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Extremely Narrow Channel Spacing 10Gb/s-DWDM Transmission for - - PowerPoint PPT Presentation
Extremely Narrow Channel Spacing 10Gb/s-DWDM Transmission for - - PowerPoint PPT Presentation
SubOptic2010 Poster Session: System Design & Applications - SD14 Extremely Narrow Channel Spacing 10Gb/s-DWDM Transmission for Advanced Submarine Cable System Takehiro Nakano, Taketo Onuma, Takanori Inoue, Yoshihisa Inada, Takaaki
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Extremely Narrow Channel Spacing
▐ Figure1 shows the optical spectrum of the commercial modulation formats of 10Gb/s.
▐ Their spectrum widths are approximately 20~25GHz.
▐ We have confirmed the possibility of reducing the channel spacing
- f
10Gb/s signals down to 25GHz as shown in Figure2.
RZ RZ-DPSK NRZ
Vertical axis:10dB/div, Horizontal axis: 25GHz/div
Figure 1: Optical Spectra of 10Gb/s signals Figure 2: Channel spacing of 10Gb/s signals 33GH-spacing 25GH-spacing
Modulation formats : RZ-DPSK
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Receiver Sensitivity of 25GHz-spaced 10Gb/s signal
8 9 10 11 12 13 14 15 16 17 18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 OSNR [dB] Q value [dB]
Back-to-back Performance
RZ (25GHz-spacing) RZ (33GHz-spacing) RZ-DPSK (33GHz-spacing) RZ-DPSK (25GHz-spacing)
3dB
▐ In order to confirm the Q performance with narrow channel spacing
- f 25GHz, we compared the difference of receiver sensitivity
between the RZ-DPSK signal and the RZ signal with 25GHz and 33GHz channel spacing . This result indicates that the RZ-DPSK signal keeps its excellent receiver sensitivity with 25GHz channel spacing.
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Assessment of Transmission Performance
▐ A narrow channel spacing enhances the nonlinear effects, such as the cross-phase modulation (XPM) and the four-wave- mixing (FWM), in the optical fiber transmission, and it degrades the transmission performances. ▐ To make an assessment of the transmission performance with a narrow channel spacing, we compared the Q values between 25GHz and 33GHz channel spacing after long distance transmission over the dispersion managed fiber (DMF).
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(1) Experimental Setup
▐ To make an assessment, we prepared long distance transmission line with the re-circulating technique and RZ-DPSK signals of 25GHz and 33GHz channel spacing .
LD1 LD2 LD3 LD4 LD7 LD8 RZ-DPSK Transmitter (Even) 41CW Lights DCF SW1 SW2
DMF1075km Transmission Line
Block BEQ ×N DCF ×N DMUX DPSK Receiver PM-AWG PM-AWG LD5 LD6 Pol. Scr. RZ-DPSK Transmitter (Odd) Pol. Scr.
25GHz or 33GHz spacing 8WDM
MUX
1075km x 11 times circulation =11833km
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(2) Transmission Line Configuration
DMF 73km span D+ D- D+ D- Block DCF Repeater output power +16.5dBm
DMF1075km Transmission Line
Average dispersion adjustment to avoid optical phase noise accumulation Combination of DMF+ and DMF- in a span
DMF+ : Large effective core area DMF- : Slope-matched DCF
- 1
- 0.8
- 0.6
- 0.4
- 0.2
0.2 0.4 0.6 0.8 1 1540 1545 1550 1555 1560 1565 Wavelength [nm] Dispersion [ps/nm/km]
NZ-DSF
DMF
Dispersion slope: < 0.01ps/nm2/km
▐ For very long distance transmission, we employed the Dispersion Managed Fiber (DMF) as transmission line. ▐ The DMF can achieve excellent dispersion flatness and greatly reduce nonlinearity effects.
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(3) Result
10Gb/s 25GHz-DWDM RZ-DPSK is feasible with almost the same performance as the case of 33GHz channel spacing.
8 9 10 11 12 13 14 15 16 17 4000 6000 8000 10000 12000 14000 16000 Transmission Distance [km] Q value [dB]
33GHz-Spacing 25GHz-Spacing
25GHz-spacing 33GHz-spacing
Channel Power : -4dBm/ch FEC Detection Limit : 8.8dB
> > 3 3dB Margin dB Margin
12,000km
▐ We measured the Q value performance dependency on the transmission distance with channel spacings
- f 25GHz and 33GHz
in order to confirm the impacts of narrowing channel spacing .
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6 8 10 12 14 16 18 1535 1540 1545 1550 1555 1560 1565 1570 Wavelength [nm] Q value [dB]
- 50
- 40
- 30
- 20
- 10
10 Power [dBm]
FEC Detection Limit : 8.8dB > 6dB Margin > 6dB Margin
Demonstration: 132x10Gb/s-6,500km transmission
All 132CHs have sufficient Q margins against FEC detection limit.
Q value Spectrum
▐ To demonstrate the extremely narrow channel spacing transmission using the fully-established 10Gb/s technologies, we conducted 132x10Gb/s-6,500km transmission experiment adopting RZ-DPSK modulated 132 signals with a 25GHz channel spacing.
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10Gb/s Line Terminal Equipments
Main features
- RZ-DPSK / RZ / NRZ modulation formats
- Enhanced FEC (Coding Gain 10dB)
- Various channel grid (25/33/50/100GHz)
with Tunable Light Source
- Various tributary interfaces
STM-64/OC-192, 10GbE LAN PHY STM-16/OC-48 x 4
- Tunable Dispersion Compensation Module
(TDCM)
- 32ch x 10G Transponders in one TPND Rack
- Maximum Capacity : 180ch DWDM
- OADM system support
- 2200mm(H) x 600mm(W) x 300mm(D)
TPND Rack WME Rack
▐ We have developed the Submarine Line Terminal Equipment supported 25GHz-spaced DWDM system.
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Conclusion
▐ We showed our recent development of 10Gb/s DWDM transmission technologies with extremely narrow channel spacing of 25GHz for submarine cable systems to achieve over Tb/s capacity. ▐ It has been verified that transmission over 12,000km with 25GHz-spaced RZ-DPSK signal is feasible with a performance comparable with that of 33GHz channel spacing.
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