## Theories and applications of chromatic dispersion penalty mitigation in all optical OFDM transmission system |

Optics Express, Vol. 21, Issue 2, pp. 1669-1674 (2013)

http://dx.doi.org/10.1364/OE.21.001669

Acrobat PDF (1618 KB)

### Abstract

Fiber chromatic dispersion (CD) in optical OFDM transmission degrades carrier orthogonality, resulting in a system penalty. Such penalty can be mitigated by per-carrier delay precompensation and spectrum filtering. We present a theoretical model to investigate the CD impairment in all-optical OFDM system, and demonstrate experimentally that both methods restore performance without overhead or guard interval.

© 2013 OSA

## 1. Introduction

## 2. Theoretical model for all optical OFDM

5. I. Kang, M. Rasras, X. Liu, S. Chandrasekhar, M. Cappuzzo, L. T. Gomez, Y. F. Chen, L. Buhl, S. Cabot, and J. Jaques, “All-optical OFDM transmission of 7 x 5-Gb/s data over 84-km standard single-mode fiber without dispersion compensation and time gating using a photonic-integrated optical DFT device,” Opt. Express **19**(10), 9111–9117 (2011). [CrossRef] [PubMed]

*m*= 0..

*N*-1) and DFT phase-shift

*n*-th demultiplexer output port. Here,

*N*and

*denote the number of OFDM carriers and the period of OFDM sampling, respectively, and hence the OFDM symbol period is*

^{τ}*T*

_{o}=

*Nτ*, and the carrier spacing is

*B*= 1/

*T*

_{o}. Neglecting a constant time delay factor of

*n*-th output port of the demultiplexer is then:

*i*in the time domain is represented as

*a*is the symbol value of on-off keying (OOK), phase shift keying (PSK), or quadrature amplitude modulation (QAM), and rectangle function

_{i}*c*, are the fiber CD coefficient, fiber length, wavelength, and speed of light, respectively. Finally, the optical output waveform of the

*i*-th carrier at the

*n*-th AO-OFDM demultiplexer port that has propagated through an amplified fiber transmission system with an uncompensated fiber length of

*L*can be found by numerical inverse Fourier transform of the following expression:

*N*= 4 carrier AO-OFDM system model as shown in Fig. 2. In this model, carriers 0, 1, and 2 are amplitude modulated as shown in Fig. 2(a). The carriers are separated by 10 GHz, and centered at a wavelength of 1550 nm. In a fiber transmission system with no CD, ICI is inherently canceled by DFT at designated temporal sampling positions of 50, 150, … 450 ps in Fig. 2(b). Notice that all the ICIs are confined within

*T*

_{o}= 100 ps. As CD is introduced by 20 km of an SMF-28 fiber, the ICIs spread broader than 100 ps, and shift in time (Fig. 2(c)) according to the group delay difference between different carriers. As a result, carrier-carrier orthogonality is degraded as depicted in Fig. 3(b) due to ICIs from adjacent and far carriers, which affect ICI-free time positions, compared with that of the transmitter AO-OFDM symbol as shown in Fig. 3(a). More careful speculations of the ICI position shift suggests a surprising observation; even though a spectral side lobe of a transmitted carrier experiences the same group delay as the interfering carrier at the same frequency, the ICI-free position shifts in time. Another observation is that ICI waveform broadening produces residual power at ICI-free positions resulting in interference even after orthogonal positions are aligned in the time domain.

5. I. Kang, M. Rasras, X. Liu, S. Chandrasekhar, M. Cappuzzo, L. T. Gomez, Y. F. Chen, L. Buhl, S. Cabot, and J. Jaques, “All-optical OFDM transmission of 7 x 5-Gb/s data over 84-km standard single-mode fiber without dispersion compensation and time gating using a photonic-integrated optical DFT device,” Opt. Express **19**(10), 9111–9117 (2011). [CrossRef] [PubMed]

8. D. Hillerkuss, R. Schmogrow, T. Schellinger, M. Jordan, M. Winter, G. Huber, T. Vallaitis, R. Bonk, P. Kleinow, F. Frey, M. Roeger, S. Koenig, A. Ludwig, A. Marculescu, J. Li, M. Hoh, M. Dreschmann, J. Meyer, S. Ben Ezra, N. Narkiss, B. Nebendahl, F. Parmigiani, P. Petropoulos, B. Resan, A. Oehler, K. Weingarten, T. Ellermeyer, J. Lutz, M. Moeller, M. Huebner, J. Becker, C. Koos, W. Freude, and J. Leuthold, “26 Tbit s^{−1} line-rate super-channel transmission utilizing all-optical fast Fourier transform processing,” Nat. Photonics **5**(6), 364–371 (2011). [CrossRef]

11. Z. Wang, K. S. Kravtsov, Y.-K. Huang, and P. R. Prucnal, “Optical FFT/IFFT circuit realization using arrayed waveguide gratings and the applications in all-optical OFDM system,” Opt. Express **19**(5), 4501–4512 (2011). [CrossRef] [PubMed]

## 3. Experimental results

4. G. Cincotti, “Characterization of a full encoder/decoder in the AWG configuration for code-based photonic routers-Part I: Modeling and design,” J. Lightwave Technol. **24**, 103–112 (2006). [CrossRef]

^{31}-1 to carriers alternatively to decorrelate adjacent carriers. We applied polarization interleaving on carriers to adjust adjacent carrier crosstalk to get reasonable ICIs for this proof of concept experiment. Hence, we can control the precompensation alignment of only 4 adjacent neighbors at a time since adjacent neighbors impose higher interference than far carriers. In each group, 3 carriers with the same power and polarization have a frequency separation of 5x10.7GHz. These 3 carriers are modulated, polarization controlled, and delay-adjusted for pre-compensation together. In our experimental setup, we characterized performance of carrier 8 for application of both delay precompensation and carrier narrow-band filtering. The filtering is applied on adjacent carriers 7 and 9. The 5-carrier groups are coupled together to form an OFDM symbol centered at a wavelength of 1549.8nm whose spectrum is shown in the inset of Fig. 5. The OFDM symbols are then transmitted through a 150-km dispersion managed fiber transmission system followed by additional fiber options of lengths of 0km, 54km, 75km, and 83km, consisting of single-mode fibers (SMF-28) with a CD coefficient of 16 ps/nm/km. At the receiver side, symbols are demultiplexed using another 1x16 AWG. We measure the BER of carriers from the AWG output with an O/E converter, clock data recovery, and bit-error detector.

*T*

_{0}. When group delay becomes larger than

*T*

_{0}, ISIpenalty becomes not negligible although ICI can be mitigated by precompensation.

## 4. Conclusion and discussions

## References and links

1. | H. Sanjoh, E. Yamada, and Y. Yoshikuni, “Optical orthogonal frequency division multiplexing using frequency/time domain filtering for high spectral efficiency up to 1 bit/s/Hz,” Optical Fiber Communication Conference (OFC) ThD1, (2002). |

2. | K. Lee, C. T. D. Thai, and J.-K. K. Rhee, “All optical discrete Fourier transform processor for 100 Gbps OFDM transmission,” Opt. Express |

3. | K. Takiguchi, T. Kitoh, A. Mori, M. Oguma, and H. Takahashi, “Optical orthogonal frequency division multiplexing demultiplexer using slab star coupler-based optical discrete Fourier transform circuit,” Opt. Lett. |

4. | G. Cincotti, “Characterization of a full encoder/decoder in the AWG configuration for code-based photonic routers-Part I: Modeling and design,” J. Lightwave Technol. |

5. | I. Kang, M. Rasras, X. Liu, S. Chandrasekhar, M. Cappuzzo, L. T. Gomez, Y. F. Chen, L. Buhl, S. Cabot, and J. Jaques, “All-optical OFDM transmission of 7 x 5-Gb/s data over 84-km standard single-mode fiber without dispersion compensation and time gating using a photonic-integrated optical DFT device,” Opt. Express |

6. | H. Chen, M. Chen, and S. Xie, “All-optical sampling orthogonal frequency-division multiplexing scheme for high-speed transmission system,” J. Lightwave Technol. |

7. | S. Yamamoto, K. Yonenaga, A. Sahara, F. Inuzuka, and A. Takada, “Achievement of subchannel frequency spacing less than symbol rate and improvement of dispersion tolerance in optical OFDM transmission,” J. Lightwave Technol. |

8. | D. Hillerkuss, R. Schmogrow, T. Schellinger, M. Jordan, M. Winter, G. Huber, T. Vallaitis, R. Bonk, P. Kleinow, F. Frey, M. Roeger, S. Koenig, A. Ludwig, A. Marculescu, J. Li, M. Hoh, M. Dreschmann, J. Meyer, S. Ben Ezra, N. Narkiss, B. Nebendahl, F. Parmigiani, P. Petropoulos, B. Resan, A. Oehler, K. Weingarten, T. Ellermeyer, J. Lutz, M. Moeller, M. Huebner, J. Becker, C. Koos, W. Freude, and J. Leuthold, “26 Tbit s |

9. | M. E. Marhic, “Discrete Fourier transforms by single-mode star networks,” Opt. Lett. |

10. | G. Cincotti, “Fiber wavelet filters,” J. Quantum Electron. |

11. | Z. Wang, K. S. Kravtsov, Y.-K. Huang, and P. R. Prucnal, “Optical FFT/IFFT circuit realization using arrayed waveguide gratings and the applications in all-optical OFDM system,” Opt. Express |

12. | S. Shimizu, G. Cincotti, and N. Wada, “Demonstration of 8x12.5 Gbit/s all-optical OFDM system with an arrayed waveguide grating and waveform reshaping,” in European Conference and Exhibition on Optical Communication (ECOC) (Optical Society of America, 2012), Th.1.A.2. |

13. | J.-K. K. Rhee, N. Cvijetic, N. Wada, and T. Wang, “Optical orthogonal frequency division multiplexed transmission using all-optical discrete Fourier transform,” Laser and Photon. Rev. (invited and submitted). |

**OCIS Codes**

(060.2330) Fiber optics and optical communications : Fiber optics communications

(060.4230) Fiber optics and optical communications : Multiplexing

(060.7140) Fiber optics and optical communications : Ultrafast processes in fibers

(070.2465) Fourier optics and signal processing : Finite analogs of Fourier transforms

**ToC Category:**

Subsystems for Optical Networks

**History**

Original Manuscript: October 3, 2012

Revised Manuscript: November 9, 2012

Manuscript Accepted: November 10, 2012

Published: January 16, 2013

**Virtual Issues**

European Conference on Optical Communication 2012 (2012) *Optics Express*

**Citation**

Malaz Kserawi, Satoshi Shimizu, Naoya Wada, Ahmed Galib Reza, and June-Koo Kevin Rhee, "Theories and applications of chromatic dispersion penalty mitigation in all optical OFDM transmission system," Opt. Express **21**, 1669-1674 (2013)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-2-1669

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### References

- H. Sanjoh, E. Yamada, and Y. Yoshikuni, “Optical orthogonal frequency division multiplexing using frequency/time domain filtering for high spectral efficiency up to 1 bit/s/Hz,” Optical Fiber Communication Conference (OFC) ThD1, (2002).
- K. Lee, C. T. D. Thai, and J.-K. K. Rhee, “All optical discrete Fourier transform processor for 100 Gbps OFDM transmission,” Opt. Express16(6), 4023–4028 (2008). [CrossRef] [PubMed]
- K. Takiguchi, T. Kitoh, A. Mori, M. Oguma, and H. Takahashi, “Optical orthogonal frequency division multiplexing demultiplexer using slab star coupler-based optical discrete Fourier transform circuit,” Opt. Lett.36(7), 1140–1142 (2011). [CrossRef] [PubMed]
- G. Cincotti, “Characterization of a full encoder/decoder in the AWG configuration for code-based photonic routers-Part I: Modeling and design,” J. Lightwave Technol.24, 103–112 (2006). [CrossRef]
- I. Kang, M. Rasras, X. Liu, S. Chandrasekhar, M. Cappuzzo, L. T. Gomez, Y. F. Chen, L. Buhl, S. Cabot, and J. Jaques, “All-optical OFDM transmission of 7 x 5-Gb/s data over 84-km standard single-mode fiber without dispersion compensation and time gating using a photonic-integrated optical DFT device,” Opt. Express19(10), 9111–9117 (2011). [CrossRef] [PubMed]
- H. Chen, M. Chen, and S. Xie, “All-optical sampling orthogonal frequency-division multiplexing scheme for high-speed transmission system,” J. Lightwave Technol.27(21), 4848–4854 (2009). [CrossRef]
- S. Yamamoto, K. Yonenaga, A. Sahara, F. Inuzuka, and A. Takada, “Achievement of subchannel frequency spacing less than symbol rate and improvement of dispersion tolerance in optical OFDM transmission,” J. Lightwave Technol.28(1), 157–163 (2010). [CrossRef]
- D. Hillerkuss, R. Schmogrow, T. Schellinger, M. Jordan, M. Winter, G. Huber, T. Vallaitis, R. Bonk, P. Kleinow, F. Frey, M. Roeger, S. Koenig, A. Ludwig, A. Marculescu, J. Li, M. Hoh, M. Dreschmann, J. Meyer, S. Ben Ezra, N. Narkiss, B. Nebendahl, F. Parmigiani, P. Petropoulos, B. Resan, A. Oehler, K. Weingarten, T. Ellermeyer, J. Lutz, M. Moeller, M. Huebner, J. Becker, C. Koos, W. Freude, and J. Leuthold, “26 Tbit s−1 line-rate super-channel transmission utilizing all-optical fast Fourier transform processing,” Nat. Photonics5(6), 364–371 (2011). [CrossRef]
- M. E. Marhic, “Discrete Fourier transforms by single-mode star networks,” Opt. Lett.12(1), 63–65 (1987). [CrossRef] [PubMed]
- G. Cincotti, “Fiber wavelet filters,” J. Quantum Electron.38(10), 1420–1427 (2002). [CrossRef]
- Z. Wang, K. S. Kravtsov, Y.-K. Huang, and P. R. Prucnal, “Optical FFT/IFFT circuit realization using arrayed waveguide gratings and the applications in all-optical OFDM system,” Opt. Express19(5), 4501–4512 (2011). [CrossRef] [PubMed]
- S. Shimizu, G. Cincotti, and N. Wada, “Demonstration of 8x12.5 Gbit/s all-optical OFDM system with an arrayed waveguide grating and waveform reshaping,” in European Conference and Exhibition on Optical Communication (ECOC) (Optical Society of America, 2012), Th.1.A.2.
- J.-K. K. Rhee, N. Cvijetic, N. Wada, and T. Wang, “Optical orthogonal frequency division multiplexed transmission using all-optical discrete Fourier transform,” Laser and Photon. Rev. (invited and submitted).

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