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 .
Abstract
The abstract of the disclosure is objected to because it is over 150 words. A corrected abstract of the disclosure is required and must be presented on a separate sheet, apart from any other text. See MPEP § 608.01(b).
Claim Rejections – 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
1. Claims 1, 2, 6, & 7 are rejected under 35 U.S.C. 103 as being unpatentable over Matsushita (JP 2003188449 A), in view of Zhang (“Dual-wavelength random distributed feedback fiber laser with wavelength, linewidth, and power ratio tunability”)
2. Regarding Claim 1:
Matsushita teaches, an excitation light depolarizer suitable for Raman amplification, ([0006]: Figure 5 shows the relationship between the degree of power and PDG of Raman gain. From FIG. 5, it can be seen that the polarization dependence of the Raman gain can be eliminated by depolarizing the pumping light). Matsushita teaches a first multi-mode laser configured to output first pump light; a second multi-mode laser configured to output second pump light, a first pump current/temperature controller configured to control a temperature and a pump current of the first multi-mode laser; a second pump current/temperature controller configured to control a temperature and a pump current of the second multi-mode laser, wherein the first pump current/temperature controller and the second pump current/temperature controller control at least either pump currents or temperatures of the first multi-mode laser and the second multi-mode laser such that the longitudinal modes included in the first pump light and the longitudinal modes included in the second pump light do not overlap each other, ([0009]: By controlling the driving temperature of the LD and the driving current value of the LD, The two lights output from the LD do not interfere with each other in the depolarizer). Matsushita further teaches, ([0015]: A second embodiment of the depolarizer for pumping light using a polarization combiner with a depolarizer according to the present invention is that a polarization combiner with a depolarizer is provided on the output side of an LD, and the output light from the LD is polarized with a depolarizer. In a depolarizing device that synthesizes light by a wave combiner and depolarizes it into excitation light, in order to prevent the longitudinal modes of Fabry-Perot of the two LDs from overlapping in the spectrum of the high power region, either or both of the two LDs The drive temperature can be controlled). Matsushita teaches a polarization multiplexing circuit configured to polarization-multiplex, ([0004]: To increase the pumping light and depolarize the pumping light to eliminate the PDG, the polarization combiner (PBC) is used to remove the light of the same wavelength or different wavelengths output from the two LDs). See figures 2 & 7.
Matsushita does not teach a first polarization maintaining variable optical attenuator configured to receive the first pump light as an input, adjusts a light intensity of the first pump light while keeping a polarization state of the first pump light in a linearly polarized wave and outputs the first pump light; a second polarization maintaining variable optical attenuator configured to receive the second pump light as an input, adjusts a light intensity of the second pump light while keeping a polarization state of the second pump light in a linearly polarized wave, and outputs the second pump light; and a polarization multiplexing circuit configured to polarization-multiplex and outputs the first pump light with the light intensity adjusted by the first polarization maintaining variable optical attenuator and the second pump light with the light intensity adjusted by the second polarization maintaining variable optical attenuator, and the first polarization maintaining variable optical attenuator and the second polarization maintaining variable optical attenuator perform control such that intensities of the first pump light and the second pump light are equal to each other.
However, Zhang teaches, ([Fig. 1]: Shows 2 laser line sources, each coupled to a polarization maintaining variable optical attenuator which couple to a polarization maintaining coupler). Zhang further teaches, ([Abstract]: The power ratio of each laser line can be tuned from 0 to nearly 100% with the help of two variable optical attenuators).
It has been held that, in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists, see MPEP 2144.05 I.
One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita with Zhang to include the first polarization maintaining variable optical attenuator and the second polarization maintaining variable optical attenuator to perform control such that intensities of the first pump light and the second pump light are equal to each other, since such a configuration results in a perfectly balanced orthogonal source. This ensures uniform amplification across all signal polarization states, effectively eliminating or significantly reducing PDG. In addition, such a configuration ensures that the light remains strictly within its designated linear polarization axis, regardless of how much the intensity is attenuated and allows the control system to actively compensate for any imbalances or degradation in the pump laser diodes over time without disturbing the critical orthogonal alignment required by the multiplexing circuit. Maintaining the desired polarization state, regardless of attenuation, also provides maximum coupling efficiency and an exceptionally stable output power profile.
3. Regarding Claim 2:
Matsushita as modified by Zhang teaches the first pump current/temperature controller and the second pump current/temperature controller control at least either the pump currents or the temperatures of the first multi-mode laser and the second multi-mode laser such that the longitudinal modes included in the first pump light and the longitudinal modes included in the second pump light do not overlap each other and the first pump light has higher power than the second pump light.
See Claim 1.
It has been held that, in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists, see MPEP 2144.05 I.
One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita with Zhang to include the first pump light has higher power than the second pump light, since such a configuration results in an engineered asymmetry. This specific offset suppresses the gain fluctuations caused by the interaction of perfectly symmetrical pumps. It provides a finer degree of freedom to optimize noise figures and stabilize the amplification process against dynamic variations in the network.
4. Regarding Claim 6:
Matsushita does not explicitly teach, in a case where one arbitrary light frequency of longitudinal modes included in the first pump light is defined as a difference in light frequencies from a longitudinal mode that is smaller than f1_n and is the closest to f1_n from among the longitudinal modes included in the second pump light is defined as Δf1-, and a difference in light frequencies from a longitudinal mode that is greater than f1_n and is the closest to f1_n from among the longitudinal modes included in the second pump light is defined as Δf1+, the first pump current/temperature controller sets at least either the pump current or the temperature of the first multi-mode laser to minimize the number of combinations that satisfy I Δf11+I = I Δf1-I, and in a case where one arbitrary light frequency of the longitudinal modes included in the second pump light is defined as f2_n, a difference in light frequencies from a longitudinal mode that is smaller than f2_n and is the closest to f2_n from among the longitudinal modes included in the first pump light is defined as Δf2-, and a difference in light frequencies from a longitudinal mode that is greater than f2_n and is the closest to f2_n from among the longitudinal modes included in the second pump light is defined as Δf2+ the second pump current/temperature controller sets at least either the pump current or the temperature of the second multi-mode laser to minimize the number of combinations that satisfy I Δf2+| = I Δf2-I.
However, Matsushita does teach, the first pump current/temperature controller and the second pump current/temperature controller control at least either pump currents or temperatures of the first multi-mode laser and the second multi-mode laser such that the longitudinal modes included in the first pump light and the longitudinal modes included in the second pump light do not overlap each other. See Claim 1.
Matsushita further teaches the frequency spectrum of the pump lights are tuneable over a range, overlapping the range in claim 6, ([Fig. 3]: Shows a spectrum change in a longitudinal mode of Fabry-Perot when the driving temperature of the LD is changed).
It has been held that, in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists, see MPEP 2144.05 I.
One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita to include the first pump current/temperature controller sets at least either the pump current or the temperature of the first multi-mode laser to minimize the number of combinations that satisfy I Δf11+I = I Δf1-I and the second pump current/temperature controller sets at least either the pump current or the temperature of the second multi-mode laser to minimize the number of combinations that satisfy I Δf2+| = I Δf2-I, since pump intensity fluctuations (RIN) transfer directly and quasi-instantaneously to co-propagating communication signal channels due to the small group velocity mismatch, breaking the frequency spacing symmetry spreads out and suppresses low-frequency intensity beat notes, lowering the overall RIN transfer into the signal's modulation band. In addition, by dynamically controlling the laser diode injection current or thermoelectric cooler (TEC) temperature, the optical cavity length and refractive index shift slightly. This shifts the longitudinal mode comb enough to eliminate exact mid-point coincidences across the spectrum, significantly flattening the pump noise profile and enhancing the optical signal-to-noise ratio (OSNR) of the transmission lines.
5. Regarding Claim 7:
Matsushita does not explicitly teach, a constant that is defined in advance to be greater than 0 and smaller than 1 is defined as R, I Δf1+I=I Δf1-I is allowed in relation to the longitudinal modes having intensities of equal to or less than P1_max * R when a longitudinal mode with the maximum optical power in the first pump light is defined as P1_max and I Δf2+I=I Δf2-I is allowed in relation to the longitudinal modes having intensities of equal to or less than P2_max * R when the longitudinal mode having the maximum optical power in the second pump light is defined as P2_max.
However, Zhang teaches, ([P. 10520, Chapter 3.3]: As shown in Fig. 5, the power ratio between the two Stokes lines can be tuned from 33.83 dB to 26.27 dB, which could be limited by the spontaneous Raman noise. Correspondingly, the power ratio of each Stokes lines can be tuned continuously from 0 to nearly 100%).
It has been held that, in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists, see MPEP 2144.05 I.
One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita with Zhang to include a constant that is defined in advance to be greater than 0 and smaller than 1 is defined as R, I Δf1+I=I Δf1-I is allowed in relation to the longitudinal modes having intensities of equal to or less than P1_max * R when a longitudinal mode with the maximum optical power in the first pump light is defined as P1_max and I Δf2+I=I Δf2-I is allowed in relation to the longitudinal modes having intensities of equal to or less than P2_max * R when the longitudinal mode having the maximum optical power in the second pump light is defined as P2_max, since such a configuration ensures highly symmetric, stable, and balanced gain profiles while minimizing multi-channel crosstalk and noise. Setting a threshold fraction focuses the structural symmetry requirement on the core energy envelope of the pumps. Ensuring that the frequency distribution of the side modes behaves identically on both sides of the peak frequency ensures that the power transfer from the pumps to the signal channels is perfectly balanced. This minimizes ripples in the gain spectrum, providing a flat amplification gain across all communication channels.
6. Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Matsushita (JP 2003188449 A), in view of Zhang (“Dual-wavelength random distributed feedback fiber laser with wavelength, linewidth, and power ratio tunability”), as applied to Claim 1 above, and further in view of Kinoshita (EP 0734105 A2).
7. Regarding Claim 4:
Matsushita as modified by Zhang does not teach, a first isolator configured to block an input of reflected light is arranged at an output of the first multi-mode laser, and a second isolator configured to block an input of reflected light is arranged at an output of the second multi-mode laser.
However, Kinoshita teaches, ([Fig. 48]: Shows a first isolator and a second isolator configured to block an input of reflected light arranged at the output of a first and second pump source).
It would have been obvious for one of ordinary skill in the art before the effective filing date to modify Matsushita and Zhang with Kinoshita to include a first isolator configured to block an input of reflected light is arranged at an output of the first multi-mode laser, and a second isolator configured to block an input of reflected light is arranged at an output of the second multi-mode laser, since it is the same field of endeavor and results would have been predictable. One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita and Zhang with Kinoshita, since such a configuration prevents optical feedback, ensures wavelength stability, suppresses cross-talk and channel interference, and maintains high-speed data integrity.
8. Claim 5 is rejected under 35 U.S.C. 103 as being unpatentable over Matsushita (JP 2003188449 A), in view of Zhang (“Dual-wavelength random distributed feedback fiber laser with wavelength, linewidth, and power ratio tunability”), as applied to Claim 1 above, as evidenced by RP Photonics.
9. Regarding Claim 5:
Matsushita teaches, a first polarizer configured to transmit a single linearly polarized wave is arranged at an output of the first multi-mode laser, and a second polarizer configured to transmit a single linearly polarized wave is arranged at an output of the second multi-mode laser, ([0003]: For example, when the polarization of the pumping light is linearly polarized (usually, the laser light emitted from the LD is linearly polarized)). Matsushita further teaches, ([Fig. 1]: Shows each LD connected to a polarization combiner (PBC) which acts as a polarizer for each input axis). As evidenced by RP Photonics, (Polarization Beam Combining]: Polarization beam combining (or polarization coupling) is a simple technique for combining (superimposing) two linearly polarized laser beams. For example, the output beams of two broad area laser diodes, one being vertically polarized and the other one horizontally polarized, can be sent onto a thin-film polarizer such that one of the beams is reflected, the other one transmitted, and both beams then propagate in the same direction. As a result, one obtains an unpolarized beam having the combined optical power of the input beams (disregarding some parasitic losses) and the same beam quality. Accordingly, the brightness is nearly doubled. This technique is often used e.g. for end pumping of a solid-state laser with an increased power. It works only if the laser crystal can similarly well absorb pump radiation with both polarization directions. This is the case e.g. for Nd:YAG). Thus, it is well known in the art that a polarization combiner is used to combine orthogonal polarization states. It is also understood that such combiners will act to linearly polarize light according to the polarization orientation of each input arm. In this way, the PBC also acts as a polarizer for each input axis.
10. Claim 3 is rejected under 35 U.S.C. 103 as being unpatentable over Matsushita (JP 2003188449 A), in view of Zhang (“Dual-wavelength random distributed feedback fiber laser with wavelength, linewidth, and power ratio tunability”), as applied to Claim 1 above, and further in view of Sun (“All-fiber polarization-maintaining erbium-doped dispersion-managed fiber laser based on a nonlinear amplifying loop mirror”).
11. Regarding Claim 3:
Matsushita as modified by Zhang teaches, a first multi-mode laser configured to output first pump light; a second multi-mode laser configured to output second pump light; a first pump current/temperature controller configured to control a temperature and a pump current of the first multi-mode laser; a second pump current/temperature controller configured to control a temperature and a pump current of the second multi-mode laser; and a polarization multiplexing circuit configured to polarization-multiplex
wherein the first pump current/temperature controller and the second pump current/temperature controller control at least either pump currents or temperatures of the first multi-mode laser and the second multi-mode laser such that longitudinal modes included in the first pump light and longitudinal modes included in the second pump light do not overlap each other. See Claim 1.
Matsushita as modified by Zhang does not teach, a first polarization maintaining optical amplifier configured to receive the first pump light as an input, amplifies a light intensity of the first pump light while keeping a polarization state of the first pump light in a linearly polarized wave, and outputs the first pump light; a second polarization maintaining optical amplifier configured to receive the second pump light as an input, amplifies a light intensity of the second pump light while keeping a polarization state of the second pump light in a linearly polarized wave, and outputs the second pump light
and outputs the first pump light with the light intensity amplified by the first polarization maintaining optical amplifier and the second pump light with the light intensity amplified by the second polarization maintaining optical amplifier, and the first polarization maintaining optical amplifier and the second polarization maintaining optical amplifier perform control such that the intensities of the first pump light and the second pump light are equal to each other.
However, Sun teaches, ([Fig. 1]: Shows 2 pump sources, each connected to a polarization maintaining optical amplifier). Sun further teaches, ([P.1493, Chapter 2]: The experimental setup of the all-PM erbium-doped fiber oscillator operating at the DM regime is shown in Fig. 1). Sun goes on to teach, ([Fig. 2]: Shows the power of the pumps in each loop can be tuned over a range where the power of the first and second pump are equal).
It would have been obvious for one of ordinary skill in the art before the effective filing date to modify Matsushita and Zhang with Sun to include a first polarization maintaining optical amplifier configured to receive the first pump light as an input, amplifies a light intensity of the first pump light while keeping a polarization state of the first pump light in a linearly polarized wave, and outputs the first pump light; a second polarization maintaining optical amplifier configured to receive the second pump light as an input, amplifies a light intensity of the second pump light while keeping a polarization state of the second pump light in a linearly polarized wave, and outputs the second pump light and outputs the first pump light with the light intensity amplified by the first polarization maintaining optical amplifier and the second pump light with the light intensity amplified by the second polarization maintaining optical amplifier, and the first polarization maintaining optical amplifier and the second polarization maintaining optical amplifier perform control such that the intensities of the first pump light and the second pump light are equal to each other., since it is the same field of endeavor and results would have been predictable. One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita and Zhang with Sun, since such a configuration provides polarization-independent optical amplification (minimizing Polarization-Dependent Gain, or PDG) alongside high output power and stable gain balance. In addition such configurations provide orthogonal pump multiplexing, signal polarization insensitivity, clean state preservation, independent gain control, and beat-noise and fluctuation reduction.
12. Claims 8, 10, & 11 rejected under 35 U.S.C. 103 as being unpatentable over Matsushita (JP 2003188449 A), in view of Zhang (“Dual-wavelength random distributed feedback fiber laser with wavelength, linewidth, and power ratio tunability”) and Sun (“All-fiber polarization-maintaining erbium-doped dispersion-managed fiber laser based on a nonlinear amplifying loop mirror”), as applied to Claim 3 above, and further in view of Ackerman (US 20010036004 A1).
13. Regarding Claim 8:
Matsushita as modified by Zhang teaches, a first multi-mode laser configured to output first pump light with longitudinal mode frequency intervals of δf1; a second multi-mode laser configured to output second pump light with longitudinal mode frequency intervals of δf2; a first pump current/temperature controller configured to control a temperature and a pump current of the first multi-mode laser; a second pump current/temperature controller configured to control a temperature and a pump current of the second multi-mode laser; a polarization multiplexing circuit configured to polarization-multiplex and outputs the first pump light and the second pump light; wherein the first pump current/temperature controller and the second pump current/temperature controller control at least either pump currents or temperatures of the first multi-mode laser and the second multi-mode laser such that longitudinal modes included in the first pump light and longitudinal modes included in the second pump light do not overlap each other. See Claim 1.
Matsushita as modified by Zhang does not explicitly teach, in a case where the optical signal amplified by the first pump light and the second pump light is a digital signal of a baud rate fB, the frequency intervals and of the longitudinal modes are greater than the baud rate fB.
However Ackerman teaches, ([0016]: In accordance with the present invention, an optimized Raman pump source is utilized that produces at least 50 mW of output power, sufficient spectral width to suppress SBS, and is configured such that the frequency difference between all intense longitudinal pump modes (regardless of polarization) are separated by at least the electrical bandwidth of the communication system, or at least the walk-off frequency, where "walk-off frequency" is defined as the lowest frequency at which the pump-signal crosstalk is no longer a significant factor in degrading the performance of the Raman amplifier).
It would have been obvious for one of ordinary skill in the art before the effective filing date to modify Matsushita and Zhang with Ackerman to include in a case where the optical signal amplified by the first pump light and the second pump light is a digital signal of a baud rate fB, the frequency intervals and of the longitudinal modes are greater than the baud rate fB, since it is the same field of endeavor and results would have been predictable. One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita and Zhang with Ackerman, since (Ackerman: [0002]: The present invention relates to a Raman amplified optical communication system and, more particularly, to an optical communication system utilizing co-propagating Raman amplification with Raman pump sources particularly designed to overcome known pump-signal crosstalk problems).
Matsushita as modified by Zhang and Ackerman does not explicitly teach a gain medium, to which all of an optical signal and the first pump light and the second pump light output from the polarization multiplexing circuit are input, the gain medium amplifying and then outputting the optical signal.
However, Sun teaches, ([Fig. 1]: Shows a gain medium, to which all of an optical signal and the first pump light and the second pump light output from the polarization multiplexing circuit are input, the gain medium amplifying and then outputting the optical signal). Sun further teaches, ([P.1492, Introduction]: Driven by a diverse range of applications, such as frequency comb spectroscopy [1], optical communication, microscopy [2], and precision metrology [3], research on mode-locked ultrafast fiber lasers [4,5] has undergone an explosive growth in the past few years. Much effort has been put into maximizing the output pulse energy and minimizing pulse duration, without sacrificing the environmental robustness of the cavity design). Sun goes on to teach ([P. 1494, Chapter 2]: By adjusting the pump powers as 500 mW coupled into the main loop and 300mWcoupled into the NALM loop, the laser
is mode locked with a 3-dB bandwidth of 15 nm centered at 1550 nm, which is shown in Fig. 2. The optical signal-to-noise ratio is measured to be more than 40 dB).
It would have been obvious for one of ordinary skill in the art before the effective filing date to modify Matsushita, Zhang, and Ackerman with Sun to include a gain medium, to which all of an optical signal and the first pump light and the second pump light output from the polarization multiplexing circuit are input, the gain medium amplifying and then outputting the optical signal, since it is the same field of endeavor and results would have been predictable. One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita, Zhang, and Ackerman with Sun, since such a configuration can reduce or eliminate PDG, double the pump power via a single gain medium, reduce insertion loss and reduce the number of required components, simplifying the system architecture.
14. Regarding Claim 10:
Matsushita does not explicitly teach, in a case where one arbitrary light frequency of longitudinal modes included in the first pump light is defined as a difference in light frequencies from a longitudinal mode that is smaller than f1_n and is the closest to f1_n from among the longitudinal modes included in the second pump light is defined as Δf1-, and a difference in light frequencies from a longitudinal mode that is greater than f1_n and is the closest to f1_n from among the longitudinal modes included in the second pump light is defined as Δf1+, the first pump current/temperature controller sets at least either the pump current or the temperature of the first multi-mode laser to minimize the number of combinations that satisfy I Δf11+I = I Δf1-I, and in a case where one arbitrary light frequency of the longitudinal modes included in the second pump light is defined as f2_n, a difference in light frequencies from a longitudinal mode that is smaller than f2_n and is the closest to f2_n from among the longitudinal modes included in the first pump light is defined as Δf2-, and a difference in light frequencies from a longitudinal mode that is greater than f2_n and is the closest to f2_n from among the longitudinal modes included in the second pump light is defined as Δf2+ the second pump current/temperature controller sets at least either the pump current or the temperature of the second multi-mode laser to minimize the number of combinations that satisfy I Δf2+| = I Δf2-I.
However, Matsushita does teach, the first pump current/temperature controller and the second pump current/temperature controller control at least either pump currents or temperatures of the first multi-mode laser and the second multi-mode laser such that the longitudinal modes included in the first pump light and the longitudinal modes included in the second pump light do not overlap each other. See Claim 1.
Matsushita further teaches the frequency spectrum of the pump lights are tuneable over a range, overlapping the range in claim 10, ([Fig. 3]: Shows a spectrum change in a longitudinal mode of Fabry-Perot when the driving temperature of the LD is changed).
It has been held that, in the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists, see MPEP 2144.05 I.
One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita to include the first pump current/temperature controller sets at least either the pump current or the temperature of the first multi-mode laser to minimize the number of combinations that satisfy I Δf11+I = I Δf1-I and the second pump current/temperature controller sets at least either the pump current or the temperature of the second multi-mode laser to minimize the number of combinations that satisfy I Δf2+| = I Δf2-I, since pump intensity fluctuations (RIN) transfer directly and quasi-instantaneously to co-propagating communication signal channels due to the small group velocity mismatch, breaking the frequency spacing symmetry spreads out and suppresses low-frequency intensity beat notes, lowering the overall RIN transfer into the signal's modulation band. In addition, by dynamically controlling the laser diode injection current or thermoelectric cooler (TEC) temperature, the optical cavity length and refractive index shift slightly. This shifts the longitudinal mode comb enough to eliminate exact mid-point coincidences across the spectrum, significantly flattening the pump noise profile and enhancing the optical signal-to-noise ratio (OSNR) of the transmission lines.
15. Regarding Claim 11:
Matsushita as modified by Zhang, and Sun does not teach in a case where the optical signal is a digital signal with a baud rate fB, the differences Δf1+ ,Δf1-, Δf2+ and Δf2- of the light frequencies are greater than the baud rate fB.
However, Ackerman teaches, ([0016]: In accordance with the present invention, an optimized Raman pump source is utilized that produces at least 50 mW of output power, sufficient spectral width to suppress SBS, and is configured such that the frequency difference between all intense longitudinal pump modes (regardless of polarization) are separated by at least the electrical bandwidth of the communication system, or at least the walk-off frequency, where "walk-off frequency" is defined as the lowest frequency at which the pump-signal crosstalk is no longer a significant factor in degrading the performance of the Raman amplifier).
It would have been obvious for one of ordinary skill in the art before the effective filing date to modify Matsushita, Zhang, and Sun with Ackerman to include in a case where the optical signal is a digital signal with a baud rate fB, the differences Δf1+ ,Δf1-, Δf2+ and Δf2- of the light frequencies are greater than the baud rate fB, since it is the same field of endeavor and results would have been predictable. One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita, Zhang, and Sun with Ackerman, since (Ackerman: [0002]: The present invention relates to a Raman amplified optical communication system and, more particularly, to an optical communication system utilizing co-propagating Raman amplification with Raman pump sources particularly designed to overcome known pump-signal crosstalk problems).
16. Claims 9 & 12 are rejected under 35 U.S.C. 103 as being unpatentable over Matsushita (JP 2003188449 A), in view of Zhang (“Dual-wavelength random distributed feedback fiber laser with wavelength, linewidth, and power ratio tunability”), Sun (“All-fiber polarization-maintaining erbium-doped dispersion-managed fiber laser based on a nonlinear amplifying loop mirror”), and Ackerman (US 20010036004 A1), as applied to Claims 8 & 10 above, and further in view of Hainberger (US 20050152025 A1). .
17. Regarding Claim 9:
Matsushita as modified by Zhang, Ackerman, and Sun does not teach, the optical signal is a wavelength multiplexed signal with adjacent wavelength channel light frequency intervals of fWDM, and the longitudinal mode frequency intervals and δf1 and δf2 are values that are different from the adjacent wavelength channel light frequency intervals fWDM.
However, Hainberger teaches, ([0070]: In the following, the preferred embodiments for a certain number of Raman pumps will be disclosed. Note that a depolarized pump consist of two orthogonal waves of slightly different frequencies fp1 = fp- δδ f p and fp2 = f p+ δ fp. Thus, the FWM products of depolarized pumps are located in the frequency interval [f4-δf1-δf2 - δf3, f4+δf1+δf2+ δf3] where 2δf1, 2δf2, and 2δf3 are the frequency separations between the orthogonal waves of each depolarized pump. For the sake of simplicity depolarized pumps will be referred to as "pumps" in the following description. The spectral allocation of waves will be specified in terms of frequencies (f) as well as in terms of wavelengths (λ)).
It would have been obvious for one of ordinary skill in the art before the effective filing date to modify Matsushita, Zhang, Ackerman, and Sun with Hainberger to include the optical signal is a wavelength multiplexed signal with adjacent wavelength channel light frequency intervals of fWDM, and the longitudinal mode frequency intervals and δf1 and δf2 are values that are different from the adjacent wavelength channel light frequency intervals fWDM, since it is the same field of endeavor and results would have been predictable. One of ordinary skill in the art before the effective filing date would have been motivated to modify Matsushita, Zhang, Ackerman, and Sun with Hainberger, since, (Hainberger: [0069]: FWM among Raman pumps can be reduced by wavelength interleaved bi-directional Raman pumping as shown in FIG. 9 since the number of possible combinations of co-propagating pumps is reduced).
In addition, (Hainberger: [0110]: According to the present invention, FWM among Raman pumps is completely eliminated or considerably reduced in the signal wavelength region in an optical communication system employing Raman amplification).
18. Regarding Claim 12:
Matsushita as modified by Zhang, Ackerman, and Sun does not teach all the differences Δf1+ ,Δf1-, Δf2+ and Δf2- of the light frequencies are values that are different from the adjacent wavelength channel light frequency intervals fWDM.
However, Hainberger teaches this. See Claim 9.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 20010008459 A1: Discloses an optical amplifier for use in optical communications.
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/J.W.N./Examiner, Art Unit 3645
/JAMES R HULKA/Primary Examiner, Art Unit 3645
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