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 Comment – Independent Claim 1
As presented below, independent claim 1 is rejected under 35 U.S.C. 103 as being unpatentable over Tanigawa et al. (2013/0308913; “Tanigawa”) in view of Azendorf et al. (Group Delay Measurements of Multicore Fibers with Correlation Optical Time Domain Reflectometry, 2020 22nd International Conference on Transparent Optical Networks (ICTON), pp. 1-4; “Azendorf”) and further in view of Kingsta et al. (A review on coupled and uncoupled multicore fibers for future ultra-high capacity optical communication, Optik - International Journal for Light and Electron Optics 199 (2019) 163341; “Kingsta”).
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-20
Claims 1-20 are rejected under 35 U.S.C. 103 as being unpatentable over Tanigawa et al. (2013/0308913; “Tanigawa”) in view of Azendorf et al. (Group Delay Measurements of Multicore Fibers with Correlation Optical Time Domain Reflectometry, 2020 22nd International Conference on Transparent Optical Networks (ICTON), pp. 1-4; “Azendorf”) and further in view of Kingsta et al. (A review on coupled and uncoupled multicore fibers for future ultra-high capacity optical communication, Optik - International Journal for Light and Electron Optics 199 (2019) 163341; “Kingsta”).
Regarding claim 1, Tanigawa discloses in figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text, the cross-talk characteristics of multicore fiber embodiments 1 comprising: a cylindrical cladding 30 encapsulating a first core 11 located along the cladding’s central axis and secondary helically twisted cores 12 disposed about the first core; and protective layers 31 and 32. Tanigawa [0088] (“it is found that the multicore fiber according to the present invention can suppress variation in the amount of crosstalk between specific cores even when the multicore fiber is disposed in a bent state”) and [0089] (“as is clear from Table 1, when the pitch is time/m or more on average, the variation in crosstalk between the cores becomes substantially a little, and, when the pitch is 4 time/m or more on average, the variation becomes less”).
Tanigawa – Figures 1 and 2
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Tanigawa – Selected Text
[0034] FIG. 1 is a view illustrating a state of a multicore fiber according to an embodiment of the present invention, and, more specifically, FIG. 1A is a view illustrating a structure in a vertical cross-section of the multicore fiber in a longitudinal direction and FIG. 1B is a view illustrating a refractive index distribution in a B-B line in FIG. 1A. In addition, FIG. 1B illustrates the refractive index distribution when the multicore fiber is linear.
[0035] As illustrated in FIG. 1A, a multicore fiber 1 according to the embodiment has a plurality of cores 11 and 12, a clad 30 which entirely surrounds a plurality of cores 11 and 12 and fills between the respective cores 11 and 12, and which surrounds outer peripheral surfaces of the respective cores 11 and 12, an inner protective layer 31 which covers the outer peripheral surface of the clad 30 and an outer protective layer 32 which covers the outer peripheral surface of the inner protective layer 31.
[0036] With the embodiment, the number of cores is seven, and one core 11 is arranged in the center, and the other six cores 12 are arranged along the outer periphery of the clad 30 at equal intervals. Thus, the center core 11 and the respective outer periphery side cores 12 are arranged in a triangular grid. Hence, inter-center distances between the cores 11 and 12 are equal. A plurality of cores 11 and 12 arranged in this way are arranged symmetrically with respect to the center axis of the clad 30. That is, when the multicore fiber 1 is rotated at a predetermined angle around the center axis of the clad 30, the positions of the respective outer periphery side cores after rotation are the positions of the other outer periphery side cores 12 before rotation. Further, the core arranged in the center does not move even when the multicore fiber 1 is rotated around the center axis. The respective cores 11 and 12 are arranged at positions symmetrically with respect to the center axis of the clad 30, so that it is possible to make the optical property resulting from an arrangement of the respective cores 11 and 12 uniform.
[0037] Further, with the embodiment, diameters of the respective adjacent cores 11 and 12 are slightly different from each other. Although the size of each member forming this multicore fiber 1 is not limited in particular, the diameter of the core 11 arranged in the center is, for example, 6.9 .mu.m, the diameters of the cores 12 arranged on the outer periphery side are made different at, for example, about 3% with respect to the diameter of the core 11 arranged in the center, and the diameters of the adjacent cores 12 arranged in the outer periphery side are made different at, for example, about 0.5% to 5% from each other. Thus, even when the diameters of the adjacent cores 11 and 12 are physically slightly different, the diameters of the respective cores 11 and 12 are not substantially different for lights propagating in the cores 11 and 12 and virtually the same optical characteristics are provided, and the diameters of the adjacent cores 11 and 12 are physically slightly different, so that it is possible to suppress crosstalk between the adjacent cores 11 and 12. In this case, the difference between the diameters of the adjacent cores 11 and 12 is preferably 1% to 5% of the diameters from the view point of suppressing crosstalk and equalizing optical characteristics of the respective cores.
[0038] Further, the diameter of the clad 30 is, for example, 124 the outer diameter of the inner protective layer 31 is, for example, 190 .mu.m and the outer diameter of the outer protective layer 32 is, for example, 250 .mu.m. Furthermore, the inter-center distances between the respective cores 11 and 12 are not limited in particular, and are, for example, 37 .mu.m.
[0039] Still further, as illustrated in FIG. 1B, with the embodiment, a refractive index n.sub.1 of the core 11 arranged in the center and refractive indices n.sub.2 of the respective cores 12 arranged on the outer periphery side are higher than a refractive index n.sub.3 of the clad 30, and the refractive indices n.sub.2 of the respective cores 12 arranged on the outer periphery side are higher than the refractive index n.sub.1 of the core 11 arranged in the center. In addition, although the refractive indices of the adjacent cores 12 are preferably different among the cores 12 arranged on the outer periphery side from the view of point of suppressing crosstalk between the respective outer periphery side cores 12, the embodiment will be described for ease of understanding assuming that the refractive indices of the cores 12 arranged on the outer periphery side are equal as described above. In addition, the differences between the refractive indices of the adjacent cores 11 and 12 are preferably 1% to 5% of the refractive indices from the view point of suppressing crosstalk and equalizing the optical characteristics of the respective cores.
[0040] In addition, in FIG. 1B, refractive indices of the inner protective layer 31 and the outer protective layer 32 will not be described.
[0041] In the multicore fiber, materials of the cores 11 and 12 are, for example, silica glass doped with a dopant such as germanium which increases the refractive indices, and a material of the clad 30 is silica glass which is not doped with any dopant. Further, materials of the inner protective layer 31 and the outer protective layer 32 are ultraviolet curable resin.[0045] FIG. 2 is a view illustrating the state of the cores 11 and 12 of the multicore fiber 1 in FIG. 1. In addition, in FIG. 2, for ease of understanding, the clad 30 is shown by a broken line, the inner protective layer 31 and the outer protective layer 32 are not shown and scales of the multicore fiber 1 in the longitudinal direction and the diameter direction are changed from an actual multicore fiber.
[0046] As illustrated in FIG. 2, the center core 11 is arranged along the center of the axis of the clad 30, and the outer periphery side cores 12 are spirally arranged to rotate around the center axis of the clad 30 in the identical direction. In FIG. 2, the outer periphery side cores 12 are arranged to rotate rightward along a direction of an arrow A. That is, in the multicore fiber 1, the cores 12 are solidified in a state in which the cores 12 are formed in the spiral pattern, and the cores 12 are permanently twisted.
[0047] In addition, in FIG. 2, the spiral outer periphery side cores 12 rotate around the center axis of the clad 30 at the same pitch. That is, in all sections of the multicore fiber 1 in the longitudinal direction, the number of rotations of the cores 12 per unit length of the multicore fiber 1 is fixed.
[0048] However, in the multicore fiber 1, the spiral cores 12 have sections in which the pitch at which the cores 12 rotate around the center axis of the clad 30 changes. That is, the pitch of rotation of the spiral cores 12 may be 1 time/m in, for example, a given predetermined section and may be 0.5 time/m in another section, and, moreover, the cores 12 may rotate at another pitch in still another section. Further, the pitch of the spiral cores 12 may change at all sections.
[0049] Furthermore, although not illustrated in particular, the spiral cores 12 may repeat rightward rotation and leftward rotation around the center axis of the clad 30. That is, the spiral cores 12 may be arranged to rotate rightward in a predetermined section, and rotate leftward in a section adjacent to this predetermined section. Further, in this case, the cores 12 do not rotate around the center of the axis of the clad 30 between the section for rightward rotation and the section for leftward rotation of the cores 12, and may be arranged in parallel to the core 11. Furthermore, a length of each section for rightward rotation and a length of each section for leftward rotation of the spiral cores 12 may not be fixed.
[0050] Still further, the cores 12 preferably rotate around the center axis of the clad 30 at a pitch equal to or more than 1 time/m on average, and, more preferably, rotate at a pitch equal to or more than 4 time/m on average. In addition, when the cores 12 rotate in a right direction and a left direction, respectively, as described above, this pitch is calculated by adding the number of rotations in the right direction and the number of rotations in the left direction as positive values. When, for example, the spiral cores 12 rotate 0.5 times to the right around the center axis of the clad 30 in a section of 0.5 m of the multicore fiber 1 and then rotates 0.5 times to the left in a subsequent section of 0.5 m, the number of rotations per 1 m is 0.5+0.5=1 time and the pitch of the cores 12 in this case are 1 time/m.
[0088] Consequently, it is found that the multicore fiber according to the present invention can suppress variation in the amount of crosstalk between specific cores even when the multicore fiber is disposed in a bent state.
[0089] Further, as is clear from Table 1, when the pitch is time/m or more on average, the variation in crosstalk between the cores becomes substantially a little, and, when the pitch is 4 time/m or more on average, the variation becomes less.
Further regarding claim 1, while Tanigawa’s embodiments disclose correlations between pitch and crosstalk, Azendorf discloses in figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text, that propagation delay and polarization mode dispersion (PMD) characteristics of multicore fiber embodiments are related, in part, to symmetries/asymmetries and birefringence. Azendorf, Abstract (“the propagation delay in the cores depends on the position of the core in the fiber and that the differential delay between the cores varies with temperature”), 3.1 Group Delay Measurements (“The differential delay, or skew, of all cores was calculated with respect to the center core. In Fig. 3, as an example, the cross section of a 5-km, 19-core fiber is shown with the labels showing the skew of each core with respect to the center core #10…It can be seen that the skew between the cores depends on the position of the core in the fiber. One side of the fiber cross area experienced a higher delay than the opposite area.”), and 3.3 PMD measurements (“…The differential group delay (DGD) of the fiber cores was measured, using the MPS method for four different input states of polarization, as a function of wavelength over a spectral bandwidth of 110 nm. The PMD was calculated as the average value of the DGD. The results showed high PMD values (up to 22 ps) for either the edge cores or all cores of the multi-core fibers. The central core of all multicore fibers showed PMD values below 0.43 ps. We assume that these high PMD values are caused by birefringence, induced due to the nonsymmetric stress from neighbor cores. This assumption can be supported by the observation that the cores of the inner ring of the 5-km, 19-core fiber, with neighbors allocated symmetrically, showed low PMD, whereas the edge cores exhibited PMD values up to 6 ps. Figure 5 shows the core distribution of the 10-km, 7-core and the 5-km, 19-core fibers with the PMD values in ps for each core. In Fig. 5c, the average PMD values are shown for all fibers.”).
Azendorf – Figures 3 and 5
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Azendorf - Selected Text
ABSTRACT. Several multi-core fibers (MCF) were characterized using Correlation Optical Time Domain Reflectometry (C-OTDR) in terms of propagation delay and polarization mode dispersion (PMD). The results show that the propagation delay in the cores depends on the position of the core in the fiber and that the differential delay between the cores varies with temperature.
3. MULTI-CORE FIBER CHARACTERIZATION
3.1 Group delay measurements …The group delay of all cores of two 7-core fibers and two 19-core fibers from different vendors was characterized using the C-OTDR method. Four cores, including the center core, were simultaneously characterized and the results were referenced to the delay measured for the center core. This enabled a compensation for environmental fluctuations during the measurement. For comparison, the group delay was also characterized using the modulation phase shift (MPS) method, which only allowed the characterization of one core at a time. As only consecutive measurements were possible, delay variations of up to 300 ps were observed in comparison to the C-OTDR technique. The differential delay, or skew, of all cores was calculated with respect to the center core. In Fig. 3, as an example, the cross section of a 5-km, 19-core fiber is shown with the labels showing the skew of each core with respect to the center core #10.
It can be seen that the skew between the cores depends on the position of the core in the fiber. One side of the fiber cross area experienced a higher delay than the opposite area. We assume that this effect is caused by spooling of the fiber.
3.3 PMD measurements …The differential group delay (DGD) of the fiber cores was measured, using the MPS method for four different input states of polarization, as a function of wavelength over a spectral bandwidth of 110 nm. The PMD was calculated as the average value of the DGD. The results showed high PMD values (up to 22 ps) for either the edge cores or all cores of the multi-core fibers. The central core of all multicore fibers showed PMD values below 0.43 ps. We assume that these high PMD values are caused by birefringence, induced due to the nonsymmetric stress from neighbor cores. This assumption can be supported by the observation that the cores of the inner ring of the 5-km, 19-core fiber, with neighbors allocated symmetrically, showed low PMD, whereas the edge cores exhibited PMD values up to 6 ps. Figure 5 shows the core distribution of the 10-km, 7-core and the 5-km, 19-core fibers with the PMD values in ps for each core. In Fig. 5c, the average PMD values are shown for all fibers.
Consequently, in light of Azendorf’s disclosure of the relationship between (1) multicore geometries (number and distribution of cores) and asymmetries (stress and birefringence) and (2) group and differential delays, it would have been obvious to one of ordinary skill in the art to modify Tanigawa’s multicore embodiments to disclose: a central axis (z); a cladding extending along z, the cladding comprising a substantially circular axial cross section, the substantially circular axial cross section comprising a cladding center, the substantially circular axial cross section further comprising a cladding outer diameter (ODclad); a twist about z, the twist having a period (τ) that is less than 9.1 centimeters (τ<9.1 cm); a first core disposed within the cladding, the first core being disposed helically about z to form a helical core, the helical core comprising a helical pitch (p) that is approximately equal to τ (p≈τ); and a second core disposed within the cladding; cross-talk from cross-coupling between the first core and the second core, the cross-talk increasing under micro-bend conditions to a maximum amount of increased cross-talk, the maximum amount of increased cross-talk being limited by the twist; and a coating disposed about the cladding, the coating comprising a coating outer diameter (ODcoat); Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text; because the resulting configuration would facilitate designing, fabricating, and deploying multicore fibers characterized by reduced crosstalk. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text (“Inter-core crosstalk (XT) is one of the most important properties of uncoupled MCFs and is proportional to the power of the mode coupling coefficient. Minimization of core to core crosstalk is a major factor of concern for real time use of uncoupled MCFs … In C-MCF, supermodes have different propagation constants just like modes in standard multimode fibers, and therefore their superposition produces a different power distribution along the fiber making this as the main source of cross talk in MCFs …In addition, the cladding thickness, which is the distance from the centre of outermost core to the outer cladding edge in an MCF, should be large enough for reducing micro bending and macro bending losses in the cores which are situated at the outer circle…Thus it is evident that intercore crosstalk, fiber nonlinearity, and core density are mutually related with one another and a compromise always exists between them ….The target crosstalk level however depends on the modulation format to be used also …”).
Kingsta – Tables 1-4
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Kingsta – Selected Text
1. Introduction
In general, FM-MCF can be grouped into two types. One is uncoupled fiber where the center-to-center distance between neighboring cores, known as core pitch, is designed large enough to reduce mode coupling between cores. The other is coupled fiber with small core pitch thus allowing strong coupling of isolated modes between adjacent cores and non- adjacent cores, leading to the formation of supermodes [5,6]. Because field distribution of a coupled mode can be seen as a superposition of isolated modes of each individual core, the coupled modes are called as super-modes. The number of modes in a super-mode fiber is equivalent to the number of the cores times the number of modes in each core [7]. Fig. 2 shows the example images of FMF, uncoupled MCF (4 core) and coupled MCF (4 core).
2. Multicore fiber parameters
2.1. Space utilization efficiency
Table 1 shows some of the reported multicore fiber’s spatial channel count. The corresponding cladding diameter value and its coupling type also have been given in the table. It can be understood that for coupled MCF designs the cladding diameter was kept as 125 μm and the optimization is mainly done on the core pitch value to increase the channel count. On the other hand for uncoupled MCF designs the cladding diameter is increased even above 300 μm and hence SCC can be beyond 100. Each reported coupled and uncoupled MCF design was focused on different factors such as cross talk reduction, maximum achievable transmission distance, reduced differential mode delay, attenuation, receiver complexity and spectral efficiency.
2.2. Cross talk
Inter-core crosstalk (XT) is one of the most important properties of uncoupled MCFs and is proportional to the power of the mode coupling coefficient. Minimization of core to core crosstalk is a major factor of concern for real time use of uncoupled MCFs [17,27]. In C-MCF, supermodes have different propagation constants just like modes in standard multimode fibers, and therefore their superposition produces a different power distribution along the fiber making this as the main source of cross talk in MCFs
In addition, the cladding thickness, which is the distance from the centre of outermost core to the outer cladding edge in an MCF, should be large enough for reducing micro bending and macro bending losses in the cores which are situated at the outer circle [32]. Thus it is evident that intercore crosstalk, fiber nonlinearity, and core density are mutually related with one another and a compromise always exists between them ….The target crosstalk level however depends on the modulation format to be used also [13]. On the other hand, in the coupled MCFs, many cores are closely arranged in order to ensure strong mode coupling between each other [13]. Coupled mode theory indicates that mode coupling is usually caused by structural perturbations and imperfections such as microbending or core profile variation and is thus random in nature. Since the coupling of modes is strongly dependent on the fiber fabrication process, its influence on cross talk cannot be quantified at the stage of fiber design. In C-MCF, fiber twisting and bending have a considerable effect on the mode conversion between supermodes and hence mode coupling in C- MCF is greatly affected by the twist rate and bend radius of the MCF…
2.5. DMD
In MCF, the differential mode delay (DMD), defined as the variation in propagation delay caused by differences in group velocity among modes, differs depending on the core number and core arrangement. In coupled MCF, the DMD increases rapidly below a certain core distance, as the coupling coefficient increases. As coupling coefficient between higher order modes is larger than that between fundamental modes, DMD between higher order modes gives rise to the maximum DMD value. It had been suggested that, it is possible to design low DMD few mode MCFs by properly designing the core distance considering the coupling level of the higher order mode…
Although the heterogeneous core structure enables to design a MCF with a higher spatial density and without much increase in the inter core DMD, a slight deviation of the core refractive index profile design from the target may cause a rapid increase in inter core DMD. Hence core homogeneity, and in particular accurate refractive index control, is considered as an important factor for coupled MCFs in order to realize a low intercore DMD.
2.6. Receiver complexity
It has been found that strongly coupled MCF exhibits a unique impulse response characteristic which is similar to the polarization mode dispersion in single mode fiber such that the impulse response width increases in proportion to the square root of the fiber length. This characteristic is helpful for reducing the MIMO processing complexity particularly in long distance transmissions
Also the wavelength insensitivity of the MIMO DSP complexity with a single span transmission test has been proved for strongly coupled MCF. Compared to uncoupled MCF, with the coupled MCF it is possible to obtain lower and more wavelength flattened characteristics for the required tap number at MIMO equalizer and it reveals that strongly coupled MCF is an attractive transmission medium for wavelength division multiplexing MIMO systems in terms of reducing the MIMO DSP complexity
2.7. Recent progress
A strongly coupled four core MCF arranged in rectangular lattice was proposed in [78]. It is claimed that the rectangular arrangement of cores produces a strong birefringence between the degenerate modes and thus transmission with reduced cross talk and receiver complexity will be possible.
3. Conclusion
Development of various multi core fiber for SDM transmission provides a way to increase the capacity in both long haul and short reach optical networks. In this paper the design and characteristics of FM-MCF were analysed with respect to their coupling behaviour. Both coupled and uncoupled MCF received almost equal attention from the research community, having the common concern of enhancing per fiber capacity and spectral efficiency. From the view point of mode delay characteristics and nonlinear effects mitigation, coupled core fiber promises efficient transmission at high data rate but the compromise need to be done on receiver complexity. Also in coupled core fiber, increase in transmission impairments coincides with a square root pattern rather than a linear pattern. Mechanical reliability is also good as the cladding diameter is well around 125 μm. However many attempts are being taken in parallel to reduce cross talk, nonlinear effects and to increase capacity-distance product in uncoupled core fiber also. Increased core pitch and hence large cladding diameter is a major concern for the later case but the required receiver complexity is minimal. Irrespective of the coupling behaviour, both type of fibers need to exhibit transmission characteristics, especially attenuation, at least same as that of conventional SSMF.
As it can be observed from the previous discussions, the fiber which performs well in some characteristics (like SCC, fiber size, crosstalk, dispersion, SE, capacity, nonlinear effects and receiver side overhead etc.) lags in other factors. It will be more worthwhile to design a novel MCF by merging the design procedures used for coupled MCF and uncoupled MCF such that the merits of both coupled and uncoupled MCF are utilized properly. It is possible that, the MCF designed in this manner can preserve supermode characteristics within a group of few cores while reducing the overall MIMO based receiver complexity, which will be quite high if strong coupling is encouraged among all the cores in a MCF with complexity factor equal to(NM)2. Therefore, more efficient design optimization in terms of novel core profile design and core arrangement may yield simultaneous improvement in all aspects.
Regarding dependent claims 2-20, it would have been obvious to one of ordinary skill in the art to modify Tanigawa in view of Azendorf and further in view of Kingsta, as applied in the rejection of claim 1, to disclose:
2. The optical fiber of claim 1, wherein the second core is a central core extending substantially along z, the central core comprising a spin with a period of τ. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
3. The optical fiber of claim 1: wherein the first core is a first helical core; and wherein the second core is disposed helically about z to form a second helical core. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
4. The optical fiber of claim 1: wherein the first core comprises a maximum polarization mode dispersion (PMD) coefficient of 0.1 picoseconds-per-square-root-kilometer (ps/√km). Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
5. The optical fiber of claim 4, wherein the maximum PMD coefficient is 0.04 ps/√km. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
6. The optical fiber of claim 4, wherein the maximum PMD coefficient is 0.02 ps/√km. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
7. The optical fiber of claim 1: wherein the second core comprises a maximum polarization mode dispersion (PMD) coefficient of 0.1 picoseconds-per-square-root-kilometer (ps/√km). Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
8. The optical fiber of claim 7, wherein the maximum PMD coefficient is 0.04 ps/√km. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
9. The optical fiber of claim 7, wherein the maximum PMD coefficient is 0.02 ps/√km. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
10. The optical fiber of claim 1, wherein the maximum amount of increased cross-talk is limited to less than approximately ten decibels (˜10 dB) in a wavelength (λ) range of between approximately 1260 nanometers (nm) and 1360 nm (1260 nm<λ<1360 nm). Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
11. The optical fiber of claim 1, wherein the maximum amount of increased cross-talk is limited to less than approximately six decibels (˜6 dB) in a wavelength (λ) range of between approximately 1530 nanometers (nm) and 1565 nm (1530 nm<λ<1565 nm). Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
12. The optical fiber of claim 1, wherein ODclad is between approximately eighty (80) micrometers (μm) and approximately 300 μm (˜80 μm≤ODclad≤˜300 μm). Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
13. The optical fiber of claim 12, wherein ODclad is approximately equal to 125 μm (ODclad≈125 μm). Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
14. The optical fiber of claim 1, wherein ODcoat is between approximately 80 micrometers (μm) and approximately 700 μm (80 μm≤ODcoat≤700 μm). Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
15. The optical fiber of claim 14, wherein ODcoat≈245 μm. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
16. The optical fiber of claim 14, wherein ODcoat≈200 μm. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
17. The optical fiber of claim 1, wherein τ is greater than 2.5 cm (τ>2.5 cm). Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
18. The optical fiber of claim 17, wherein τ is between 2.9 cm and 6.7 cm (2.9 cm<τ<6.7 cm). Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
19. The optical fiber of claim 18, wherein 3.3 cm<τ<5.0 cm. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
20. The optical fiber of claim 19, wherein 3.4 cm<τ<4.0 cm. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text; Azendorf, figures 3 and 5, and related figures and text, for example, Azendorf – Selected Text; Tanigawa, figures 1 and 2, and related figures, tables, and text, for example, Tanigawa – Selected Text.
because the resulting configurations would facilitate designing, fabricating, and deploying multicore fibers characterized by reduced crosstalk. Kingsta, Tables 1-4, and related text, for example, Kingsta – Selected Text.
Conclusion
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/PETER RADKOWSKI/Primary Examiner, Art Unit 2874