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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 19, Iss. 15 — Jul. 18, 2011
  • pp: 14000–14007
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Full-duplex lightwave transport systems employing phase-modulated RoF and intensity-remodulated CATV signals

Chung-Yi Li, Heng-Sheng Su, Chia-Yi Chen, Hai-Han Lu, Hwan-Wen Chen, Ching-Hung Chang, and Chang-Han Jiang  »View Author Affiliations


Optics Express, Vol. 19, Issue 15, pp. 14000-14007 (2011)
http://dx.doi.org/10.1364/OE.19.014000


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Abstract

A full-duplex lightwave transport system employing phase-modulated radio-over-fiber (RoF) and intensity-remodulated CATV signals in two-way transmission is proposed and experimentally demonstrated. The transmission performances of RoF and CATV signals are investigated in bidirectional way, with the assistance of only one optical sideband and optical single sideband (SSB) schemes at the receiving sites. The experimental results show that the limitation on the optical modulation index (OMI) of the downlink RoF signal can be relaxed due to the constant intensity of phase modulation scheme. Impressive transmission performances of bit error rate (BER), carrier-to-noise ratio (CNR), composite second-order (CSO), and composite triple-beat (CTB) were obtained over two 20-km single-mode fiber (SMF) links. This proposed system reveals an outstanding one with economy and convenience to be installed.

© 2011 OSA

1. Introduction

2. Experimental setup

3. Experimental results and discussions

A phase-modulated optical carrier is generated by modulating the phase of a continuous wave (CW) light source, and its complex amplitude can be expressed as [13

13. Y. T. Hsueh, H. C. Chien, A. Chowdhury, J. Yu, and G. K. Chang, “Performance assessment of radio links using millimeter-wave over fiber technology with carrier suppression through modulation index enhancement,” J. Opt. Commun. Netw. 3(3), 254–258 (2011). [CrossRef]

]:
Eout(t)=E0n(j)nJn(β)ej(ω0+nωm)t
(1)
where E0 and ω0are the amplitude and angular frequency of the CW, β is the OMI, Jn(β) is the Bessel function of the first kind of order n, and ωm is the angular frequency of the driving signal. The phase-modulated optical carrier features multiple optical sidebands centered at ω0. It is clear that, from the Eq. (1), the amount of sideband is mainly affected by the β (OMI) value. The amount of sideband is proportionally increased with the increasing OMI value. A large OMI allows a PM to obtain many sidebands output; however; a small OMI allows a PM to obtain only the first-order sidebands output.

In parallel with verifying CATV performance, the measured BER curves of 1.25Gbps/10GHz data channel are presented in Fig. 3
Fig. 3 The measured BER curves of 1.25Gbps/10GHz data channel.
. For CATV on, the received optical power levels at the BER of 10−9 are −15.5 (with OBPF) and −13.2 (without OBPF) dBm, respectively. For CATV off, the received optical power levels at the BER of 10−9 are −18.3 (with OBPF) and −15.9 (without OBPF) dBm, respectively. Power penalties of 2.3 and 2.4 dB are obtained in systems due to the cancellation of RF power degradation induced by fiber dispersion. In DSB system, fiber dispersion leads to RF power degradation, in which causing fading problem and resulting in system performance degradation. In only one optical sideband system, since optical carrier and one of the sidebands are eliminated before detecting, the RF power degradation induced by fiber dispersion can be avoided. An error free transmission is achieved to demonstrate the feasibility of employing a PM to modulate the RF PB signal and an IM to remodulate the CATV one. In addition, the eye diagrams of different cases in Fig. 3 are shown in Fig. 4(a)
Fig. 4 (a) Eye diagram for case of 20km and CATV off (with OBPF).(b) Eye diagram for case of 20km and CATV off (without OBPF).(c) Eye diagram for case of 20km and CATV on (with OBPF).(d) Eye diagram for case of 20km and CATV on (without OBPF).
(20km and CATV off (with OBPF)), (b) (20km and CATV off (without OBPF)), (c) (20km and CATV on (with OBPF)), and (d) (20km and CATV on (without OBPF)), respectively. More undesired jitter and amplitude fluctuations are induced in Fig. 4(d) case; however, clear and open eye diagrams are obtained in Fig. 4(a), (b), and (c) cases.

Figure 5(a), (b) and (c)
Fig. 5 (a) The measured CNR values under NTSC channel number. (b) The measured CSO values under NTSC channel number. (c) The measured CTB values under NTSC channel number.
show the measured CNR, CSO and CTB values under NTSC channel number, respectively. For fiber optical CATV transport systems, the theoretical expression for CNR is [14

14. C. Bonang, and C. Y. Kuo, “Long distance 1550 nm fiber optic CATV supertrunking,” Harmonic Lightwaves Inc. Technical Report (1997).

]:
CNR=(CNRRIN1+(CNRth1+CNRshot1)+(CNRsigsp1+CNRspsp1))1
(2)
where CNRRIN results from the relative intensity noise (RIN) of LD; CNRth (due to thermal noise) and CNRshot (due to shot noise) are associated with the optical receiver; CNRsig-sp (due to signal-spontaneous beat noise) and CNRsp-sp (due to spontaneous-spontaneous beat noise) are associated with the EDFA. Owing to the insertion loss of OBPF (0.5 dB, in front of CATV receiver), the CNR value of systems with SSB format is degraded about 0.5 dB compared to the systems with DSB one. However, systems with SSB format still meet the CNR performance demand (≥50 dB). And further, it can be seen that the CNR value of systems with DSB format is deteriorated about 2 dB compared to the back-to-back (BTB) case. This CNR degradation can be attributed to the fiber loss, in which reducing the received optical power. The CNR value in AM-VSB channels would increase 1 dB as the optical power launched into the EDFA is increased 3 dBm.

For the CSO and CTB performances, there exist power penalties of ~6 dB between the BTB cases and optical DSB formats because of fiber dispersion-induced distortions. Nevertheless, CSO and CTB performances improvements of about 3 dB are achieved as SSB formats are used. These improvement results are due to the conversion of optical DSB format into optical SSB format to decrease the linewidth of the optical signal, in which leading to the reduction of the fiber dispersion. In an intensity modulation, the CSO and CTB distortions can be expressed as [15

15. H. H. Lu, “CSO/CTB Performances improvement by using optical VSB modulation technique,” IEEE Photon. Technol. Lett. 14(10), 1478–1480 (2002). [CrossRef]

]:
CSO=20log[NCSO[dG(P,λ)dλ]Δλ2G(P,λ)]
(3)
CTB=20log[NCTB[d2G(P,λ)dλ2]Δλ24G(P,λ)]
(4)
where NCSO and NCTB are the product counts, G(P,λ) is the gain of the EDFA, Δλ is the linewidth of the optical signal. It is effective to introduce optical SSB format to reduce the optical linewidth so that total fiber dispersion is reduced. There would be significant reductions in the CSO and CTB distortions since the CSO and CTB distortions are due to fiber dispersion.

4. Conclusions

References and links

1.

C. C. Lin, H. H. Lu, W. J. Ho, H. C. Peng, and C. Y. Li, “A bidirectional WDM transport system based on RSOAs and optoelectronic feedback technique,” IEEE Commun. Lett. 14(10), 969–971 (2010). [CrossRef]

2.

M. Omella1, I. Papagiannakis, B. Schrenk1, D. Klonidis, J. A. Lázaro, A. N. Birbas, J. Kikidis, and J. Prat, and I. Tomkos, “Full-duplex bidirectional transmission at 10 Gbps in WDM PONs with RSOA-based ONU using offset optical filtering and electronic equalization,” Opt. Express 17(7), 5008–5013 (2009). [CrossRef] [PubMed]

3.

C. W. Chow, “Wavelength remodulation using DPSK down-and-upstream with high extinction ratio for 10-Gb/s DWDM-passive optical networks,” IEEE Photon. Technol. Lett. 20(1), 12–14 (2008). [CrossRef]

4.

W. Y. Lin, C. H. Chang, P. C. Peng, H. H. Lu, and C. H. Huang, “Direct CATV modulation and phase remodulated radio-over-fiber transport system,” Opt. Express 18(10), 10301–10307 (2010). [CrossRef] [PubMed]

5.

C. W. Chow, C. H. Yeh, C. H. Wang, F. Y. Shih, and S. Chi, “Signal remodulation of OFDM-QAM for long reach carrier distributed passive optical networks,” IEEE Photon. Technol. Lett. 21(11), 715–717 (2009). [CrossRef]

6.

K. Y. Cho, Y. J. Lee, H. Y. Choi, A. Murakami, A. Agata, Y. Takushima, and Y. C. Chung, “Effects of reflection in RSOA-based WDM PON utilizing remodulation technique,” IEEE/OSA J,” Lightw. Technol. 27(10), 1286–1295 (2009). [CrossRef]

7.

M. Presi, R. Proietti, K. Prince, G. Contestabile, and E. Ciaramella, “A 80 km reach fully passive WDM-PON based on reflective ONUs,” Opt. Express 16(23), 19043–19048 (2008). [CrossRef] [PubMed]

8.

X. Yu, J. B. Jensen, D. Zibar, C. Peucheret, and I. T. Monroy, “Converged wireless and wireline access system based on optical phase modulation for both radio-over-fiber and baseband signals,” IEEE Photon. Technol. Lett. 20(21), 1816–1817 (2008). [CrossRef]

9.

J. Yu, Z. Jia, T. Wang, and G. Kung Chang, “A novel radio-over-fiber configuration using optical phase modulator to generate an optical mm-wave and centralized lightwave for uplink connection,” IEEE Photon. Technol. Lett. 19(3), 140–142 (2007). [CrossRef]

10.

W. J. Ho, H. C. Peng, H. H. Lu, C. L. Ying, and C. Y. Li, “Novel ROF/FTTX/CATV hybrid three-band transport system,” Opt. Express 19(7), 6980–6989 (2011). [CrossRef] [PubMed]

11.

C. H. Chang, H. S. Su, H. H. Lu, P. C. Peng, and H. W. Hu, “Integrating fiber to the home and POF in-door routing CATV transport system,” IEEE/OSA J. Lightw. Technol. 28(12), 1864–1869 (2010). [CrossRef]

12.

C. H. Yeh and C. W. Chow, “Heterogeneous radio-over-fiber passive access network architecture to mitigate Rayleigh backscattering interferometric beat noise,” Opt. Express 19(7), 5735–5740 (2011). [CrossRef] [PubMed]

13.

Y. T. Hsueh, H. C. Chien, A. Chowdhury, J. Yu, and G. K. Chang, “Performance assessment of radio links using millimeter-wave over fiber technology with carrier suppression through modulation index enhancement,” J. Opt. Commun. Netw. 3(3), 254–258 (2011). [CrossRef]

14.

C. Bonang, and C. Y. Kuo, “Long distance 1550 nm fiber optic CATV supertrunking,” Harmonic Lightwaves Inc. Technical Report (1997).

15.

H. H. Lu, “CSO/CTB Performances improvement by using optical VSB modulation technique,” IEEE Photon. Technol. Lett. 14(10), 1478–1480 (2002). [CrossRef]

OCIS Codes
(060.0060) Fiber optics and optical communications : Fiber optics and optical communications
(060.2360) Fiber optics and optical communications : Fiber optics links and subsystems
(350.4010) Other areas of optics : Microwaves

ToC Category:
Fiber Optics and Optical Communications

History
Original Manuscript: May 5, 2011
Revised Manuscript: June 30, 2011
Manuscript Accepted: July 1, 2011
Published: July 7, 2011

Citation
Chung-Yi Li, Heng-Sheng Su, Chia-Yi Chen, Hai-Han Lu, Hwan-Wen Chen, Ching-Hung Chang, and Chang-Han Jiang, "Full-duplex lightwave transport systems employing phase-modulated RoF and intensity-remodulated CATV signals," Opt. Express 19, 14000-14007 (2011)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-15-14000


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References

  1. C. C. Lin, H. H. Lu, W. J. Ho, H. C. Peng, and C. Y. Li, “A bidirectional WDM transport system based on RSOAs and optoelectronic feedback technique,” IEEE Commun. Lett. 14(10), 969–971 (2010). [CrossRef]
  2. M. Omella1, I. Papagiannakis, B. Schrenk1, D. Klonidis, J. A. Lázaro, A. N. Birbas, J. Kikidis, and J. Prat,andI. Tomkos, “Full-duplex bidirectional transmission at 10 Gbps in WDM PONs with RSOA-based ONU using offset optical filtering and electronic equalization,” Opt. Express 17(7), 5008–5013 (2009). [CrossRef] [PubMed]
  3. C. W. Chow, “Wavelength remodulation using DPSK down-and-upstream with high extinction ratio for 10-Gb/s DWDM-passive optical networks,” IEEE Photon. Technol. Lett. 20(1), 12–14 (2008). [CrossRef]
  4. W. Y. Lin, C. H. Chang, P. C. Peng, H. H. Lu, and C. H. Huang, “Direct CATV modulation and phase remodulated radio-over-fiber transport system,” Opt. Express 18(10), 10301–10307 (2010). [CrossRef] [PubMed]
  5. C. W. Chow, C. H. Yeh, C. H. Wang, F. Y. Shih, and S. Chi, “Signal remodulation of OFDM-QAM for long reach carrier distributed passive optical networks,” IEEE Photon. Technol. Lett. 21(11), 715–717 (2009). [CrossRef]
  6. K. Y. Cho, Y. J. Lee, H. Y. Choi, A. Murakami, A. Agata, Y. Takushima, and Y. C. Chung, “Effects of reflection in RSOA-based WDM PON utilizing remodulation technique,” IEEE/OSA J,” Lightw. Technol. 27(10), 1286–1295 (2009). [CrossRef]
  7. M. Presi, R. Proietti, K. Prince, G. Contestabile, and E. Ciaramella, “A 80 km reach fully passive WDM-PON based on reflective ONUs,” Opt. Express 16(23), 19043–19048 (2008). [CrossRef] [PubMed]
  8. X. Yu, J. B. Jensen, D. Zibar, C. Peucheret, and I. T. Monroy, “Converged wireless and wireline access system based on optical phase modulation for both radio-over-fiber and baseband signals,” IEEE Photon. Technol. Lett. 20(21), 1816–1817 (2008). [CrossRef]
  9. J. Yu, Z. Jia, T. Wang, and G. Kung Chang, “A novel radio-over-fiber configuration using optical phase modulator to generate an optical mm-wave and centralized lightwave for uplink connection,” IEEE Photon. Technol. Lett. 19(3), 140–142 (2007). [CrossRef]
  10. W. J. Ho, H. C. Peng, H. H. Lu, C. L. Ying, and C. Y. Li, “Novel ROF/FTTX/CATV hybrid three-band transport system,” Opt. Express 19(7), 6980–6989 (2011). [CrossRef] [PubMed]
  11. C. H. Chang, H. S. Su, H. H. Lu, P. C. Peng, and H. W. Hu, “Integrating fiber to the home and POF in-door routing CATV transport system,” IEEE/OSA J. Lightw. Technol. 28(12), 1864–1869 (2010). [CrossRef]
  12. C. H. Yeh and C. W. Chow, “Heterogeneous radio-over-fiber passive access network architecture to mitigate Rayleigh backscattering interferometric beat noise,” Opt. Express 19(7), 5735–5740 (2011). [CrossRef] [PubMed]
  13. Y. T. Hsueh, H. C. Chien, A. Chowdhury, J. Yu, and G. K. Chang, “Performance assessment of radio links using millimeter-wave over fiber technology with carrier suppression through modulation index enhancement,” J. Opt. Commun. Netw. 3(3), 254–258 (2011). [CrossRef]
  14. C. Bonang, and C. Y. Kuo, “Long distance 1550 nm fiber optic CATV supertrunking,” Harmonic Lightwaves Inc. Technical Report (1997).
  15. H. H. Lu, “CSO/CTB Performances improvement by using optical VSB modulation technique,” IEEE Photon. Technol. Lett. 14(10), 1478–1480 (2002). [CrossRef]

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