Abstract

We present and demonstrate a simple method of pulse-amplitude equalization in a rational harmonic mode-locked semiconductor ring laser, using a dual-drive Mach-Zehnder (MZ) modulator. Pulse-amplitude equalization was achieved by adjusting the voltages applied to both arms of the modulator, such that each mode-locked pulse experiences the same transmission coefficient in the transmission curve of the modulator. With this method, amplitude-equalized pulse trains with repetition rates of ~7.42GHz (third rational harmonic) and ~12.34GHz (fifth rational harmonic) were successfully obtained without any additional function to the ring laser itself.

© 2004 Optical Society of America

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References

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  1. C. Wu and N. K. Dutta, �??High-repetition-rate optical pulse generation using a rational harmonic mode-locking fiber laser,�?? IEEE J. Quantum Electron. 36, 145�??150 (2000).
    [CrossRef]
  2. N. Onodera, A. J. Lowery, L. Zhai, Z. Ahmed, and R. S. Tucker, �??Frequency multiplication in actively mode-locked semiconductor lasers,�?? Appl. Phys. Lett. 62, 1329�??1331 (1993).
    [CrossRef]
  3. Z. Ahmed and N. Onodera, �??High repetition rate optical pulse generation by frequency mudltiplication in actively modelocked fibre ring lasers,�?? Electron. Lett. 32, 455�??457 (1996).
    [CrossRef]
  4. M. -Y. Jeon, H. K. Lee, J. T. Ahn, K. H. Kim, D. S. Lim, and E. -H. Lee, �??Pulse-amplitude-equalized output from a rational harmonic mode-locked fiber laser,�?? Opt. Lett. 23, 855�??857 (1998).
    [CrossRef]
  5. H. J. Lee, K. Kim, H. G. Kim, �??Pulse-amplitude equalization of rational harmonic mode-locked fiber laser using a semiconductor optical amplifier loop mirror,�?? Opt. Commun. 160, 51�??56 (1999).
    [CrossRef]
  6. Z. Li, C. Lou, K. T. Chan, Y. Li, and Y. Gao, �??Theoretical and Experimental Study of Pulse-Amplitude-Equalization in a Rational Harmonic Mode-Locked Fiber Ring Laser,�?? IEEE J. Quantum Electron. 37, 33�??37 (2001).
    [CrossRef]
  7. C. G. Lee, Y. J. Kim, H. K. Choi, C. -S. Park, �??Pulse-amplitude equalization in a rational harmonic mode-locked semiconductor ring laser using optical feedback,�?? Opt. Commun. 209, 417�??425 (2002).
    [CrossRef]
  8. G. Zhu, H. Chen, and N. Dutta, �??Time domain analysis of a rational harmonic mode locked ring fiber laser,�?? J. Appl. Phys. 90, 2143�??2147 (1990).
    [CrossRef]
  9. A. Takada and H. Miyazawa, �??30GHz picosecond pulse generation from actively mode-locked erbium-doped fibre laser,�?? Electron. Lett. 26, 216�??217 (1990).
    [CrossRef]
  10. S.Walklin and J. Conradi, �??Effect of Mach-Zehnder Modulator DC Extinction Ratio on Residual Chirp-Induced Dispersion in 10-Gb/s Binary and AM-PSK Duobinary Lightwave Systems,�?? IEEE Photon. Technol. Lett. 9, 1400�??1402 (1997).
    [CrossRef]

Appl. Phys. Lett. (1)

N. Onodera, A. J. Lowery, L. Zhai, Z. Ahmed, and R. S. Tucker, �??Frequency multiplication in actively mode-locked semiconductor lasers,�?? Appl. Phys. Lett. 62, 1329�??1331 (1993).
[CrossRef]

Electron. Lett. (2)

Z. Ahmed and N. Onodera, �??High repetition rate optical pulse generation by frequency mudltiplication in actively modelocked fibre ring lasers,�?? Electron. Lett. 32, 455�??457 (1996).
[CrossRef]

A. Takada and H. Miyazawa, �??30GHz picosecond pulse generation from actively mode-locked erbium-doped fibre laser,�?? Electron. Lett. 26, 216�??217 (1990).
[CrossRef]

IEEE J. Quantum Electron. (2)

Z. Li, C. Lou, K. T. Chan, Y. Li, and Y. Gao, �??Theoretical and Experimental Study of Pulse-Amplitude-Equalization in a Rational Harmonic Mode-Locked Fiber Ring Laser,�?? IEEE J. Quantum Electron. 37, 33�??37 (2001).
[CrossRef]

C. Wu and N. K. Dutta, �??High-repetition-rate optical pulse generation using a rational harmonic mode-locking fiber laser,�?? IEEE J. Quantum Electron. 36, 145�??150 (2000).
[CrossRef]

IEEE Photon. Technol. Lett. (1)

S.Walklin and J. Conradi, �??Effect of Mach-Zehnder Modulator DC Extinction Ratio on Residual Chirp-Induced Dispersion in 10-Gb/s Binary and AM-PSK Duobinary Lightwave Systems,�?? IEEE Photon. Technol. Lett. 9, 1400�??1402 (1997).
[CrossRef]

J. Appl. Phys. (1)

G. Zhu, H. Chen, and N. Dutta, �??Time domain analysis of a rational harmonic mode locked ring fiber laser,�?? J. Appl. Phys. 90, 2143�??2147 (1990).
[CrossRef]

Opt. Commun. (2)

C. G. Lee, Y. J. Kim, H. K. Choi, C. -S. Park, �??Pulse-amplitude equalization in a rational harmonic mode-locked semiconductor ring laser using optical feedback,�?? Opt. Commun. 209, 417�??425 (2002).
[CrossRef]

H. J. Lee, K. Kim, H. G. Kim, �??Pulse-amplitude equalization of rational harmonic mode-locked fiber laser using a semiconductor optical amplifier loop mirror,�?? Opt. Commun. 160, 51�??56 (1999).
[CrossRef]

Opt. Lett. (1)

M. -Y. Jeon, H. K. Lee, J. T. Ahn, K. H. Kim, D. S. Lim, and E. -H. Lee, �??Pulse-amplitude-equalized output from a rational harmonic mode-locked fiber laser,�?? Opt. Lett. 23, 855�??857 (1998).
[CrossRef]

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Figures (9)

Fig. 1.
Fig. 1.

Timing diagrams for pulse-amplitude equalization. (a), (d) The input pulse train of the MZ modulator, (b), (e) transmission curve of the MZ modulator, and (c), (f) the output pulse train of the MZ modulator. [(a), (b), and (c)] are due to the small signal modulation (Vac <Vπ ) and [(d), (e), and (f)] large signal modulation (Vac >Vπ ).

Fig. 2.
Fig. 2.

Minimum modulation amplitude as a function of phase difference between the two applied signals for a pulse-amplitude equalization with mode-locking cases of p=3 and p=5.

Fig. 3.
Fig. 3.

Simulated pulse trains (solid line) and transmission curves (dotted line) for the third (p=3) rational harmonic mode-locking (a) without pulse-amplitude equalization (V bias1=1.51Vπ , V bias2=1.51Vπ and Vac =0.86Vπ ) and (b) with pulse-amplitude equalization (V bias1=1.30Vπ , V bias2=1.40Vπ and Vac =1.01Vπ ).

Fig. 4.
Fig. 4.

Simulated pulse trains (solid line) and transmission curves (dotted line) for the fifth (p=5) rational harmonic mode-locking (a) without pulse-amplitude equalization (V bias1=1.50Vπ , V bias2=1.50Vπ and Vac =0.83Vπ ) and (b) with pulse-amplitude equalization (V bias1=1.30Vπ , V bias2=1.72Vπ and Vac =1.12Vπ ).

Fig. 5.
Fig. 5.

Experimental setup. PC: polarization controller; PPG: pulse pattern generator; SOA: semiconductor optical amplifier; OTDL: optical tunable delay line; ATT: RF attenuator.

Fig. 6.
Fig. 6.

Measured optical pulse trains from the third (p=3) rational harmonic mode-locked semiconductor fiber ring laser (a) without and (b) with pulse-amplitude equalization.

Fig. 7.
Fig. 7.

RF spectra of the optical pulse trains from the third (p=3) rational harmonic modelocked semiconductor fiber ring laser. (a) Without and (b) with pulse-amplitude equalization.

Fig. 8.
Fig. 8.

Measured optical pulse trains from the fifth (p=5) rational harmonic mode-locked semiconductor fiber ring laser (a) without and (b) with pulse-amplitude equalization.

Fig. 9.
Fig. 9.

RF spectra of the optical pulse trains from the fifth (p=5) rational harmonic mode-locked semiconductor fiber ring laser. (a) Without and (b) with pulse-amplitude equalization.

Equations (7)

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E out ( t ) = E in ( t ) 2 [ exp ( j π v 1 ( t ) V π ) + γ exp ( j π v 2 ( t ) V π ) ] ,
v 1 ( t ) = V bias 1 + V ac sin ( 2 π f mod t + ϕ 1 )
v 2 ( t ) = V bias 2 + V ac sin ( 2 π f mod t + ϕ 2 ) ,
v 1 ( t ) = V bias 1 + V ac sin ( 2 π f mod t ) = V bias 1 + v ac ( t )
v 2 ( t ) = V bias 2 + V ac sin ( 2 π f mod t + π ) = V bias 2 + v ac ¯ ( t ) ,
I out ( t ) = E in ( t ) 2 4 [ 1 + γ 2 + 2 γ cos ( π v 1 ( t ) V π π v 2 ( t ) V π ) ] .
T MZM ( t ) = 1 4 [ 1 + γ 2 + 2 γ cos ( π v 1 ( t ) V π π v 2 ( t ) V π ) ] .

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