasers is very typically 1000 μm or more and the examiner takes Official Notice of that fact. A person skilled in the art would understand that cavity length affects cavity volume, affecting things like output power. It would have been obvious to a person of ordinary skill in the art to make the length as claimed to as an obvious optimization. See MPEP 2144.05 II.
Claims 10-15 and 17 are rejected under 35 U.S.C. 103 as being unpatentable over Kawashima in view of WO 2019/146321 (“Hagino”) (translation already in file).
Regarding claims 10 and 12, again Kawashima uses GaN and air to make the grating, so does not meet these claimed materials. Hagino shows a similar device, a nitride based DFB laser. Hagino further shows that the grating layer may be made of two layers with different refractive index, similar to Kawashima, that one may be AlGaN and the other may be GaN or InGaN, among other things. See page 6 of document in the file, 5th and 6th paragraphs (starting “As shown in Fig. 1B…” and “In the present embodiment, the diffraction grating 70…”). It would have been obvious to a person of ordinary skill in the art to use such materials as it is generally obvious to select known materials usable for their intended purpose. See MPEP 2144.07. In both references the grating has the same general purpose, and the main requirement is just using different refractive index materials, so using such known materials would have been obvious and predictable.
Regarding claim 11, Kawashima additionally shows an n-side cladding 811 on an opposite side of the first n-side layer from the active layer. There is not shown a third n-side nitride semiconductor layer disposed between the n-side cladding layer and the first n-side nitride semiconductor layer and having a refractive index between a refractive index of the n-side cladding layer and an average refractive index of the first n-side nitride semiconductor layer. A person skilled in the art would understand that various and multiple cladding and waveguiding layers are often included in a laser, such layers are well known and the examiner takes Official Notice of that fact. It would have been obvious to a person of ordinary skill in the art to include additional such layers, and to optimize their refractive index as compared to the other layers, to precisely control how the light is confined in the active region.
Regarding claim 13, Kawashima further discloses that there may be a fourth n-side nitride semiconductor layer disposed between the second n-side nitride semiconductor layer 803 and the first n-side nitride semiconductor layer 809c. Fig. 8 shows an unlabeled layer between 803 and 809c, and [0073] explains that a GaN layer is grown over the grating, and layer 803 is grown on this GaN layer. This fourth layer made of GaN has a refractive index between that of 803 (which has In added) and the average of layer 809c (which has air added, or in parent claim 12 has Al added).
Regarding claim 14, the thickness of the second layer 803 being greater than the fourth unlabeled layer is not described. But again, as with claim 4, Kawashima suggests that the layer 803 may have a much larger thickness. The grating layer 809c is already smaller in thickness than the layer 803, and it is apparent that the additional unlabeled layer is not intended to be very thick. In any event, a person of ordinary skill would understand that the thickness of the layers will affect the confinement and the waveguiding, therefore they may be chosen and optimized as needed through routine experimentation. See MPEP 2144.05 II.
Regarding claim 15, the width of the waveguide is not given. Hagino again shows a similar laser, and shows that a waveguide width may be 10 μm or more. See 6th page of document in file, paragraph 3, showing the width of the ridge, which corresponds to the width of the waveguide. It would have been obvious to a person of ordinary skill in the art to use such value for the waveguide width. Hagino shows it is a reasonable width for a similar laser, and a person skilled in the art would understand that the waveguide width affects the output, determining the output power and modes that propagate.
Regarding claim 17, the protective films are not shown. Hagino shows a similar laser in Fig. 1 and discloses that the end faces on each end 95r,95f of the laser may have a dielectric multilayer film thereon. Par. bridging pages 7-8 in the document in the file. It would have been obvious to a person of ordinary skill in the art to include such films as the skilled artisan would recognize that they protect the laser facets, and also that they may be used to alter the reflectivity. A person skilled in the art would understand the reflectance of a laser should be higher at the non-emitting end. The person would also choose 30% reflectivity or more to ensure that more of the light stays in the cavity, causing more light amplification (such facet reflectivities are more typically well over 90%).
Conclusion
A couple other references having similarities are cited.
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/JAMES A MENEFEE/Primary Examiner, Art Unit 2828
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