DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 07/02/2026 has been entered.
Response to Arguments
Applicant’s arguments, see pages 10 and 11, filed 07/02/2026, with respect to the rejection(s) of claim(s) 1, 11, and 13 under 35 U.S.C. § 103 have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of the newly found reference to Witzens et al. (US 9036953 B2).
In response to applicant's argument that the references fail to show certain features of the invention, it is noted that the features upon which applicant relies (i.e., “the thickness of the first waveguide layer is functionally tied to the depletion layers formed in the PN junction regions and to the second (SiGe) rib waveguide layer”) are not recited in the rejected claim(s). Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993).
In response to applicant's argument that the references fail to show certain features of the invention, it is noted that the features upon which applicant relies (i.e., “the claimed thickness configuration causes changes in concentrations of electrons and holes in the rib waveguide to occur in the second (SiGe) rib waveguide layer, thereby increasing the effective refractive index change amount of the optical phase shifter. This thickness configuration contributes to carrier concentration changes intensively occurring in the second (SiGe) rib waveguide layer, thereby increasing the effective refractive index change amount and improving optical modulation efficiency”) are not recited in the rejected claim(s). Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993).
In the event where the above indicated features are recited in the claims, it is noted that the features upon which applicant relies are functional/process limitations but claim 1 is directed to an optical phase shifter, which is a product/apparatus claim. The patentability of a product depends only on the claimed structural limitations of the product and must be distinguished structurally. When the structure recited in the reference is substantially identical to that of the claims, a prima facie case of either anticipation or obviousness has been established. In re Best, 562 F.2d 1252, 1255, 195 USPQ 430, 433 (MPEP 2112.01 [R-07.2015]). The burden is on the applicant to show that the prior art device does not possess the claimed properties or is not capable of these functional characteristics. (See MPEP 2112.01).
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.
Claim(s) 1-2 and 16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Fujikata et al. (US 10146070 B2) in view of Witzens et al. (US 9036953 B2).
Regarding claim 1: Fujikata et al. discloses an optical phase shifter comprising: a slab waveguide in which a first slab region (1130) doped into a first conductivity type (p-type) and a second slab region (1132) doped into a second conductivity type (n-type) are arranged side by side to form a PN junction (fig. 11); and a rib waveguide (1110) disposed on the slab waveguide, the rib waveguide including a first rib waveguide layer (1126 or alternatively 1126 and 1128 combined) adjacent to the slab waveguide, a second rib waveguide layer (1108) stacked on the first rib waveguide layer, and a third rib waveguide layer (1122) stacked on the second rib waveguide layer, wherein one side of the first rib waveguide layer makes contact with the first slab region (1130), and an opposite side of the first rib waveguide layer makes contact with the second slab region (1132) (Note: “makes contact” not overlaps; “makes contact” at one point is also “makes contact”), wherein the first rib waveguide layer, the second rib waveguide layer, and the third rib waveguide layer are doped into the first conductivity type (fig. 11; all three layers 1126, 1108, and 1122 are p-type), wherein a depletion layer is formed between the first slab region (1130) and the second slab region (1132) and between the second slab region and the first rib waveguide layer, and, when a reverse voltage is applied to the optical phase shifter, an area of the depletion layer is increased (col. 8, lines 52-60), wherein the first rib waveguide layer (1126) and the third rib waveguide layer (1122) include silicon (Si), wherein the second rib waveguide layer (1108) includes silicon-germanium (SiGe) (fig. 11).
Fujikata et al. further discloses the optical phase shifter is configured to respond to application of a reverse voltage by (a) increasing areas of a depletion layer (col. 8, lines 44-60), and (c) changing an effective refractive index change amount (col. 2, lines 17-21 and col. 8, line 61 through col. 9, line 18), but is silent with respect to (a) increasing areas of the first depletion layer and the second depletion layer, (b) changing concentrations of electrons and holes in the rib waveguide, and (c) increasing an effective refractive index change amount. Fujikata et al. further fails to teach a thickness of the first rib waveguide layer that is adjacent to the slab waveguide is thinner than a thickness of the third rib waveguide layer that are sequentially stacked.
Witzens et al. discloses a waveguide (27) having core layers (57, 55, 61) are sequentially stacked where a thickness of the first rib waveguide layer (57) is thinner than a thickness of the third rib waveguide layer (61)(fig. 6; col. 19, lines 20-28); when a reverse voltage is applied (a) increasing areas of the first depletion layer and the second depletion layer (col. 18, lines 46-51), (b) changing concentrations of electrons and holes in the rib waveguide (col. 18, line 52 through col. 19, line 5), and (c) increasing an effective refractive index change amount (col. 18, lines 46-51).
Therefore, it would have been obvious to a person having ordinary skill in the art, before the effective filing date of the claimed invention to have Fujikata et al.’s waveguide layers’ thicknesses as taught by Witzens et al. since such modification is a matter of design choice for higher modulation performance (col. 19, lines 29-44). Further, it would have been obvious to a person having ordinary skill in the art to modify the optical phase shifter of Fujikata et al. to increase areas of depletion, change concentrations, and increase an effective refractive index change amount, in response to the application of a reverse voltage, to optimize the device’s performance by lowering transit time, reducing modulation loss, and having a higher limit to the maximum modulation frequency (col. 18, line 52 through col. 19, line 10). In addition, the limitation “the optical phase shifter is configured to…” is considered as a functional limitation. When the structure recited in the reference is substantially identical to that of the claims, a prima facie case of either anticipation or obviousness has been established. In re Best, 562 F.2d 1252, 1255, 195 USPQ 430, 433 (MPEP 2112.01 [R-07.2015]). In this case, Fujikata et al. in view of Witzens et al. discloses an optical phase shifter comprising a slab waveguide and a rib waveguide having a first, second, and third rib layers, a first and second depletion layers that are substantially identical to that of the claimed invention, therefore the claimed properties or functions are presumed to be inherent or obvious. The burden is on the applicant to show that the prior art device does not possess the claimed properties or is not capable of these functional characteristics. (See MPEP 2112.01).
Regarding claim 2: Fujikata et al./ Witzens et al. discloses the optical phase shifter of claim 1, wherein, when the reverse voltage is applied to the optical phase shifter (Fig. 11), concentrations of electrons and holes in the second rib waveguide layer (1108) establish a refractive index of the second rib waveguide layer, and a phase of light passing through the second rib waveguide layer (1108) is controlled by the refractive index (col. 2, lines 16-21).
Regarding claim 16: Fujikata et al./ Witzens et al. discloses the optical phase shifter of claim 1, wherein the one side of the first rib waveguide layer (1126 and 1128 combined) overlies the first slab region (1130), and the opposite side of the first rib waveguide layer overlies the second slab region (1132) (fig. 11).
Claim(s) 1 and 10-13 is/are rejected under 35 U.S.C. 103 as being unpatentable over Zhou et al. (US 2021/0373363 A1) in view of Witzens et al. (US 9036953 B2).
Regarding claim 1: Zhou et al. discloses an optical phase shifter comprising: a slab waveguide in which a first slab region (430) doped into a first conductivity type (p-doped) and a second slab region (440) doped into a second conductivity type (n-doped) are arranged side by side to form a PN junction; and a rib waveguide (450”) disposed on the slab waveguide, the rib waveguide including a first rib waveguide layer (434) adjacent to the slab waveguide, a second rib waveguide layer (444) stacked on the first rib waveguide layer, a third rib waveguide layer (436) stacked on the second rib waveguide layer, wherein one side of the first rib waveguide layer (434) makes contact with the first slab region (430), and an opposite side of the first rib waveguide layer (434) makes contact with the second slab region (440), wherein the first to third rib waveguide layers (434, 444, 436 within the rib region) are doped into the first conductivity type (Par. 81), wherein a first depletion layer is formed between the first slab region (430) and the second slab region (440), wherein a first depletion layer is formed between the second slab region (440) and the first rib waveguide layer (434) (a depletion layer is an inherent feature of the P-N junction where oppositely doped semiconductor materials meet), wherein the first rib waveguide layer (434) and the third rib waveguide layer (436) include silicon (Si) ([0024]), wherein the second rib waveguide layer (444) includes silicon-germanium (SiGe) ([0024]).
Zhou et al. further discloses changing concentrations of electrons and holes in the rib waveguide (figs. 15A-B; [0103]-[0105]), but is silent with respect to and wherein the optical phase shifter is configured to respond to application of a reverse voltage by (a) increasing areas of the first depletion layer and the second depletion layer, (b) changing concentrations of electrons and holes in the rib waveguide, and (c) increasing an effective refractive index change amount. Zhou et al. also fails to teach a thickness of the first rib waveguide layer that is adjacent to the slab waveguide is thinner than a thickness of the third rib waveguide layer that are sequentially stacked.
Witzens et al. discloses a waveguide (27) having core layers (57, 55, 61) are sequentially stacked where a thickness of the first rib waveguide layer (57) is thinner than a thickness of the third rib waveguide layer (61) (fig. 6; col. 19, lines 20-28); when a reverse voltage is applied (a) increasing areas of the first depletion layer and the second depletion layer (col. 18, lines 46-51), (b) changing concentrations of electrons and holes in the rib waveguide (col. 18, line 52 through col. 19, line 5), and (c) increasing an effective refractive index change amount (col. 18, lines 46-51).
Therefore, it would have been obvious to a person having ordinary skill in the art, before the effective filing date of the claimed invention to have waveguide layers’ thicknesses as taught by Witzens et al. in the device of Zhou et al. since such modification is a matter of design choice for higher modulation performance (col. 19, lines 29-44). Further, it would have been obvious to a person having ordinary skill in the art to modify the device of Zhou et al. to, in response to an application of a reverse voltage, increase areas of depletion, change concentrations, and increase an effective refractive index change amount to provide Zhou et al. with the ability to lower transit time, reduce modulation loss, and have a higher limit to the maximum modulation frequency (col. 18, line 52 through col. 19, line 10). In addition, the limitation “the optical phase shifter is configured to…” is considered as a functional limitation. When the structure recited in the reference is substantially identical to that of the claims, a prima facie case of either anticipation or obviousness has been established. In re Best, 562 F.2d 1252, 1255, 195 USPQ 430, 433 (MPEP 2112.01 [R-07.2015]). In this case, Zhou et al. in view of Witzens et al. discloses an optical phase shifter comprising a slab waveguide and a rib waveguide having a first, second, and third rib layers, a first and second depletion layers that are substantially identical to that of the claimed invention, therefore the claimed properties or functions are presumed to be inherent or obvious. The burden is on the applicant to show that the prior art device does not possess the claimed properties or is not capable of these functional characteristics. (See MPEP 2112.01).
Regarding claim 10: Zhou et al./ Witzens et al. discloses the optical phase shifter of claim 1, wherein the rib waveguide further includes: a fourth rib waveguide layer (446) including silicon-germanium (SiGe) ([0024]) and disposed on the third rib waveguide layer (436); and a fifth rib waveguide layer (432) including silicon (Si) ([0024]) and disposed on the fourth rib waveguide layer (layer 432 is disposed on a side surface of layer 436 (fig. 4D)).
Regarding claim 11: Zhou et al. discloses a method for manufacturing an optical phase shifter, the method comprising: preparing a substrate structure in which a base substrate, an insulating layer, and a silicon (Si) layer are sequentially stacked (Fig. 17A);
forming a first empty space in a central portion of the silicon layer by etching the central portion of the silicon layer such that a level of the central portion of the silicon layer is lower than a level of each of both ends of the silicon layer (Fig. 17B; [0111]);
forming a slab waveguide in which a PN junction is formed at a junction between a first slab region (1330) and a second slab region (1340) by doping a first region of the etched silicon layer into a first conductivity type and doping a second region of the etched silicon layer, which is arranged side by side with the first region of the etched silicon layer, into a second conductivity type (Fig. 17C);
depositing a mask in the first empty space formed in the central portion of the silicon layer; forming a second empty space (1455) in the mask to expose a portion of the first region and a portion of the second region (Fig. 18A);
forming a rib waveguide in the second empty space (Fig. 18E), the rib waveguide including a first rib waveguide layer (1432) adjacent to the slab waveguide (1330 and 1340), a second rib waveguide layer (1442) stacked on the first rib waveguide layer, a third rib waveguide layer (1434) stacked on the second rib waveguide layer; and
forming electrodes on the first slab region and the second slab region of the slab waveguide (device has electrodes, see Par. 19),
wherein the first rib waveguide layer and the third rib waveguide layer include silicon (Si), and the second rib waveguide layer includes silicon-germanium (SiGe) (layers can be independently formed of various materials including Si and SiGe, see Par. 24),
wherein the first to third rib waveguide layers (1432, 1432, 1434 within the rib region) are doped into the first conductivity type (Par. 81),
wherein a first PN junction region is formed between the first slab region (1330) and the second slab region (1340), wherein a second PN junction region is formed between the second slab region (1340) and the first rib waveguide layer (1432) (figs. 4A-D).
Zhou et al. further discloses changing concentrations of electrons and holes in the rib waveguide (figs. 15A-B; [0103]-[0105]), but is silent with respect to and wherein the optical phase shifter is configured to respond to application of a reverse voltage by (a) increasing areas of the first depletion layer and the second depletion layer, (b) changing concentrations of electrons and holes in the rib waveguide, and (c) increasing an effective refractive index change amount. Zhou et al. also fails to teach a thickness of the first rib waveguide layer that is adjacent to the slab waveguide is thinner than a thickness of the third rib waveguide layer that are sequentially stacked.
Witzens et al. discloses a waveguide (27) having core layers (57, 55, 61) are sequentially stacked where a thickness of the first rib waveguide layer (57) is thinner than a thickness of the third rib waveguide layer (61)(fig. 6; col. 19, lines 20-28); when a reverse voltage is applied (a) increasing areas of the first depletion layer and the second depletion layer (col. 18, lines 46-51), (b) changing concentrations of electrons and holes in the rib waveguide (col. 18, line 52 through col. 19, line 5), and (c) increasing an effective refractive index change amount (col. 18, lines 46-51).
Therefore, it would have been obvious to a person having ordinary skill in the art, before the effective filing date of the claimed invention to have waveguide layers’ thicknesses of Zhou et al. as taught by Witzens et al. since such modification is a matter of design choice for higher modulation performance (col. 19, lines 29-44). Further, it would have been obvious to a person having ordinary skill in the art to modify the device of Zhou et al. to, in response to an application of a reverse voltage, increase areas of depletion, change concentrations, and increase an effective refractive index change amount to provide Zhou et al. with the ability to lower transit time, reduce modulation loss, and have a higher limit to the maximum modulation frequency (col. 18, line 52 through col. 19, line 10).
Regarding claim 12: Zhou et al./ Witzens et al. discloses the method of claim 11, wherein forming of the rib waveguide in the second empty space includes:
forming the first rib waveguide layer in the second empty space by growing silicon (Si) from the slab waveguide (rib waveguide layers may be epitaxially grown, see Par. 29);
forming a second rib waveguide layer on the first rib waveguide layer by growing silicon-germanium (Si-Ge) from the first rib waveguide layer (rib waveguide layers may be epitaxially grown, see Par. 29); and
forming a third rib waveguide layer on the second rib waveguide layer by growing silicon (Si) from the second rib waveguide layer (rib waveguide layers may be epitaxially grown, see Par. 29).
Regarding claim 13: Zhou discloses a method for manufacturing an optical phase shifter, the method comprising: preparing a substrate structure in which a base substrate, an insulating layer, and a silicon (Si) layer are sequentially stacked (Fig. 17A);
forming a first empty space in a central portion of the silicon layer by etching the central portion of the silicon layer such that a level of the central portion of the silicon layer is lower than a level of each of both ends of the silicon layer (Fig. 17B);
forming a slab waveguide in which a PN junction is formed at a junction between a first slab region (1330) and a second slab region (1340) by doping a first region of the etched silicon layer into a first conductivity type and doping a second region of the etched silicon layer, which is arranged side by side with the first region of the etched silicon layer, into a second conductivity type (Fig. 17C);
filling the first empty space with a rib waveguide, the rib waveguide including a first rib waveguide layer (1432) adjacent to the slab waveguide (1330 and 1340), a second rib waveguide layer (1442) stacked on the first rib waveguide layer, a third rib waveguide layer (1434) stacked on the second rib waveguide layer, and the first rib waveguide layer (1432), the second rib waveguide layer (1442), and the third rib waveguide layer (1434) are stacked along a surface profile of the slab waveguide;
performing planarization such that a top surface of each of both ends of the slab waveguide and a top surface of the rib waveguide filling the first empty space have a same level by removing the rib waveguide formed on the both ends of the slab waveguide while allowing the rib waveguide filling the first empty space to remain; etching the rib waveguide filling the first empty space to expose a portion (where 1334 deposited) of the first slab region of the slab waveguide and a portion (where 1344 deposited) of the second slab region of the slab waveguide (figs. 17G and 17I); and forming electrodes on the first slab region and the second slab region of the slab waveguide, respectively (device has electrodes, see Par. 19),
wherein the first rib waveguide layer and the third rib waveguide layer include silicon (Si), and the second rib waveguide layer includes silicon-germanium (SiGe) (layers can be independently formed of various materials including Si and SiGe, see Par. 24),
wherein the first to third rib waveguide layers (1432, 1432, 1434 within the rib region) are doped into the first conductivity type (Par. 81),
wherein a first PN junction region is formed between the first slab region (1330) and the second slab region (1340), wherein a second PN junction region is formed between the second slab region (1340) and the first rib waveguide layer (1432) (figs. 4A-D).
Zhou et al. further discloses changing concentrations of electrons and holes in the rib waveguide (figs. 15A-B; [0103]-[0105]), but is silent with respect to and wherein the optical phase shifter is configured to respond to application of a reverse voltage by (a) increasing areas of the first depletion layer and the second depletion layer, (b) changing concentrations of electrons and holes in the rib waveguide, and (c) increasing an effective refractive index change amount. Zhou et al. also fails to teach a thickness of the first rib waveguide layer that is adjacent to the slab waveguide is thinner than a thickness of the third rib waveguide layer that are sequentially stacked.
Witzens et al. discloses a waveguide (27) having core layers (57, 55, 61) are sequentially stacked where a thickness of the first rib waveguide layer (57) is thinner than a thickness of the third rib waveguide layer (61) (fig. 6; col. 19, lines 20-28); when a reverse voltage is applied (a) increasing areas of the first depletion layer and the second depletion layer (col. 18, lines 46-51), (b) changing concentrations of electrons and holes in the rib waveguide (col. 18, line 52 through col. 19, line 5), and (c) increasing an effective refractive index change amount (col. 18, lines 46-51).
Therefore, it would have been obvious to a person having ordinary skill in the art, before the effective filing date of the claimed invention to have waveguide layers’ thicknesses of Zhou et al. as taught by Witzens et al. since such modification is a matter of design choice for higher modulation performance (col. 19, lines 29-44). Further, it would have been obvious to a person having ordinary skill in the art to modify the device of Zhou et al. to, in response to an application of a reverse voltage, increase areas of depletion, change concentrations, and increase an effective refractive index change amount to provide Zhou et al. with the ability to lower transit time, reduce modulation loss, and have a higher limit to the maximum modulation frequency (col. 18, line 52 through col. 19, line 10).
Claim(s) 6-7 and 9 is/are rejected under 35 U.S.C. 103 as being unpatentable over Zhou et al. (US 2021/0373363 A1 hereinafter Zhou) in view of Witzens et al. (US 9036953 B2) as discuss above, and further in view of Gunn, III et al. (US 2006/0008223 A1).
Regarding claims 6-7, Zhou et al./ Witzens et al. discloses the optical phase shifter of claim 1 above, but fails to disclose that the first slab region includes the first slab region includes a first-first slab region having a first doping concentration, a first-second slab region that is arranged side-by-side with the first-first slab region and that has a second doping concentration that is lower than the first doping concentration, and a first-third slab region that is arranged side-by-side with the first-second slab region and that has a third doping concentration that is lower than the second doping concentration, wherein the slab waveguide is disposed such that the first-third slab region and the second-third slab region make contact with each other, and wherein the second slab region includes wherein the second slab region includes a second-first slab region having a fourth doping concentration, a second-second slab region that is arranged side-by-side with the second-first slab region and that has a fifth doping concentration that is lower than the fourth doping concentration, and a second-third slab region that is arranged side-by-side with the second-second slab region and that has a sixth doping concentration that is lower than the fifth doping concentration.
Gunn et al. teaches an optical phase shifter having a first slab region (920, Fig. 11) having a first-first slab region (920A, Fig. 11) having a first doping concentration (Par. 74), a first-second slab region (920B, Fig. 11) that is arranged side-by-side with the first-first slab region and that has a second doping concentration that is lower than the first doping concentration (Fig. 12; Par. 74), and a first-third slab region (920C, Fig. 11) that is arranged side-by-side with the first-second slab region and that has a third doping concentration that is lower than the second doping concentration (Fig. 12; Par. 74), wherein the slab waveguide is disposed such that the first-third slab region and the second-third slab region make contact with each other (Fig. 11), wherein the second slab region (930) includes a second-first slab region (930D) having a fourth doping concentration, a second-second slab region (930E) that is arranged side-by-side with the second-first slab region and that has a fifth doping concentration that is lower than the fourth doping concentration, and a second-third slab region (930F) that is arranged side-by-side with the second-second slab region and that has a sixth doping concentration that is lower than the fifth doping concentration (Figs. 11-12; [0074]).
Therefore, it would have been obvious to a person having ordinary skill in the art, before the effective filing date of the claimed invention, to have incorporated a stepped arrangement of dopant zones as taught by Gunn et al. within the optical phase shifter disclosed by Zhou et al./ Witzens et al. in order to optimize performance of the phase shifting device.
Regarding claim 9: Zhou et al./ Witzens et al. discloses the optical phase shifter of claim 1 above, but does not explicitly disclose in a first area in which the second slab region and the first rib waveguide layer overlap, the optical phase shifter has a first modulation efficiency and a first optical modulation speed, in a second area in which the second slab region and the first rib waveguide layer overlap, the optical phase shifter has a second modulation efficiency and a second optical modulation speed, the first area is wider than the second area, the first optical modulation efficiency is improved compared to the second optical modulation efficiency, and the first optical modulation speed is reduced compared to the second optical modulation speed.
Gunn et al. teaches in a first area (930D and 930E) in which the second slab region (930) and the first rib waveguide layer overlap, the optical phase shifter has a first modulation efficiency and a first optical modulation speed, in a second area (930F) in which the second slab region and the first rib waveguide layer overlap, the optical phase shifter has a second modulation efficiency and a second optical modulation speed, the first area is wider than the second area (930F) (fig. 11). Since the first area (930D and 930E) has higher doping than the second area (930F) (fig. 12; [0074-0076]), and since increasing the doping level generally enhances the modulation speed and reduced efficiency, the first optical modulation efficiency is improved compared to the second optical modulation efficiency, and the first optical modulation speed is reduced compared to the second optical modulation speed. Accordingly, it would have been obvious to a person having ordinary skill in the art, before the effective filing date of the claimed invention to have Zhou et al./ Witzens et al.’s doping distribution levels as taught by Gunn et al. for intended use to control modulation speed and efficiency as desired (Gunn et al. [0076-0077]).
Claim(s) 8 is/are rejected under 35 U.S.C. 103 as being unpatentable over Zhou et al. (US 2021/0373363 A1) in view of Witzens et al. (US 9036953 B2) and Gunn, III et al. (US 2006/0008223 A1) as discuss above, and further in view of Chern (US 2021/0341766 A1).
Regarding claim 8, Zhou/ Witzens / Gunn discloses the optical phase shifter of claim 7.
Zhou/ Witzens / Gunn fails to disclose that a thickness of the first-first slab region is thicker than a thickness of each of the first-second slab region and the first-third slab region, and a thickness of the second-first slab region is thicker than a thickness of each of the second-second slab region and the second-third slab region.
Chern teaches an optical phase shifter (Fig. 17C) where a doped slab region (236 and 238, Fig. 17C) has a width that varies from thicker in the highly doped regions furthest from the central rib waveguide (218, 228, Fig. 17C) to thinner in the lower doped regions closest to the rib waveguide (218, 219). Chern implements this arrangement as a way to optimize performance of the optical phase shifter (Par. 25). Therefore, it would have been obvious to a person having ordinary skill in the art, before the effective filing date of the claimed invention, to have incorporated differential thickness of the slab waveguide as taught by Chern, within the optical phase shifter disclosed by Zhou/ Witzens / Gunn in order to optimize performance of the phase shifting device.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. Yu et al. (CN 110494800 A – fig. 2C) discloses a thickness of the first rib waveguide layer that is adjacent to the slab waveguide is thinner than a thickness of the third rib waveguide layer.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Uyen-Chau N. Le whose telephone number is (571)272-2397. The examiner can normally be reached Monday-Friday, 9:00am-5:30pm.
Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice.
If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Kiesha R. Bryant can be reached at (571) 272-3606. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/UYEN CHAU N LE/Supervisory Patent Examiner, Art Unit 2874
Prosecution Insights