Detailed Office 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 .
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 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.
Examiner’s Comments – Rejection of Independent Claims 1 and 11
Independent claims 1 and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Jonathan St-Yves (Contra-directional couplers as optical filters on the silicon on insulator platform, Dissertation, Québec, Canada, 2017; “St-Yves”) in view of Ling et al. (11,002,980; “Ling”).
Examiner’s Comments – Claim Language
The examiner notes that the readability of claims reciting “CWDM” and/or “DWDM” would benefit, for example, from preceding recitations of ‘coarse wavelength division multiplexer’ and/or ‘dense wavelength division multiplexer,’ respectively.
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 of this title, 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.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-19
Claims 1-19 are rejected under 35 U.S.C. 103 as being unpatentable over Jonathan St-Yves (Contra-directional couplers as optical filters on the silicon on insulator platform, Dissertation, Québec, Canada, 2017; “St-Yves”) in view of Ling et al. (11,002,980; “Ling”).
Regarding independent claim 1, St-Yves discloses in figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text, embodiments of contra-directional couplers including operational characteristics (for example, wavelength-selective coupling), material characteristics (for example, indices of refraction), geometries (for example, widths, gaps, and tapers), and gratings (for example, chirped gratings): “First, the waveguides do not have the same width. This lead to different propagation constants in the waveguides and suppresses the normal co-directional coupling. Second, a periodic dielectric perturbation causes light at a certain wavelength to be coupled into the other waveguide in the backward direction, similar to how Bragg gratings operate.” St-Yves – Selected Text.
St-Yves – Figures 2.1 and 2.2
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St-Yves – Selected Text
Chapter 2. Contra-directional couplers - Principles and simulation
This chapter describes the fundamental and operating principles of contra-directional couplers, based on [21]. It covers the physical structure, as well as the phenomena observed in this structure and how to simulate them. Beyond re-interpreting this article, this chapter also describes the methodology to simulate apodized contra-directional coupler response and provide an analysis of the phase noise present in fabrication.
2.1 Principle of operation
Contra-directional couplers (contra-DCs or CDCs) are similar to directional couplers in geometry _ two waveguides that are placed very close to each other, allowing coupling between them. Compared to directional couplers, there are two main differences. First, the waveguides do not have the same width. This lead to different propagation constants in the waveguides and suppresses the normal co-directional coupling. Second, a periodic dielectric perturbation causes light at a certain wavelength to be coupled into the other waveguide in the backward direction, similar to how Bragg gratings operate.
2.2 Geometry
Figure 2.1 shows a schematic of a contra-DC, with the tapers needed to readily connect to routing waveguides. Both the width and the spacing between the waveguides must be adiabatically changed with tapers to interface between the grating section and the routing waveguides. The grating section is where light is reflected. Figure 2.2 shows a close up on this structure. In this research, the waveguides are made of silicon, covered on all sides by silicon dioxide. The top and bottom waveguides have different widths w1 and w2, resulting in different effective indices of the mode mainly confined in each (ne_,1 and ne_,2). A perturbation of constant period _ is etched on both the inside and outside walls of each waveguide, creating alternating sections of smaller and large waveguides gap. The outside wall is patterned in this way to keep the effective index the same in both the close and far sections in order to reduce the Bragg reflections in the input waveguide [23].
In this configuration, only the band around wavelength _D is coupled from the input to the drop port, while the rest of the light goes through. The second-order coupling would be at _D=2 where silicon is not transparent, assuming _D is in the telecommunication band from around 1200 to 1600 nm.
Further regarding claim 1, Ling discloses in figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text, embodiments of cascaded contra-directional couplers configured such that wavelengths are reflected/extracted from an input spectrum by order of increasing wavelength with each wavelength that is reflected/extracted at a specific contra-directional coupler is not reflected/extracted by any subsequent/downstream directional couplers. Ling, figures 5 and 6, and column 6, lines 14-27 (“ Thus, responsive to receiving an optical signal 530 comprising a plurality of wavelengths λ.sub.0, λ.sub.1, λ.sub.2, λ.sub.3 at the input port 510, the grating 515-0 reflects the wavelength λ.sub.0 and transmits the remaining wavelengths λ.sub.1, λ.sub.2, λ.sub.3. The mode multiplexer 520-0 receives the wavelength λ.sub.0 and provides the wavelength λ.sub.0 (with the mode converted to a fundamental mode) to the output port 525-0 as an optical signal 535-0. The grating 515-1 receives the wavelengths λ.sub.1, λ.sub.2, λ.sub.3, reflects the wavelength λ.sub.1, and transmits the remaining wavelengths λ.sub.2, λ.sub.3. The mode multiplexer 520-1 receives the wavelength λ.sub.1 and provides the wavelength λ.sub.1 (with the mode converted to a fundamental mode) to the output port 525-1 as an optical signal 535-1.”).
Ling - Figures 5 and 8-11
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Ling – Selected Text
Abstract. Aspects described herein include an optical apparatus comprising an input port configured to receive an optical signal comprising a plurality of wavelengths, and a plurality of output ports. Each output port is configured to output a respective wavelength of the plurality of wavelengths. The optical apparatus further comprises a first plurality of two-mode Bragg gratings in a cascaded arrangement. Each grating of the first plurality of two-mode Bragg gratings is configured to reflect a respective wavelength of the plurality of wavelengths toward a respective output port of the plurality of output ports, and transmit any remaining wavelengths of the plurality of wavelengths.
(2) WDM schemes support multiple channels through a light-carrying medium, such as an optical waveguide or an optical fiber. WDM schemes are typically distinguished by the spacing between wavelengths. For example, a “normal” WDM system supports 2 channels spaced apart by 240 nanometers (nm), a coarse WDM (CWDM) system supports up to eighteen (18) channels that are spaced apart by 20 nm, and a dense WDM (DWDM) system supports up to eighty (80) channels that are spaced apart by 0.4 nm. Due to the wavelength spacing, a CWDM system tends to be more tolerant than a DWDM system and does not require high-precision controlled laser sources. As a result, a CWDM system tends to be less expensive and consumes less power.
(18) The optical apparatus comprises a plurality of transmitters 105-1, 105-2, 105-3, . . . , 105-M (generically, a transmitter 105) that provide optical signals via a respective plurality of optical links 110-1, 110-2, 110-3, . . . , 110-M (generically, an optical link 110) to a multiplexer 115. In some embodiments, each transmitter 105 comprises a laser source generating a respective optical signal (e.g., an unmodulated continuous wave (CW) optical signal) having a respective wavelength. The wavelengths of the optical signals may be selected according to a predefined multiplexing scheme, such as WDM, DWDM, or CWDM. Each transmitter 105 may further comprise an optical modulator configured to modulate the respective optical signal, and may further comprise circuitry for further processing of the respective optical signal. In some embodiments, the optical links 110 are optical waveguides formed in a silicon photonic chip. In other embodiments, the optical links 110 are optical fibers.
(5) FIGS. 5 and 6 are diagrams of exemplary implementations of a demultiplexer with a cascaded arrangement of two-mode Bragg gratings, according to one or more embodiments.
(6) FIGS. 7 and 8 are diagrams of exemplary implementations of a demultiplexer with mitigated crosstalk, according to one or more embodiments.
(7) FIG. 9 are graphs illustrating operation of the two-mode Bragg gratings as bandpass filters, according to one or more embodiments.
(8) FIG. 10 are graphs illustrating operation of the two-mode Bragg gratings as low-pass filters, according to one or more embodiments.
(9) FIG. 11 is a graph illustrating operation of the two-mode Bragg gratings as bandpass filters having partially overlapping passbands, according to one or more embodiments.
(31) FIGS. 5 and 6 are diagrams 500, 600 of exemplary implementations of a demultiplexer 505, 605 with a cascaded arrangement of two-mode Bragg gratings, according to one or more embodiments. The features illustrated in the diagrams 500, 600 may be used in conjunction with other embodiments. For example, mode multiplexers and two-mode Bragg gratings included in the demultiplexers 505, 605 may be configured as shown in FIG. 4.
(32) In the diagram 500, the demultiplexer 505 comprises an input port 510 and a plurality of two-mode Bragg gratings 515-0, 515-1, 515-2 (which are also referred to herein as “gratings” or “Bragg gratings”) in a cascaded arrangement (which may alternately be referred to as a “serial” arrangement). Each grating 515-0, 515-1, 515-2 reflects a respective wavelength, and transmits any remaining wavelengths. For example, the grating 515-0 reflects a first wavelength via a drop port, and transmits at least one wavelength via an output port to gratings 515-1, 515-2 that are downstream of the grating 515-0.
(33) The gratings 515-0, 515-1, 515-2 may have any suitable filter responses for separating the respective wavelength for reflecting. In some embodiments, the gratings 510-0, 515-1, 515-2 are bandpass filters, which may have non-overlapping or partially overlapping passbands. For examples, the gratings 515-0, 515-1, 515-2 may have partially overlapping passbands with a center wavelength and an upper roll-off wavelength selected such that a range of the respective wavelength reflected by the grating 510-0, 515-1, 515-2 is entirely included between the center wavelength and the upper roll-off wavelength. In other embodiments, the gratings 515-0, 515-1, 515-2 are low-pass filters and may have successively greater roll-off wavelengths.
(34) In some embodiments, the demultiplexer 505 further comprises a plurality of mode multiplexers 520-0, 520-1, 520-2. Each mode multiplexer of the plurality of mode multiplexers 520-0, 520-1, 520-2 receives the wavelength reflected by a respective grating 515-0, 515-1, 515-2. Each mode multiplexer converts the mode of the reflected wavelength (e.g., a first-order TE mode) into a fundamental TE mode. The plurality of mode multiplexers 520-0, 520-1, 520-2 may have any suitable implementation, e.g., using on-resonance and off-resonance switching rings. Each mode multiplexer 520-0, 520-1, 520-2 has an output that is coupled with a respective output port 525-0, 525-1, 525-2 of a plurality of output ports 525-0, 525-1, 525-2, 525-3 of the demultiplexer 505. In other embodiments, the plurality of mode multiplexers 520-0, 520-1, 520-2 may be omitted, such that the gratings 515-0, 515-1, 515-2 provide the reflected wavelengths (e.g., as a first order or higher mode) directly to the output ports 525-0, 525-1, 525-2.
(35) Thus, responsive to receiving an optical signal 530 comprising a plurality of wavelengths λ.sub.0, λ.sub.1, λ.sub.2, λ.sub.3 at the input port 510, the grating 515-0 reflects the wavelength λ.sub.0 and transmits the remaining wavelengths λ.sub.1, λ.sub.2, λ.sub.3. The mode multiplexer 520-0 receives the wavelength λ.sub.0 and provides the wavelength λ.sub.0 (with the mode converted to a fundamental mode) to the output port 525-0 as an optical signal 535-0. The grating 515-1 receives the wavelengths λ.sub.1, λ.sub.2, λ.sub.3, reflects the wavelength λ.sub.1, and transmits the remaining wavelengths λ.sub.2, λ.sub.3. The mode multiplexer 520-1 receives the wavelength λ.sub.1 and provides the wavelength λ.sub.1 (with the mode converted to a fundamental mode) to the output port 525-1 as an optical signal 535-1.
(36) The grating 515-2 receives the wavelengths λ.sub.2, λ.sub.3, reflects the wavelength λ.sub.2, and transmits the remaining wavelength λ.sub.3. The mode multiplexer 520-2 receives the wavelength λ.sub.2 and provides the wavelength λ.sub.2 (with the mode converted to a fundamental mode) to the output port 525-2 as an optical signal 535-2. The remaining wavelength λ.sub.3 is provided from the grating 515-2 to the output port 525-3 as an optical signal 535-3.
(37) In the demultiplexer 505, the grating 515-2 represents a “last” grating in the cascaded arrangement of the gratings 515-0, 515-1, 515-2. Here, the grating 515-2 reflects a “second-to-last” wavelength (i.e., the wavelength λ.sub.2) of the plurality of wavelengths λ.sub.0, λ.sub.1, λ.sub.2, λ.sub.3 toward the output port 525-2, and transmits a “last” wavelength (i.e., the wavelength λ.sub.3) to the output port 525-3.
(38) In the diagram 600, the demultiplexer 605 comprises the input port 510, the plurality of output ports 525-0, 525-1, 525-2, 525-3, and a cascaded arrangement of the gratings 515-0, 515-1, 515-2 and a grating 515-3. The operation of the demultiplexer 605 is generally similar to that of the demultiplexer 505. However, the grating 515-3 receives the wavelength λ.sub.3 from the grating 515-2, and reflects the wavelength λ.sub.3. The demultiplexer 605 further comprises a mode multiplexer 520-3 that receives the wavelength λ.sub.3 and provides the wavelength λ.sub.3 (with the mode converted to a fundamental mode) to the output port 525-3 as the optical signal 535-3. In another embodiment, the mode multiplexer 520-3 may be omitted.
(39) In some embodiments, the output of the grating 515-3 (e.g., a transmit port) is coupled with an optical absorber 610. In some embodiments, the optical absorber 610 comprises a heavily-doped silicon waveguide. Beneficially, the optical absorber 610 mitigates reflections of optical signals, which can further improve the signal-to-noise ratio (SNR) of the optical signal 535-3.
(40) In the demultiplexer 605, the grating 515-3 represents a “last” grating in the cascaded arrangement of the gratings 515-0, 515-1, 515-2, 515-3. Here, the grating 515-3 reflects a “last” wavelength (i.e., the wavelength λ.sub.3) of the plurality of wavelengths λ.sub.0, λ.sub.1, λ.sub.2, λ.sub.3 toward the output port 525-3.
(47) FIG. 9 are graphs 900-0, 900-1, 900-2, 900-3 illustrating operation of the two-mode Bragg gratings as bandpass filters, according to one or more embodiments. The features illustrated in the graphs 900-0, 900-1, 900-2, 900-3 may be used in conjunction with other embodiments. For example, the cascaded arrangement in any of the demultiplexers 505, 605, 705, 805 may have gratings configured as bandpass filters. As discussed above, the gratings may have non-overlapping or partially overlapping passbands.
(48) In the graph 900-0, the first grating in the cascaded arrangement receives an optical signal comprising a plurality of signal components 905-0, 905-1, 905-2, 905-3 at a respective plurality of wavelengths λ.sub.0, λ.sub.1, λ.sub.2, λ.sub.3. A filter response 910-0 of the first grating includes a first passband 915-0, such that the signal component 905-0 (at the wavelength λ.sub.0) is reflected by the first grating. The remaining wavelengths λ.sub.1, λ.sub.2, λ.sub.3 (represented as a group 920-0 of the signal components 905-1, 905-2, 905-3) are transmitted by the first grating to a second grating in the cascaded arrangement.
(49) In the graph 900-1, the second grating receives the signal components 905-1, 905-2, 905-3 at the respective wavelengths λ.sub.1, λ.sub.2, λ.sub.3. A filter response 910-1 of the second grating includes a second passband 915-1, such that the signal component 905-1 (at the wavelength λ.sub.1) is reflected by the second grating. The remaining wavelengths λ.sub.2, λ.sub.3 (represented as a group 920-1 of the signal components 905-2, 905-3) are transmitted by the second grating to a third grating in the cascaded arrangement.
(50) In the graph 900-2, the third grating receives the signal components 905-2, 905-3 at the respective wavelengths λ.sub.2, λ.sub.3. A filter response 910-2 of the third grating includes a third passband 915-1, such that the signal component 905-2 (at the wavelength λ.sub.2) is reflected by the third grating. The remaining wavelength λ.sub.3 (represented as a group 920-2 of the signal component 905-3) is transmitted by the third grating.
(51) The signal component 905-3 (at the wavelength λ.sub.3) is illustrated in the graph 900-3. In some embodiments, the signal component 905-3 is transmitted by the third grating to an output port. In other embodiments, the signal components 905-3 is reflected by a fourth grating toward the output port. Although the graphs 900-0, 900-1, 900-2, 900-3 show one sequence of filtering the signal components 905-0, 905-1, 905-2, 905-3 using the cascaded arrangement, other embodiments may have alternate sequences of filtering the signal components 905-0, 905-1, 905-2, 905-3.
(52) FIG. 10 are graphs 1000-0, 1000-1, 1000-2, 1000-3 illustrating operation of the two-mode Bragg gratings as low-pass filters, according to one or more embodiments. The features illustrated in the graphs 1000-0, 1000-1, 1000-2, 1000-3 may be used in conjunction with other embodiments. For example, the cascaded arrangement in any of the demultiplexers 505, 605, 705, 805 may have gratings configured as low-pass filters.
(53) In the graph 1000-0, the first grating in the cascaded arrangement receives the optical signal comprising the plurality of signal components 905-0, 905-1, 905-2, 905-3. A filter response 1005-0 of the first grating includes a first passband 1010-0, such that the signal component 905-0 (at the wavelength λ.sub.0) is reflected by the first grating. The remaining wavelengths λ.sub.1, λ.sub.2, λ.sub.3 are transmitted by the first grating to a second grating in the cascaded arrangement.
(54) In the graph 1000-1, the second grating receives the signal components 905-1, 905-2, 905-3. A filter response 1005-1 of the second grating includes a second passband 1010-1, such that the signal component 905-1 (at the wavelength λ.sub.1) is reflected by the second grating. The remaining wavelengths λ.sub.2, λ.sub.3 are transmitted by the second grating to a third grating in the cascaded arrangement.
(55) In the graph 1000-2, the third grating receives the signal components 905-2, 905-3. A filter response 1005-2 of the third grating includes a third passband 1010-1, such that the signal component 905-2 (at the wavelength λ.sub.2) is reflected by the third grating. The remaining wavelength λ.sub.3 is transmitted by the third grating.
(56) The signal component 905-3 (at the wavelength λ.sub.3) is illustrated in the graph 1000-3. In some embodiments, the signal component 905-3 is transmitted by the third grating to an output port. In other embodiments, the signal components 905-3 is reflected by a fourth grating toward the output port.
(57) As shown, the passbands 1010-0, 1010-1, 1010-2, 1010-3 are all partially overlapping with each other. However, other embodiments may include different combinations of passbands, which may include some passbands that are non-overlapping. For example, the cascaded arrangement may include a combination of one or more gratings configured as low-pass filters and one or more gratings configured as bandpass filters. Further, gratings configured as high-pass filters are also contemplated, whether used in isolation or in combination with other types of filters.
(58) FIG. 11 is a graph 1100 illustrating operation of the two-mode Bragg gratings as bandpass filters having partially overlapping passbands, according to one or more embodiments. The features illustrated in the graph 1100 may be used in conjunction with other embodiments. For example, the cascaded arrangement in any of the demultiplexers 505, 605, 705, 805 may have gratings configured as bandpass filters.
(59) The graph 1100 illustrates the filter responses 910-0, 910-1, 910-2, 910-3 for the respective gratings. The filter responses 910-0, 910-1, 910-2, 910-3 include the partially overlapping passbands 915-0, 915-1, 915-2, 915-3. Each passband 915-0, 915-1, 915-2, 915-3 has a respective center wavelength λ.sub.C0, λ.sub.C1, λ.sub.C2, λ.sub.C3 and a respective upper roll-off wavelength λ.sub.R0, λ.sub.R1, λ.sub.R2, λ.sub.R3. The center wavelengths λ.sub.C0, λ.sub.C1, λ.sub.C2, λ.sub.C3 and the upper roll-off wavelengths λ.sub.R0, λ.sub.R1, λ.sub.R2, λ.sub.R3 are selected such that ranges 1105-0, 1105-1, 1105-2, 1105-3 surrounding the respective wavelengths λ.sub.0, λ.sub.1, λ.sub.2, λ.sub.3 are entirely included between the center wavelengths λ.sub.C0, λ.sub.C1, λ.sub.C2, λ.sub.C3 and the upper roll-off wavelengths λ.sub.R0, λ.sub.R1, λ.sub.R2, λ.sub.R3. Stated another way, a first grating is designed such that a range 1105-0 surrounding a first wavelength λ.sub.0 is entirely included between the center wavelength λ.sub.C0 and the upper roll-off wavelength λ.sub.R0, a second grating is designed such that a range 1105-1 surrounding a second wavelength λ.sub.1 is entirely included between the center wavelength λ.sub.C1 and the upper roll-off wavelength λ.sub.R1, and so forth. By accommodating the ranges 1105-0, 1105-1, 1105-2, 1105-3 in this manner, the partially overlapping passbands 915-0, 915-1, 915-2, 915-3 may be spaced closer together to have a greater amount of overlap while maintaining suitable selectivity of the gratings (i.e., to reflect one wavelength but not an adjacent wavelength) in the cascaded arrangement.
(60) In one non-limiting example of a CWDM scheme, four (4) lanes are defined such that the wavelength λ.sub.0=1271 nm, the wavelength λ.sub.1=1291 nm, the wavelength λ.sub.2=1311 nm, and the wavelength λ.sub.3=1331 nm. Each of the ranges 1105-0, 1105-1, 1105-2, 1105-3 is ±6.5 nm of the respective wavelength λ.sub.0, λ.sub.1, λ.sub.2, λ.sub.3, such that the range 1105-0 is 1264.5 nm to 1277.5 nm (corresponding to a total range of 13 nm), the range 1105-1 is 1284.5 nm to 1297.5 nm, the range 1105-2 is 1304.5 nm to 1317.5 nm, and the range 1105-3 is 1324.5 nm to 1337.5 nm.
(61) Assume that the center wavelength λ.sub.C0=1264 nm, the center wavelength λ.sub.C1=1284 nm, the center wavelength λ.sub.C2=1304 nm, and the center wavelength λ.sub.C3=1324 nm (corresponding to a channel spacing of 20 nm). As each of the gratings has a passband of 32 nm, the upper roll-off wavelength λ.sub.R0=1280 nm, the upper roll-off wavelength λ.sub.R1=1300 nm, the upper roll-off wavelength λ.sub.R2=1320 nm, and the upper roll-off wavelength λ.sub.R3=1340 nm.
(62) In this way, the range 1105-0 (1264.5 nm to 1277.5 nm) is entirely included between the center wavelength λ.sub.C0 (1264 nm) and the upper roll-off wavelength λ.sub.R0 (1280 nm) for the first grating, the range 1105-1 (1284.5 nm to 1297.5 nm) is entirely included between the center wavelength λ.sub.C1 (1284 nm) and the upper roll-off wavelength λ.sub.R1 (1300 nm) for the second grating, and so forth.
Consequently, in light of Ling’s disclosure of embodiments of cascaded contra-directional couplers, it would have been obvious to one of ordinary skill in the art to modify St-Yves’ contra-directional couplers to disclose a wavelength division multiplexed (WDM) system comprising: a bus waveguide for receiving a WDM signal that includes a plurality of wavelength signals, wherein the bus waveguide includes a plurality of bus-waveguide portions; and a plurality of contra-directional coupler (contra-DC) filters that is optically coupled with the bus waveguide, wherein each contra-DC filter of the plurality thereof is characterized by a different filter bandwidth and different drop signal that includes a drop wavelength, and wherein the plurality of contra-DC filters is arranged in a series along the bus waveguide such that the plurality of filter bandwidths are non-overlapping and the plurality of drop wavelengths changes monotonically along the series; wherein each contra-DC filter includes a grating element that is optically coupled with a different bus-waveguide portion of the plurality thereof, the grating element comprising a periodic arrangement of teeth and a grating waveguide that extends through the entire length of the grating element, the grating waveguide including a drop port; St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text; because the resultant configurations and methods would facilitate incorporating multiplexing schemes into integrated silicon photonic devices. Ling, column 1, lines 14-26 (“WDM schemes support multiple channels through a light-carrying medium, such as an optical waveguide or an optical fiber. WDM schemes are typically distinguished by the spacing between wavelengths. For example, a “normal” WDM system supports 2 channels spaced apart by 240 nanometers (nm), a coarse WDM (CWDM) system supports up to eighteen (18) channels that are spaced apart by 20 nm, and a dense WDM (DWDM) system supports up to eighty (80) channels that are spaced apart by 0.4 nm. Due to the wavelength spacing, a CWDM system tends to be more tolerant than a DWDM system and does not require high-precision controlled laser sources. As a result, a CWDM system tends to be less expensive and consumes less power.”) and column 3, lines 13-29 (“The optical apparatus comprises a plurality of transmitters 105-1, 105-2, 105-3, . . . , 105-M (generically, a transmitter 105) that provide optical signals via a respective plurality of optical links 110-1, 110-2, 110-3, . . . , 110-M (generically, an optical link 110) to a multiplexer 115. In some embodiments, each transmitter 105 comprises a laser source generating a respective optical signal (e.g., an unmodulated continuous wave (CW) optical signal) having a respective wavelength. The wavelengths of the optical signals may be selected according to a predefined multiplexing scheme, such as WDM, DWDM, or CWDM. Each transmitter 105 may further comprise an optical modulator configured to modulate the respective optical signal, and may further comprise circuitry for further processing of the respective optical signal. In some embodiments, the optical links 110 are optical waveguides formed in a silicon photonic chip. In other embodiments, the optical links 110 are optical fibers.”).
Regarding claims 2-19, it would have been obvious to one of ordinary skill in the art to modify St-Yves in view of Ling’s embodiments, as applied in the rejection of claim 1, to disclose:
2. The WDM system of claim 1 wherein the plurality of drop wavelengths increases monotonically along the series. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
3. The WDM system of claim 1 wherein a first contra-DC filter of the plurality thereof gives rise to a first reflected signal on the bus waveguide, and wherein the first reflected signal has a first reflected spectrum that is within the filter bandwidth of a second contra-DC filter of the plurality thereof, and further wherein the first and second contra-DC filters are adjacent in the series. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
4. The WDM system of claim 3 wherein the plurality of filter bandwidths collectively defines a composite bandwidth, and wherein each contra-DC filter of the plurality thereof gives rise to a second reflected signal on its respective grating waveguide, and further wherein each of the plurality of second reflected signals has a reflected spectrum that is outside the composite bandwidth. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
5. The WDM system of claim 3 wherein the first contra-DC filter of the plurality thereof gives rise to a second reflected signal on its respective grating waveguide, and wherein the second reflected signal has a second reflected spectrum that is between the filter bandwidth of the first contra-DC filter and the filter bandwidth of a second contra-DC filter that is adjacent to the first contra-DC filter in the series. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
6. The WDM system of claim 3 wherein each filter bandwidth of the plurality thereof includes a pad region, and wherein the first contra-DC filter of the plurality thereof gives rise to a second reflected signal on its respective grating waveguide, and wherein the second reflected signal has a second reflected spectrum that is within the pad region of a second contra-DC filter that is adjacent to the first contra-DC filter in the series. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
7. The WDM system of claim 1 wherein each contra-DC filter includes a different portion of the bus waveguide, and wherein, at each contra-DC filter of the plurality thereof, its respective bus-waveguide portion and grating element are configured to define first and second taper regions and a mirror region located between the first and second taper regions, the mirror region being a strongly coupled region for a first light signal, the grating waveguide being included in each of the first and second taper regions and the mirror region, and wherein the first taper region includes a first adiabatic coupler for adiabatically transitioning the first light signal between a first weak coupling region and the mirror region, and further wherein the second taper region includes a second adiabatic coupler for adiabatically transitioning a second light signal between the mirror region and a second weak coupling region, the second light signal including at least a portion of the first light signal. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
8. The WDM system of claim 7 wherein each bus-waveguide portion of the plurality thereof has a first core having a first width at an input port and a second width at the mirror region of its respective contra-DC filter, the first width being larger than the second width. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
9. The WDM system of claim 1 wherein each tooth of the periodic arrangement of teeth has a tooth length that varies according to its position within the periodic arrangement. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
10. The WDM system of claim 1 wherein at least one drop signal of the plurality thereof includes a wavelength channel that is a CWDM channel, and wherein the CWDM channel includes a plurality of DWDM signals. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
11. A method for dropping at least one wavelength signal from a wavelength divisional multiplexed (WDM) signal that includes a first plurality of wavelength signals, the method comprising: providing the WDM signal on a bus waveguide that is operatively coupled with a plurality of contra-directional coupler (contra-DC) filters, wherein each contra-DC filter of the plurality thereof is characterized by a different filter bandwidth and different drop signal that includes a drop wavelength, and wherein the plurality of contra-DC filters is arranged in a series along the bus waveguide such that the plurality of filter bandwidths are non-overlapping and the plurality of drop wavelengths changes monotonically along the series; dropping a first drop signal to a first drop port of a first contra-DC filter of the plurality thereof; and dropping a second drop signal at a second drop port of a second contra-DC filter of the plurality thereof. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
12. The method of claim 11 further comprising providing the plurality of contra-DC filters such that the plurality of drop wavelengths increases monotonically along the series. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
13. The method of claim 11 wherein the first contra-DC filter gives rise to a first reflected signal on the bus waveguide, the first reflected signal having a first reflected spectrum, and wherein the method further includes: providing the first and second contra-DC filters such that they are adjacent in the series, wherein the second contra-DC filter is provided such that its respective filter bandwidth includes the first reflected spectrum; and suppressing the first reflected signal at the second contra-DC filter. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
14. The method of claim 13 wherein the first contra-DC filter gives rise to a second reflected signal on its respective grating waveguide, the second reflected signal having a second reflected spectrum, and wherein the method further includes: providing the plurality of contra-DC filters such that the plurality of filter bandwidths defines a composite bandwidth that is non-inclusive of the second reflected spectrum. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
15. The method of claim 13 wherein the first contra-DC filter gives rise to a second reflected signal on its respective grating waveguide, the second reflected signal having a second reflected spectrum, and wherein the method further includes: providing the first and second contra-DC filters such that they are adjacent in the series and such that second reflected spectrum is between their respective filter bandwidths. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
16. The method of claim 13 wherein the first contra-DC filter gives rise to a second reflected signal on its respective grating waveguide, the second reflected signal having a second reflected spectrum, and wherein the method further includes: providing the plurality of contra-DC filters such that each filter bandwidth includes a pad region, wherein the pad region included in the filter spectrum of the second contra-DC filter includes the second reflected spectrum. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
17. The method of claim 11 wherein each contra-DC filter of the plurality thereof is provided such that it includes a different bus-waveguide portion of the bus waveguide, and wherein, at each contra-DC filter of the plurality thereof, its respective bus-waveguide portion and grating element are configured to define first and second taper regions and a mirror region located between the first and second taper regions, the mirror region being a strongly coupled region for a first light signal, the grating waveguide being included in each of the first and second taper regions and the mirror region, and wherein the first taper region includes a first adiabatic coupler for adiabatically transitioning the first light signal between a first weak coupling region and the mirror region, and further wherein the second taper region includes a second adiabatic coupler for adiabatically transitioning a second light signal between the mirror region and a second weak coupling region, the second light signal including at least a first portion of the first light signal. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
18. The method of claim 17 wherein each contra-DC filter of the plurality thereof is provided such that its respective bus-waveguide portion has a core having a first width at an input port and a second width at the mirror region of its respective contra-DC filter, the first width being larger than the second width. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
19. The method of claim 11 wherein at least one contra-DC filter of the plurality thereof is provided such that its respective drop signal includes a wavelength channel that is a CDWM channel, and wherein the CWDM channel includes a plurality of DWDM signals. St-Yves, figures 2.1, 2.2, 2.7, and 3.3, and related figures and text, for example, St-Yves – Selected Text; Ling, figures 5 and 8-10, and related figures and text, for example, Ling – Selected Text.
because the resultant configurations and methods would facilitate incorporating multiplexing schemes into integrated silicon photonic devices. Ling, column 1, lines 14-26 and column 3, lines 13-29.
Conclusion
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/PETER RADKOWSKI/Primary Examiner, Art Unit 2874