1. LiNbO3 Optical Single-Sideband Modulator
報 告 者：陳 嘉 怜
指導教授：王 維 新 博士

2. Outline Introduction Principle of Operation Experiment and Results
Summary
References

3. Introduction Single-Sideband (SSB) Modulator: Material :
z-cut lithium niobate (LN)
Fabrication:
titanium diffusion
Advantages:
Increase bandwidth efficiency
Reduce dispersion penalty
Suppress nonlinear effect

4. Principle of Operation
The integrated modulator consists of parallel Mach-Zehnder (MZ) intensity modulator with four optical modulation waveguides.

5. Signal Diagram Each frequency diagram shows Bessel function profiles
of J-4 to J4. J3
J-1 J0
frequency
J-3 J1

6. Optical Output Signals
In-phase modes are:
Out-of-phase modes are:
wc : optical carrier angular frequency
wm : modulation angular frequency
mf : modulation index

7. Experiment
Block diagrams of the SSB modulation measurement.

8. Measured Optical Spectra
Measured optical spectra of the SSB modulation. The dotted line shows the spectrum of a DFB-LD.

9. Optical Power vs Driving Voltage
Relationship between optical power of J-1 and J3modes and driving voltage.
-18.4dB

10. Modulated Optical Spectraf
f(t) J0 J1 J3
J-1
J-3
Modulate
DSB
SSB

11. Reduce Dispersion Penalty
Double sideband spectrum is susceptible to chromatic dispersion. Using SSB modulation will reduce dispersion penalty. f
f(t) J0 J1 J3
J-1
J-3

12. Suppress Nonlinear Effect
Without centered-cubic lattice(like LN), the
polarization vector is:
Reduce driving power to suppress the nonlinear effects in LN modulators.

13. Disadvantages
Using three Y-branches makes the on/off extinction ratio degraded.
A Y-branch
three Y-branches

14. Improved Structure input output A Y-branch
Using a Y-branch to improve the on/off extinction ratio.
input
output
A Y-branch

15. Summary
Optical SSB modulation with suppressions J0 and J3 of a 10GHz signal in a driving voltage of 6.3Vp-p
Advantages:
Increase bandwidth efficiency
Reduce dispersion penalty
Suppress nonlinear effect
Disadvantage:
Degrade on/off extinction ratio

16. References
S. Shimotsu, S. Oikawa, T. Saitou, N. Mitsugi, K. Kubodera, T. Kawanishi, and M. Isutsu, “Single Side-Band Modulation Performance of a LiNbO3 Integrated Modulator Consisting of Four-Phase Modulator Waveguides,”IEEE Photon. Technol. Lett., Vol. 13., No. 4, April 2001.
R. Hui, Senior Member, IEEE, B. Zhu, R. Huang, C. Allen, Senior Member, IEEE, K. Demarest, and D. Richards, “10Gb/s SCM Fiber System Using Optical SSB Modulation,” IEEE Photon. Technol. Lett. Vol. 13., No. 8, August 2001.
A. Loayssa, D. Benito, and M. J. Garde “Single-Sideband Suppressed-Carrier Modulation Using a Single-Electrode Electrooptic Modilator, ” IEEE Photon. Technol. Lett., Vol. 13., No. 8, August 2001.