OSA's Digital Library

Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 18, Iss. 11 — May. 24, 2010
  • pp: 11827–11837
« Show journal navigation

Performances improvement in radio over fiber link through carrier suppression using Stimulated Brillouin scattering

Lan Liu, Shilie Zheng, Xianmin Zhang, Xiaofeng Jin, and Hao Chi  »View Author Affiliations


Optics Express, Vol. 18, Issue 11, pp. 11827-11837 (2010)
http://dx.doi.org/10.1364/OE.18.011827


View Full Text Article

Acrobat PDF (1666 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

The performances of radio-over-fiber (RoF) link with fixed incident optical power on photodetector (PD) are improved through carrier suppression method. Firstly, a precise analytical model is proposed to quantify the relationship between the improvement of link gain, noise figure (NF), spur-free dynamic range (SFDR) and the carrier suppression ratio x, in which, the modulation index m is fully considered for the first time to our knowledge. Then the optimum optical carrier-to-sideband ratio (CSR) for RoF link performances in both double-sideband and single-sideband modulation is obtained from the optimum x for the link performances. Finally the experiments with the carrier subtraction method realized by Stimulated Brillouin scattering (SBS) are carried out and the experimental results show good agreement with the simulation ones.

© 2010 OSA

1. Introduction

2. Theory

After suppressing the optical carrier, in order to keep PD incident optical power constant, E0(t) is amplified to E1(t) . The output of MZM after carrier subtraction is
Eafter(t)=2L2[J0(m)+2k=1+(1)kJ2k(m)cos(2kωrft)2k=0+(1)kJ2k+1(m)cos[(2k+1)ωrft]xJ0(m)]E1(t)=Lcos(πVDC2Vπ+mcosωrft)E1(t)2L2xJ0(m)E1(t)
(5)
Pafter(t)=Eafter(t)Eafter*(t)=P1L2{1+cosπVDCVπ[J0(2m)+2k=1+(1)kJ2k(2m)cos(2kωrft)]sinπVDCVπ[2k=0+(1)kJ2k+1(2m)cos[(2k+1)ωrft]]}P1L22xJ0(m)[J0(m)+2k=1+(1)kJ2k(m)cos(2kωrft)2k=0+(1)kJ2k+1(m)cos[(2k+1)ωrft]]+P1L2x2J0(m)2
(6)
Paverage_after=P1L2[1+J0(m)2(x22x)]
(7)
Here, P1 is the input optical power after the carrier subtraction, x is the carrier suppression ratio and Paverage_after is the average optical power incident on PD after the carrier suppression. Since PD incident optical power is constant, which means Paverage_after=Paverage_before , the relationship between P0 and P1 can be expressed as

P1P0=11+J0(m)2(x22x)
(8)

The RF power gain before and after carrier subtraction can be obtained from Eq. (3) and Eq. (6), respectively.
Gafter={P1L2[2J1(2m)4xJ0(m)J1(m)]}2Gbefore=[P0L22J1(2m)]2
(9)
Substituting Eq. (8) into Eq. (9), we can get the relationship between Gafter and Gbefore

GafterGbefore=[11+J0(m)2(x22x)J1(2m)2xJ0(m)J1(m)J1(2m)]2
(10)

A conclusion has been drawn in [13

13. R. D. Esman and K. J. Williams, “Wideband efficiency improvement of fiber optic systems by carrier subtraction,” IEEE Photon. Technol. Lett. 7(2), 218–220 (1995). [CrossRef]

] that an amount of carrier suppression results in an equal amount of RF power gain. From the above analysis, we can see that this result is only true when modulation index m is small enough that J1(2m)m , J0(m)1 and J1(m)m/2 . In this case, the RF power gain after carrier subtraction is increased by (1-x)−2 (supposing Gbefore as 1) and the optical carrier power after carrier subtraction is also reduced by (1-x)2. However, when the modulation index is not so small, the above approximation for the Bessel function is not exact, and the result is not precisely true.

Figure 1 also shows that the carrier subtraction method for the performance improvement is only useful when m is small. While m>0.5, it has little impact, which can be seen from curve e and f. In order to obtain a simple expression of the optimum x and CSR for this method when m is small, the above unexpanded expressions are simplified by ignoring the third-order and all the higher order sidebands, and leaving only the first item of Bessel function Taylor series. Thus, we can get the approximated expressions as below when m is small.

Ebefore(t)=2P0L2{J0(m)cos(ω0t)J1(m)[cos(ω0tωmodt)+cos(ω0t+ωmodt)]J2(m)[cos(ω0t2ωmodt)+cos(ω0t+2ωmodt)]}
(11)
Paverage_before=P0L2{[J0(m)]2+2[J1(m)]2+2[J2(m)]2}P0L2(1+m22)
(12)
Eafter(t)=2P1L2{(1x)J0(m)cos(ω0t+φ0)J1(m)[cos(ω0tωmodt)+cos(ω0t+ωmodt)]J2(m)[cos(ω0t2ωmodt)+cos(ω0t+2ωmodt)]}
(13)
Paverage_after=P1L2{[(1x)J0(m)]2+2[J1(m)]2+2[J2(m)]2}P1L2[(1x)2+m22]
(14)

Based on Eq. (14), the CSR, which is defined as the ratio of the optical power between the carrier and one of the first-order sidebands [12

12. C. Lim, M. Attygalle, A. Nirmalathas, D. Novak, and R. Waterhouse, “Analysis of optical carrier-to-sideband ratio for improving transmission performance in fiber-radio links,” IEEE Trans. Microw. Theory Tech. 54(5), 2181–2187 (2006). [CrossRef]

], can be obtained as

CSR=(1x)2m24
(15)

Gafter=[(1x)(1+m22)(1x)2+m22]2Gbefore
(16)

xG=1m22
(17)

In this case, substituting Eq. (17) into Eq. (15), the optimum CSR is equal to 3 dB for double-sideband modulation scheme. While for the single-sideband modulation with small m, the optimum carrier suppression ratio xG_singleband can be obtained under the same principle, which is shown as Eq. (18). It means the optimum CSR for single-sideband is 0 dB, coincident with [12

12. C. Lim, M. Attygalle, A. Nirmalathas, D. Novak, and R. Waterhouse, “Analysis of optical carrier-to-sideband ratio for improving transmission performance in fiber-radio links,” IEEE Trans. Microw. Theory Tech. 54(5), 2181–2187 (2006). [CrossRef]

].

xG_singleband=1m24
(18)

F=Noise_outGfkT0
(19)

The MZM biased at quadrature has no even-order harmonics in principle; however, carrier-suppression increases the even-order distortion. Using the same principle above, we can calculate the second-order harmonic relative to fundamental component with small m from Eq. (13), which is given as

G2f_afterGf_after=[xJ1(m)2(1x)J0(m)]2
(21)

With the carrier suppression ratio x increasing, the second-order harmonic component increases. Therefore this method is only limited in sub-octave bandwidth applications.

3. Experiments and results

The relationship between the second harmonic relative to fundamental component and the carrier suppression ratio x is shown in Fig. 7
Fig. 7 The results of the second-order harmonic relative to fundamental component with regards to carrier suppression ratio x. Solid line: theoretical curve of Eq. (21) with m = 0.3. Diamonds: experimental results.
, in which RF signal frequency is 9 GHz and m = 0.3. The solid line is the simulation results based on Eq. (21) and the diamond dots are the experimental ones. Good agreement is obtained. Obviously, the carrier subtraction method will increase the second-order harmonic, which should be limited in sub-octave applications.

4. Conclusion

Acknowledgements

This work was supported in part by National Natural Science Foundation of China (grant Nos. 60577028 and 60801003), the Program for New Century Excellent Talents in University (No. NCET-05-518), and the Specialized Research Fund for the Doctoral Program of Higher Education of China (grant No. 20060335074).

References and links

1.

E. Ackerman, S. Wanuga, D. Kasemset, A. S. Daryoush, and N. R. Samant, “Maximum dynamic range operation of a microwave external modulation fiber-optic link,” IEEE Trans. Microw. Theory Tech. 41(8), 1299–1306 (1993). [CrossRef]

2.

R. C. Williamson and R. D. Esman, “RF photonics,” J. Lightwave Technol. 26(9), 1145–1153 (2008). [CrossRef]

3.

C. H. Cox III, E. I. Ackerman, and J. L. Prince, “What do we need to get great link performance?” Microwave Photonics, International topical meeting (Germany, 1997), pp. 215–218.

4.

C. H. Cox III, E. I. Ackerman, G. E. Betts, and J. L. Prince, “Limits on the performance of RF-over-fiber links and their impact on device design,” IEEE Trans. Microw. Theory Tech. 54(2), 906–920 (2006). [CrossRef]

5.

A. Karim and J. Devenport, “Noise Figure Reduction in Externally Modulated Analog Fiber-Optic Links,” IEEE Photon. Technol. Lett. 19(5), 312–314 (2007). [CrossRef]

6.

M. L. Farewell, W. S. C. Chang, and D. R. Huber, “Increased linear dynamic range by low biasing the Mach-Zehnder modulator,” IEEE Photon. Technol. Lett. 5(7), 779–782 (1993). [CrossRef]

7.

J. Devenport and A. Karim, “Optimization of an externally modulated RF photonic link,” Fiber Integr. Opt. 27(1), 7–14 (2008).

8.

W. K. Burns, G. K. Gopalakrishnan, and R. P. Moeller, “Multi-octave operation of low-biased modulators by balanced detection,” IEEE Photon. Technol. Lett. 8(1), 130–132 (1996). [CrossRef]

9.

M. J. LaGasse, W. Charezenko, M. C. Hamilton, and S. Thaniyavarn, “Optical carrier filtering for high dynamic range fibre optic links,” Electron. Lett. 30(25), 2157–2158 (1994). [CrossRef]

10.

K. J. Williams and R. D. Esman, “Stimulated Brillouin scattering for improvement of microwave fiber-optic link efficiency,” Electron. Lett. 30(23), 1965–1966 (1994). [CrossRef]

11.

Y. C. Shen, X. M. Zhang, and K. S. Chen, “Stimulated Brillouin scattering for efficient improvement of radio-over-fiber systems,” Opt. Eng. 44(10), 105003 (2005). [CrossRef]

12.

C. Lim, M. Attygalle, A. Nirmalathas, D. Novak, and R. Waterhouse, “Analysis of optical carrier-to-sideband ratio for improving transmission performance in fiber-radio links,” IEEE Trans. Microw. Theory Tech. 54(5), 2181–2187 (2006). [CrossRef]

13.

R. D. Esman and K. J. Williams, “Wideband efficiency improvement of fiber optic systems by carrier subtraction,” IEEE Photon. Technol. Lett. 7(2), 218–220 (1995). [CrossRef]

14.

C. H. Cox III, G. E. Betts, and L. M. Johnson, “An analytic and experimental comparison of direct and external modulation in analog fiber-optic links,” IEEE Trans. Microw. Theory Tech. 38(5), 501–509 (1990). [CrossRef]

15.

C. Cox III, E. Ackerman, R. Helkey, and G. E. Betts, “Techniques and Performance of Intensity-Modulation Direct-Detection Analog Optical Links,” IEEE Trans. Microw. Theory Tech. 45(8), 1375–1383 (1997). [CrossRef]

OCIS Codes
(060.2360) Fiber optics and optical communications : Fiber optics links and subsystems
(060.4510) Fiber optics and optical communications : Optical communications
(060.4256) Fiber optics and optical communications : Networks, network optimization
(060.5625) Fiber optics and optical communications : Radio frequency photonics

ToC Category:
Fiber Optics and Optical Communications

History
Original Manuscript: November 30, 2009
Revised Manuscript: March 26, 2010
Manuscript Accepted: May 13, 2010
Published: May 20, 2010

Citation
Lan Liu, Shilie Zheng, Xianmin Zhang, Xiaofeng Jin, and Hao Chi, "Performances improvement in radio over fiber link through carrier suppression using Stimulated Brillouin scattering," Opt. Express 18, 11827-11837 (2010)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-18-11-11827


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. E. Ackerman, S. Wanuga, D. Kasemset, A. S. Daryoush, and N. R. Samant, “Maximum dynamic range operation of a microwave external modulation fiber-optic link,” IEEE Trans. Microw. Theory Tech. 41(8), 1299–1306 (1993). [CrossRef]
  2. R. C. Williamson and R. D. Esman, “RF photonics,” J. Lightwave Technol. 26(9), 1145–1153 (2008). [CrossRef]
  3. C. H. Cox III, E. I. Ackerman, and J. L. Prince, “What do we need to get great link performance?” Microwave Photonics, International topical meeting (Germany, 1997), pp. 215–218.
  4. C. H. Cox, E. I. Ackerman, G. E. Betts, and J. L. Prince, “Limits on the performance of RF-over-fiber links and their impact on device design,” IEEE Trans. Microw. Theory Tech. 54(2), 906–920 (2006). [CrossRef]
  5. A. Karim and J. Devenport, “Noise Figure Reduction in Externally Modulated Analog Fiber-Optic Links,” IEEE Photon. Technol. Lett. 19(5), 312–314 (2007). [CrossRef]
  6. M. L. Farewell, W. S. C. Chang, and D. R. Huber, “Increased linear dynamic range by low biasing the Mach-Zehnder modulator,” IEEE Photon. Technol. Lett. 5(7), 779–782 (1993). [CrossRef]
  7. J. Devenport and A. Karim, “Optimization of an externally modulated RF photonic link,” Fiber Integr. Opt. 27(1), 7–14 (2008).
  8. W. K. Burns, G. K. Gopalakrishnan, and R. P. Moeller, “Multi-octave operation of low-biased modulators by balanced detection,” IEEE Photon. Technol. Lett. 8(1), 130–132 (1996). [CrossRef]
  9. M. J. LaGasse, W. Charezenko, M. C. Hamilton, and S. Thaniyavarn, “Optical carrier filtering for high dynamic range fibre optic links,” Electron. Lett. 30(25), 2157–2158 (1994). [CrossRef]
  10. K. J. Williams and R. D. Esman, “Stimulated Brillouin scattering for improvement of microwave fiber-optic link efficiency,” Electron. Lett. 30(23), 1965–1966 (1994). [CrossRef]
  11. Y. C. Shen, X. M. Zhang, and K. S. Chen, “Stimulated Brillouin scattering for efficient improvement of radio-over-fiber systems,” Opt. Eng. 44(10), 105003 (2005). [CrossRef]
  12. C. Lim, M. Attygalle, A. Nirmalathas, D. Novak, and R. Waterhouse, “Analysis of optical carrier-to-sideband ratio for improving transmission performance in fiber-radio links,” IEEE Trans. Microw. Theory Tech. 54(5), 2181–2187 (2006). [CrossRef]
  13. R. D. Esman and K. J. Williams, “Wideband efficiency improvement of fiber optic systems by carrier subtraction,” IEEE Photon. Technol. Lett. 7(2), 218–220 (1995). [CrossRef]
  14. C. H. Cox, G. E. Betts, and L. M. Johnson, “An analytic and experimental comparison of direct and external modulation in analog fiber-optic links,” IEEE Trans. Microw. Theory Tech. 38(5), 501–509 (1990). [CrossRef]
  15. C. Cox, E. Ackerman, R. Helkey, and G. E. Betts, “Techniques and Performance of Intensity-Modulation Direct-Detection Analog Optical Links,” IEEE Trans. Microw. Theory Tech. 45(8), 1375–1383 (1997). [CrossRef]

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.


« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited