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 .
Response to Pre-Appeal
In view of the pre-appeal filed on august 12, 2025, PROSECUTION IS HEREBY REOPENED. New grounds of rejection are set forth below.
Drawings
Ten (10) replacement sheets of drawings were filed on March 27, 2025.
The drawings are objected to because reference number 114 in Figure 4, which points to the output waveguides, should be 116. Reference number 114 refers to the reflective surface of the echelle grating, as labeled in Figure 1, and reference number 116 refers to the output waveguides as labeled in Figure 1.
Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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, 3, 9, 11, and 13-16 are rejected under 35 U.S.C. 103 as being unpatentable over Oguma et al. (US 2022/0269001 A1) in view of Yamazaki (EP 1 548 471 B1) and So et al. (WO 2004/061498 A1).
Regarding claim 1; Oguma et al. discloses an apparatus (see Figure 2) comprising:
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a first waveguide (first waveguide; see annotated Figure 2 above);
a first coupler (first coupler) to couple light from the first waveguide (first waveguide) into a second waveguide (second waveguide) and a third waveguide (third waveguide);
a second coupler (directional coupler 303, second coupler; see annotated Figure 2 above) to mix light in the second waveguide (second waveguide) and the third waveguide (third waveguide);
a grating (arrayed waveguide grating, AWG 302), wherein the second waveguide (second waveguide) and the third waveguide (third waveguide) are positioned as an input to the grating (302);
a plurality of output waveguides (output waveguides; see annotated Figure 2 above), wherein each of the plurality of output waveguides (output waveguides) is configured as an output to the grating (302).
Oguma et al. does not disclose one or more auxiliary structures positioned near the second waveguide and the third waveguide to modify a spatial mode of a symmetric supermode supported by the second waveguide and the third waveguide at the input to the grating.
Although not specifically defined in claim 1, the auxiliary structures (402 in Figure 4 of the present application) of the present invention are illustrated as a ramp placed between the waveguides. It’s generally known in the art that ramps may be placed between optical waveguides at the input and/or outputs of slab waveguide regions for the purpose of minimizing coupling loss. For example, Yamazaki (EP 1 548 471 B1) discloses that wedge-liked tapered waveguide ramps (13) are formed between arrayed waveguides (121 through 125) at a region where the waveguides are coupled to a slab waveguide (11), wherein optical signals having been propagated through the slab waveguide are incident without leakage on the connections with the arrayed waveguides to obtain low loss, and reversibly, optical signals having been propagated through the arrayed waveguides can be incident on the slab waveguide at a low loss (see paragraphs 5 and 6 of Yamazaki). Additionally, So et al. (WO 2004/061498 A1) teaches that a vertically tapered waveguide, inserted between input/output waveguides, improvise insertion loss at a slab/waveguide interface of an arrayed waveguide grating structure (see the abstract and Figures 2a and 3).
Thus, before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to incorporate one or more auxiliary structures in the form of vertically tapered waveguide ramps near the second and third waveguides at the region where the second and third waveguides are coupled to the slab waveguide to modify a spatial mode of a symmetric supermode (this inherently happens due to the presence of the ramp structures) supported by the second waveguide and the third waveguide at the input of the grating to minimize insertion loss.
Regarding claim 3; Oguma et al. in view of Yamazaki and So et al. teaches the apparatus of claim 1 as applied above, wherein the one or more auxiliary structures comprises a ramp (ramps taught by Yamazaki and So et al.; see the rejection of claim 1 above) positioned between the second waveguide and the third waveguide, wherein the ramp is to increase coupling of a center wavelength of each of a plurality of channels (the coupling is increased by a reduction in insertion loss) to a corresponding output waveguide of the plurality of output waveguides (see Figure 2 of Oguma et al. annotated above).
Regarding claim 9; Oguma et al. discloses an apparatus comprising:
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a first waveguide (first waveguide; see annotated Figure 2 above) and a second waveguide (second waveguide; see annotated Figure 2 above), the first waveguide and the second waveguide supporting at least two supermodes (see Figures 6 and 7; see paragraphs 16-18);
a slab wavelength demultiplexer (302), wherein the first waveguide (first waveguide) and the second waveguide (second waveguide) are positioned as an input to the slab wavelength demultiplexer (302);
a plurality of output waveguides (output wav3guides; see Figure 2 annotated above), wherein each of the plurality of output waveguides is configured as an output to the slab wavelength demultiplexer (302).
Oguma et al. does not disclose one or more auxiliary structures positioned near the first waveguide and the second waveguide to modify the at least two supermodes supported by the first waveguide and the second waveguide at the input to the slab wavelength demultiplexer.
Although not specifically defined in claim 9, the auxiliary structures (402 in Figure 4 of the present application) of the present invention are illustrated as a ramp placed between the waveguides. It’s generally known in the art that ramps may be placed between optical waveguides at the input and/or outputs of slab waveguide regions for the purpose of minimizing coupling loss. For example, Yamazaki (EP 1 548 471 B1) discloses that wedge-liked tapered waveguide ramps (13) are formed between arrayed waveguides (121 through 125) at a region where the waveguides are coupled to a slab waveguide (11), wherein optical signals having been propagated through the slab waveguide are incident without leakage on the connections with the arrayed waveguides to obtain low loss, and reversibly, optical signals having been propagated through the arrayed waveguides can be incident on the slab waveguide at a low loss (see paragraphs 5 and 6 of Yamazaki). Additionally, So et al. (WO 2004/061498 A1) teaches that a vertically tapered waveguide, inserted between input/output waveguides, improvise insertion loss at a slab/waveguide interface of an arrayed waveguide grating structure (see the abstract and Figure 2a and 3).
Thus, before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to incorporate one or more auxiliary structures in the form of vertically tapered waveguide ramps positioned near the first waveguide and the second waveguide to modify the at least two supermodes supported by the first waveguide and the second waveguide at the input to the slab wavelength demultiplexer (this inherently happens due to the presence of the ramp structures) supported by the second waveguide and the third waveguide at the input of the grating to minimize insertion loss.
Regarding claim 11; Oguma et al. discloses that the slab wavelength demultiplexer is an arrayed waveguide grating (AWG 302; see Figure 2).
Regarding claim 13; Oguma et al., Yamazaki, and So et al., as applied to claim 9, teach that the one or more auxiliary structures comprises a ramp positioned between the first waveguide and the second waveguide (see the rejection of claim 9 above), wherein the ramp is to increase coupling of a center wavelength of each of a plurality of channels to a corresponding output waveguide of the plurality of output waveguides (the coupling is increased by minimizing insertion loss at the interface between the first and second waveguides and the slab waveguide).
Regarding claim 14; Oguma et al. discloses a coupler (first coupler; see Figure 2 annotated above with respect to claim 9) coupled to the first waveguide (first waveguide) and the second waveguide (second waveguide), wherein the coupler (first coupler), the first waveguide, and the second waveguide form an unbalanced interferometer (MZI interferometer; see Figure 2).
Regarding claim 15; Oguma et al., Yamazaki, and So et al. teach and/or suggest the apparatus of claim 9 as applied above. Oguma et al. discloses an alternative embodiment, (see Figure 4 annotated below), wherein a third waveguide (third waveguides; see annotated Figure 4) is provided between the first waveguide (first waveguide) and the second waveguide (second waveguide), wherein the first waveguide, the second waveguide, and the third waveguide support at least two supermodes. A person of ordinary skill in the art, before the effective filing date of the present invention, would have found it obvious to use the alternative demultiplexer embodiment of Oguma et al., and to provide the one or more auxiliary structures suggested by the teachings of Yamazaki and So et al. as discussed above with respect to claim 9, comprising a first auxiliary structure between the first waveguide and the third waveguide and a second auxiliary structure between the second waveguide and the third waveguide, since both Yamazaki and So et al. teach that ramps may be at each location between two waveguides.
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Regarding claim 16; the first waveguide, second waveguide, and third waveguide (see annotated Figure 4 of Oguma et al. above) form a first arm, a second arm, and a third arm, respectively, of a three-arm interferometer.
Claims 4-6 are rejected under 35 U.S.C. 103 as being unpatentable over Oguma et al. (US 2022/0269001 A1) in view of Yamazaki (EP 1 548 471 B1) and So et al. (WO 2004/061498 A1), and in further view of Suzuki et al. (US 2006/0222296 A1).
Regarding claims 4 and 5; Oguma et al., Yamazaki, and So et al. teach and/or suggest the apparatus of claim 1 as applied above, but fail to disclose that each of the first waveguide, the second waveguide, and the third waveguide has a core material and a cladding material, wherein a difference in index of refraction between the core material and the cladding material is at least 0.1 over a wavelength range of the apparatus, wherein the core material is silicon nitride and the cladding material is silicon dioxide.
Silicon nitride and silicon dioxide are common materials utilized to form waveguides in silicon photonic devices. Suzuki et al. teaches a silicon photonic wavelength demultiplexer (Fig. 5) wherein the waveguide core is formed of silicon nitride and the cladding is formed of silicon dioxide and notes that the relatively high difference in refractive index between the two materials is ideal for light confinement in the waveguide (Par. 58). Suzuki further teaches this difference in refractive index is greater than 8% or roughly 0.12 (Par. 58, the examiner notes that where the refractive index of SiO2 is n = 1.5, an 8% difference is 0.12). 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 the silicon nitride core and silicon dioxide cladding of the waveguides taught by Suzuki in the demultiplexing device disclosed by Nara/Sugita in order to achieve a difference of refractive index greater than 0.1 resulting in desired light confinement in the apparatus.
Regarding claim 6; the wavelength of light transmitted over the demultiplexer and the temperature-dependent shift are properties of the device material and structure. Obuma et al., Yamazaki, So et al., and Suzuki teach and/or suggest the apparatus comprised of silicon materials which are known to be transparent to wavelengths in the range of 1,250 and 1,370 nanometers, and having met all of the defined structural limitations, implicitly suggests an apparatus, wherein the wavelength range of the apparatus may optionally be within 1,250 and 1,370 nanometers, i.e. a person of ordinary skill in the art may choose to transmit an optical signals within this wavelength range through the apparatus, and wherein a temperature-dependent shift in center wavelength for each of a plurality of channels of the apparatus is less than one nanometer over a range of zero to eighty degrees Celsius, since temperature-dependent shift of a center wavelength is determined by the material and structural properties of the prior, all of which are addressed above.
When a structure recited in a reference is substantially identical to that of the claims, claimed properties or functions are presumed to be inherent (see MPEP 2112.01). The patentability of a product depends only on the claimed structural limitations of the product. 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 7 is rejected under 35 U.S.C. 103 as being unpatentable over Oguma et al. (US 2022/0269001 A1) in view of Yamazaki (EP 1 548 471 B1) and So et al. (WO 2004/061498 A1), and in further view of Laming et al. (US 2004/0047560 A1).
Regarding claim 7; Oguma et al., Yamazaki, and So et al. teach and/or suggest the apparatus of claim 1 as applied above, but do not disclose a plurality of detectors, wherein each of the plurality of detectors is coupled to one of the plurality of output waveguides, wherein each of the plurality of output waveguides is a single mode waveguide.
Oguma et al. teaches that the apparatus (see Figure 2) is an AWG wavelength demultiplexer (see paragraph 8). Laming et al. discloses an optical power monitor for a demultiplexer (see Figure 3), wherein an AWG demultiplexer includes single mode output waveguides (33; see paragraph 26) and a plurality of detectors (24; see paragraph 25) are provided, wherein each of the plurality of detectors (24) is coupled to one of the plurality of single-mode output waveguides (33) for the purpose of monitoring the power of the demultiplexed channels and providing power control.
Thus, before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to provide a plurality of detectors, wherein each of the plurality of detectors is coupled to one of the plurality of output waveguides, wherein each of the plurality of output waveguides is a single mode waveguide in the AWG demultiplexer of Oguma et al. for the purpose of monitoring the power of the demultiplexed channels and providing power control.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Oguma et al. (US 2022/0269001 A1) in view of Yamazaki (EP 1 548 471 B1) and So et al. (WO 2004/061498 A1), and in further view of Bulthuis (US 2012/0087667 A1).
Regarding claim 8; Oguma et al., Yamazaki, and So et al. teach and/or suggest the apparatus of claim 1 as applied above, wherein each of the plurality of output waveguides (output waveguides; see Figure 2 of Oguma et al., annotated above) defines a channel having a center wavelength, wherein the second waveguide (second waveguide) has a first optical path length from the first coupler (first coupler) to the second coupler (second coupler, 303), wherein the third waveguide (third waveguide) has a second optical path length from the first coupler (first coupler) to the second coupler (second coupler 303), wherein a difference between the first optical path length and the second optical path length defines a free spectral range of an interferometer formed by the first coupler, the second coupler, the second waveguide, and the third waveguide (Mach-Zehnder interferometer, MZI 304; see Figure 2 and paragraph 8), and wherein the free spectral range of the interferometer is approximately equal to a spacing (channel spacing) between center wavelengths (center wavelength λc; see paragraph 59) of adjacent channels defined by the plurality of output waveguides (this is inherent to the AWG demultiplexer structure of Oguma et al.).
Oguma et al., Yamazaki, and So et al. do not specify that a wavelength range of the apparatus is within 1,250 and 1,370 nanometers. AWGs are known to support multiple commonly used wavelength bands, including the O-band, which ranges from 1260 to 1360 nm (see Classification of Spectral Bands table on page 1 of Bulthuis). Before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to transmit any desired wavelength range over the apparatus, including a wavelength range within 1250 and 1370 nanometers, since theses wavelengths are known to be transmitted over AWG demultiplexers in the art, for the purpose of transmitting information over a desired, commonly used wavelength band of choice.
Claims 10 and 21 are rejected under 35 U.S.C. 103 as being unpatentable over Oguma et al. (US 2022/0269001 A1) in view of Yamazaki (EP 1 548 471 B1) and So et al. (WO 2004/061498 A1), and in further view of He et al. (US 2002/0131685 A1).
Regarding claim 10; Oguma et al., Yamazaki, and So et al. teach and/or suggest the apparatus of claim 9 as applied above, wherein the slab wavelength demultiplexer is a grating (arrayed waveguide grating 302, comprising two slab waveguides with an array of waveguides there-between; see Figure 2 of Oguma et al.) comprising a slab expansion region (slab waveguides), but does not disclose that the grating comprises a slab expansion region and a reflective surface. Echelle gratings, which comprising a slab expansion region and a reflective surface, are known to be used in alternative to arrayed waveguide gratings (AWGs) for the purpose of providing a folded, more compact demultiplexer. For example: He et al. teaches that arrayed waveguide gratings (see Figure 1a) and echelle gratings (see Figure 1b) are known alternative demultiplexers (see paragraph 38).
Thus, before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to use an echelle grating comprising a slab expansion region and a reflective surface in alternative to the arrayed waveguide grating (302) of Oguma et al. for the purpose of providing a more compact design and smaller footprint, since echelle gratings and arrayed waveguide gratings were known alternative demultiplexers in the prior art, and one of ordinary skill could have combined the elements by known coupling methods with no change in their respective functions to yield predictable results. KSR International Co. v. Teleflex Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007).
Regarding claim 21; Oguma et al., Yamazaki, and So et al. teach and/or suggest the apparatus of claim 9 as applied above, further comprising a ramp (ramps as taught by either Yamazaki and/or So et al.; see the rejection of claim 9 above) positioned between the first waveguide and the second waveguide before the slab expansion region, wherein the ramp is to increase coupling of a center wavelength of each of a plurality of channels to a corresponding output waveguide of the plurality of output waveguides by increasing, at the ramp, an amplitude of a spatial mode of a symmetric supermode supported by the first waveguide and second waveguide (the ramps taught by Yamazaki and So et al. inherently perform this function).
Oguma et al. Yamazaki, and So et al. do not teach that the slab wavelength demultiplexer is a grating, the grating comprising a slab expansion region and a reflective surface. Oguma et al. teaches that the slab wavelength demultiplexer is a grating (arrayed waveguide grating 302, comprising two slab waveguides with an array of waveguides there-between; see Figure 2 of Oguma et al.) comprising a slab expansion region (slab waveguides). Echelle gratings, which comprising a slab expansion region and a reflective surface, are known to be used in alternative to arrayed waveguide gratings (AWGs) for the purpose of providing a folded, more compact demultiplexer. For example: He et al. teaches that arrayed waveguide gratings (see Figure 1a) and echelle gratings (see Figure 1b) are known alternative demultiplexers (see paragraph 38).
Thus, before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to use an echelle grating comprising a slab expansion region and a reflective surface in alternative to the arrayed waveguide grating (302) of Oguma et al. for the purpose of providing a more compact design and smaller footprint, since echelle gratings and arrayed waveguide gratings were known alternative demultiplexers in the prior art, and one of ordinary skill could have combined the elements by known coupling methods with no change in their respective functions to yield predictable results. KSR International Co. v. Teleflex Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007).
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Oguma et al. (US 2022/0269001 A1) in view of Yamazaki (EP 1 548 471 B1) and So et al. (WO 2004/061498 A1), and in further view of Park et al. (US 2015/0078708 A1).
Regarding claim 12; Oguma et al., Yamazaki, and So et al. teaches and/or suggest the apparatus of claim 9 as applied above, wherein one or more auxiliary structures are positioned between the first waveguide and the second waveguide, wherein the auxiliary structures increase coupling of a center wavelength of each of a plurality of channels to a corresponding output waveguide of the plurality of output waveguides, but does not disclose that the one or more auxiliary structures comprises a block with a flat top. Park et al. discloses alternative auxiliary structures (see annotated Figure 9A below) comprising a block with flat surfaces between waveguides (waveguides 114 separated by trenches 115; see Figure 9A) at the region where the waveguides are coupled to a slab waveguide (coupler slab 112).
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Therefore, before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to incorporate auxiliary structure comprising a block with flat surfaces between the waveguides in alternative to the ramp auxiliary structures for the purpose of obtaining desired optical coupling results, since this was a known alterative auxiliary structure of prior art, and one of ordinary skill could have combined the elements by known coupling methods with no change in their respective functions to yield predictable results. KSR International Co. v. Teleflex Inc., 550 U.S. 398, 82 USPQ2d 1385 (2007).
Claim 17 is rejected under 35 U.S.C. 103 as being unpatentable over Oguma et al. (US 2022/0269001 A1) in view of Yamazaki (EP 1 548 471 B1) and So et al. (WO 2004/061498 A1), and in further view of Kato et al. (US 2001/0012424 A1).
Regarding claim 17; Oguma et al., Yamazaki, and So et al. teaches and/or suggest the apparatus of claim 9 as applied above, but fail to teach that each of the first waveguide and the second waveguide has a core material and a cladding material, wherein the core material is germanium-doped silica and the cladding material is silicon dioxide. Optical waveguide cores are routinely made of Germanium-dope silica and cladding is routinely made of silicon dioxide in the art, wherein the selection of these respective materials for core and cladding materials provides a relative refractive index difference allowing for light to be confined within the core. For example, Kato et al. (see Figures 4-6) teaches that AWG optical multiplexer/demultiplexer devices may include cladding (22, 24, 31b, 31d) and a core (23, 32c), wherein the cladding may be comprised of silicon dioxide (see paragraphs 58 and 73) and the core may comprise of (germanium-doped silicon dioxide, i.e. germanium doped silica; see paragraphs 59 and 74).
Thus, before the effective filing date of the present invention, a person would have found it obvious to form the device of Oguma et al., wherein each of the first waveguide and the second waveguide has a core material and a cladding material, wherein the core material is germanium-doped silica and the cladding material is silicon dioxide, since these materials are known to be used to form claddings and cores in the art, and since it has been held to be within the general skill of a worker in the art to select a known material on the basis of its suitability for the intended use. In re Leshin, 125 USPQ 416.
Claims 18 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Oguma et al. (US 2022/0269001 A1) in view of Yamazaki (EP 1 548 471 B1) and So et al. (WO 2004/061498 A1), and further in view of Bulthuis et al. (US 2003/0063858 A1) and Lee et al. (US 2004/0042752 A1).
Regarding claims 18 and 20; As applied to claim 1 above, Oguma et al. (see Figure 2, annotated below), Yamazaki, and So et al. teach and/or suggest a method for forming an apparatus, the method comprising:
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forming, on a cladding layer (the cladding layer inherently surrounds the waveguide core),
a first waveguide (first waveguide; see annotated Figure 2 above),
a second waveguide (second waveguide), a
third waveguide (third waveguide),
a first coupler (first coupler),
a second coupler (second coupler, 303),
a grating (arrayed waveguide grating 302), and
a plurality of output waveguides (output waveguides); and
forming one or more auxiliary structures (ramps as taught by Yamazaki and/or So et al.; see the rejection of claim 1 above) positioned near the second waveguide and the third waveguide to modify supermodes supported by the second waveguide and the third waveguide at the input to the grating (the presence of ramps at the junction of the waveguides and the slab waveguide inherently performs this function),
wherein the first coupler (first coupler; see Figure 2 annotated above) is to couple light from the first waveguide (first waveguide) into the second waveguide (second waveguide) and the third waveguide (third waveguide),
wherein each of the second waveguide and the third waveguide is connected to the first coupler (first coupler) and the second coupler (second coupler 303),
wherein the second waveguide and the third waveguide are positioned as an input to the grating (arrayed waveguide grating 302; see Figure 2 annotated above), and
wherein each of the plurality of output waveguides (output waveguides) is configured as an output to the grating (302);
wherein the one or more auxiliary structures (ramps suggested by the teachings of Yamazaki and/or So et al.) comprises a ramp positioned between the second waveguide and the third waveguide, wherein the ramp is to increase coupling of a center wavelength of each of a plurality of channels to a corresponding output waveguide of the plurality of output waveguides (this is an inherent function of a ramp at the junction between the waveguides and the slab waveguide),
Oguma et al., Yamazaki, and So et al. do not disclose that forming steps require photolithography, wherein photolithographically forming the ramp comprising photolithographically forming the ramp with use of grayscale photolithography.
Bulthuis et al. teaches that transmission waveguides and slab waveguides are typically formed with standard photolithographic techniques (see paragraph 5). Lee et al. teaches that waveguides, slab waveguides, and ramps (440; see Figure 4F) are made by lithographic processes (see paragraph 33) with the use of a gray scale mask (see paragraph 35) to form the ramps (vertical taper). Thus, before the effective filing date of the present invention, a person of ordinary skill in the art would have found it obvious to form the waveguides and slab waveguides with standard photolithography processes and to form the ramps with a gray scale photolithography process for the purpose of using standard techniques known to form similar elements in the art.
Conclusion
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/UYEN CHAU N LE/Supervisory Patent Examiner, Art Unit 2874