Abstract

We demonstrate the use of coherent population oscillations (CPO) to realize a monolithically integrated semiconductor device which allows voltage controlled tuning of the group velocity corresponding to a phase shift of up to 55 degrees at a frequency of 10 GHz. By combining sections of slow and fast light, corresponding to absorption and gain, we demonstrate control of both the slow-down factor and the signal amplitude, which is important for applications as true-time delay in microwave photonics. The physics of CPO is discussed in relation to electromagnetically induced transparency (EIT). In particular, we demonstrate and explain the possibility of achieving transparency when using the effect of CPO despite the fact that it relies on only a partial saturation of an absorption line.

© 2006 Optical Society of America

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References

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  1. L. V. Hau, S. E. Harris, Z. Dutton, and C. H. Behroozi, "Light speed reduction to 17 meters per second in an ultracold atomic gas," Nature 397, 594-598 (1999).
    [CrossRef]
  2. M. S. Bigelow, N. N. Lepeshkin, and R. W. Boyd, "Observation of ultraslow light propagation in a ruby crystal at room temperature," Phys. Rev. Lett. 90, 113903-1-4 (2003).
    [CrossRef]
  3. M. S. Bigelow, N. N. Lepeshkin, and R. W. Boyd, "Superluminal and slow light propagation in a room-temperature solid," Science 301, 200-202 (2003).
    [CrossRef] [PubMed]
  4. P. Ku, F. Sedgwick, C. J. Chang-Hasnain, P. Palinginis, T. Li, H. Wang, S. Chang, and S. Chuang, "Slow light in semiconductor quantum wells," Opt. Lett. 29, 2291 (2004).
    [CrossRef] [PubMed]
  5. P. Palinginis, S. Crankshaw and F. Sedgwick, "Ultra-slow light (<200 m/s) propagation in a semiconductor nanostructure," Appl. Phys. Lett. 87, 171102 (2005).
    [CrossRef]
  6. Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
    [CrossRef] [PubMed]
  7. K. Y. Song, M. G. Herráez, and L. Thévenaz, "Observation of pulse delaying and advancement in optical fibers using stimulated Brillouin scattering," Opt. Express 13, 82-88 (2005).
    [CrossRef] [PubMed]
  8. D. Dahan and G. Eisenstein, "Tunable all optical delay via slow and fast light propagation in a Raman assisted fiber optical parametric amplifier: a route to all optical buffering," Opt. Express 13, 6234 (2005).
    [CrossRef] [PubMed]
  9. J. Mørk, R. Kjær, M. van der Poel, and K. Yvind, "Slow light in a semiconductor waveguide at gigahertz frequencies," Opt. Express 13, 8136-8145 (2005).
    [CrossRef] [PubMed]
  10. Y. A. Vlasov, M. O’Boyle, H. F. Hamann, and S. J. McNab, "Active control of slow light on a chip with photonic crystal waveguides," Nature 438, 65 (2005).
    [CrossRef] [PubMed]
  11. M. Fleischhauer, A. Imamoglu, and J. P. Marangos, "Electromagnetically induced transparency: Optics in coherent media," Rev. Modern Physics 77, 633 (2005).
    [CrossRef]
  12. J. C. Chang-Hasnain, P.-C. Ku, J. Kim, and S.-L. Chuang, "Variable optical buffer using slow-light in semiconductor nanostructures," Proc. IEEE 91, 1884 (2003).
    [CrossRef]
  13. A. Uskov, J. Mørk, and J. Mark, "Wave mixing in semiconductor laser amplifiers due to carrier heating and spectral-hole burning," IEEE J. Quantum Electron. 30, 1769 (1994).
    [CrossRef]
  14. M. O. Scully and M. S. Zuabairy, Quantum Optics, (Cambridge University Press, Cambride UK, 1997).
  15. R. S. Tucker, P.-C. Ku, and C. J. Chang-Hasnain, "Slow-light optical buffers: capabilities and fundamental limitations," J. Lightwave Technol. 23, 4046 (2005).
    [CrossRef]
  16. P. Jänes, J. Tidström, and L. Thylén, "Limits on optical pulse compression and delay bandwidth product in electromagnetically induced transparency media," J. Lightwave Technol. 23, 3893 (2005).
    [CrossRef]
  17. F. Öhman, K. Yvind and J. Mørk, "Slow light at high frequencies in an amplifying semiconductor waveguide," in Proceedings of Conference on Lasers and Electro-Optics, CMN1, Long Beach USA (2006).
  18. A. V. Uskov, F. G. Sedgwick, and C. J. Chang-Hasnain, "Delay limit of slow light in semiconductor optical amplifiers," IEEE Photon. Technol. Lett. 18, 731-733 (2006).
    [CrossRef]
  19. M. van der. Poel, J. Mørk, and J. M. Hvam, "Controllable delay of ultrashort optical pulses in a semiconductor quantum dot amplifier," Opt. Express 13, 8032-8037 (2005).
    [CrossRef]
  20. H. Su, P. Kondratko, and S. L. Chuang, "Variable optical delay using population oscillation and four-wave-mixing in semiconductor optical amplifiers," Opt. Express 13, 4800-4807 (2006).
    [CrossRef]
  21. Y. Chen, F. Öhman and J. Mørk, "Large Signal Modulation and Distortion in a Microwave Phase Shifter Based on Slow Light in a Semiconductor Waveguide." in Proceedings of Conference on Lasers and Electro-Optics, CMN2, Long Beach USA (2006).

2006

A. V. Uskov, F. G. Sedgwick, and C. J. Chang-Hasnain, "Delay limit of slow light in semiconductor optical amplifiers," IEEE Photon. Technol. Lett. 18, 731-733 (2006).
[CrossRef]

H. Su, P. Kondratko, and S. L. Chuang, "Variable optical delay using population oscillation and four-wave-mixing in semiconductor optical amplifiers," Opt. Express 13, 4800-4807 (2006).
[CrossRef]

2005

P. Palinginis, S. Crankshaw and F. Sedgwick, "Ultra-slow light (<200 m/s) propagation in a semiconductor nanostructure," Appl. Phys. Lett. 87, 171102 (2005).
[CrossRef]

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

Y. A. Vlasov, M. O’Boyle, H. F. Hamann, and S. J. McNab, "Active control of slow light on a chip with photonic crystal waveguides," Nature 438, 65 (2005).
[CrossRef] [PubMed]

M. Fleischhauer, A. Imamoglu, and J. P. Marangos, "Electromagnetically induced transparency: Optics in coherent media," Rev. Modern Physics 77, 633 (2005).
[CrossRef]

K. Y. Song, M. G. Herráez, and L. Thévenaz, "Observation of pulse delaying and advancement in optical fibers using stimulated Brillouin scattering," Opt. Express 13, 82-88 (2005).
[CrossRef] [PubMed]

D. Dahan and G. Eisenstein, "Tunable all optical delay via slow and fast light propagation in a Raman assisted fiber optical parametric amplifier: a route to all optical buffering," Opt. Express 13, 6234 (2005).
[CrossRef] [PubMed]

M. van der. Poel, J. Mørk, and J. M. Hvam, "Controllable delay of ultrashort optical pulses in a semiconductor quantum dot amplifier," Opt. Express 13, 8032-8037 (2005).
[CrossRef]

J. Mørk, R. Kjær, M. van der Poel, and K. Yvind, "Slow light in a semiconductor waveguide at gigahertz frequencies," Opt. Express 13, 8136-8145 (2005).
[CrossRef] [PubMed]

P. Jänes, J. Tidström, and L. Thylén, "Limits on optical pulse compression and delay bandwidth product in electromagnetically induced transparency media," J. Lightwave Technol. 23, 3893 (2005).
[CrossRef]

R. S. Tucker, P.-C. Ku, and C. J. Chang-Hasnain, "Slow-light optical buffers: capabilities and fundamental limitations," J. Lightwave Technol. 23, 4046 (2005).
[CrossRef]

2004

2003

M. S. Bigelow, N. N. Lepeshkin, and R. W. Boyd, "Superluminal and slow light propagation in a room-temperature solid," Science 301, 200-202 (2003).
[CrossRef] [PubMed]

J. C. Chang-Hasnain, P.-C. Ku, J. Kim, and S.-L. Chuang, "Variable optical buffer using slow-light in semiconductor nanostructures," Proc. IEEE 91, 1884 (2003).
[CrossRef]

1999

L. V. Hau, S. E. Harris, Z. Dutton, and C. H. Behroozi, "Light speed reduction to 17 meters per second in an ultracold atomic gas," Nature 397, 594-598 (1999).
[CrossRef]

1994

A. Uskov, J. Mørk, and J. Mark, "Wave mixing in semiconductor laser amplifiers due to carrier heating and spectral-hole burning," IEEE J. Quantum Electron. 30, 1769 (1994).
[CrossRef]

Behroozi, C. H.

L. V. Hau, S. E. Harris, Z. Dutton, and C. H. Behroozi, "Light speed reduction to 17 meters per second in an ultracold atomic gas," Nature 397, 594-598 (1999).
[CrossRef]

Bigelow, M. S.

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

M. S. Bigelow, N. N. Lepeshkin, and R. W. Boyd, "Superluminal and slow light propagation in a room-temperature solid," Science 301, 200-202 (2003).
[CrossRef] [PubMed]

Boyd, R. W.

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

M. S. Bigelow, N. N. Lepeshkin, and R. W. Boyd, "Superluminal and slow light propagation in a room-temperature solid," Science 301, 200-202 (2003).
[CrossRef] [PubMed]

Chang, S.

Chang-Hasnain, C. J.

Chang-Hasnain, J. C.

J. C. Chang-Hasnain, P.-C. Ku, J. Kim, and S.-L. Chuang, "Variable optical buffer using slow-light in semiconductor nanostructures," Proc. IEEE 91, 1884 (2003).
[CrossRef]

Chuang, S.

Chuang, S. L.

H. Su, P. Kondratko, and S. L. Chuang, "Variable optical delay using population oscillation and four-wave-mixing in semiconductor optical amplifiers," Opt. Express 13, 4800-4807 (2006).
[CrossRef]

Chuang, S.-L.

J. C. Chang-Hasnain, P.-C. Ku, J. Kim, and S.-L. Chuang, "Variable optical buffer using slow-light in semiconductor nanostructures," Proc. IEEE 91, 1884 (2003).
[CrossRef]

Crankshaw, S.

P. Palinginis, S. Crankshaw and F. Sedgwick, "Ultra-slow light (<200 m/s) propagation in a semiconductor nanostructure," Appl. Phys. Lett. 87, 171102 (2005).
[CrossRef]

Dahan, D.

Dutton, Z.

L. V. Hau, S. E. Harris, Z. Dutton, and C. H. Behroozi, "Light speed reduction to 17 meters per second in an ultracold atomic gas," Nature 397, 594-598 (1999).
[CrossRef]

Eisenstein, G.

Fleischhauer, M.

M. Fleischhauer, A. Imamoglu, and J. P. Marangos, "Electromagnetically induced transparency: Optics in coherent media," Rev. Modern Physics 77, 633 (2005).
[CrossRef]

Gaeta, A. L.

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

Gauthier, D. J.

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

Hamann, H. F.

Y. A. Vlasov, M. O’Boyle, H. F. Hamann, and S. J. McNab, "Active control of slow light on a chip with photonic crystal waveguides," Nature 438, 65 (2005).
[CrossRef] [PubMed]

Harris, S. E.

L. V. Hau, S. E. Harris, Z. Dutton, and C. H. Behroozi, "Light speed reduction to 17 meters per second in an ultracold atomic gas," Nature 397, 594-598 (1999).
[CrossRef]

Hau, L. V.

L. V. Hau, S. E. Harris, Z. Dutton, and C. H. Behroozi, "Light speed reduction to 17 meters per second in an ultracold atomic gas," Nature 397, 594-598 (1999).
[CrossRef]

Herráez, M. G.

Imamoglu, A.

M. Fleischhauer, A. Imamoglu, and J. P. Marangos, "Electromagnetically induced transparency: Optics in coherent media," Rev. Modern Physics 77, 633 (2005).
[CrossRef]

Jänes, P.

Kim, J.

J. C. Chang-Hasnain, P.-C. Ku, J. Kim, and S.-L. Chuang, "Variable optical buffer using slow-light in semiconductor nanostructures," Proc. IEEE 91, 1884 (2003).
[CrossRef]

Kjær, R.

Kondratko, P.

H. Su, P. Kondratko, and S. L. Chuang, "Variable optical delay using population oscillation and four-wave-mixing in semiconductor optical amplifiers," Opt. Express 13, 4800-4807 (2006).
[CrossRef]

Ku, P.

Ku, P.-C.

R. S. Tucker, P.-C. Ku, and C. J. Chang-Hasnain, "Slow-light optical buffers: capabilities and fundamental limitations," J. Lightwave Technol. 23, 4046 (2005).
[CrossRef]

J. C. Chang-Hasnain, P.-C. Ku, J. Kim, and S.-L. Chuang, "Variable optical buffer using slow-light in semiconductor nanostructures," Proc. IEEE 91, 1884 (2003).
[CrossRef]

Lepeshkin, N. N.

M. S. Bigelow, N. N. Lepeshkin, and R. W. Boyd, "Superluminal and slow light propagation in a room-temperature solid," Science 301, 200-202 (2003).
[CrossRef] [PubMed]

Li, T.

Marangos, J. P.

M. Fleischhauer, A. Imamoglu, and J. P. Marangos, "Electromagnetically induced transparency: Optics in coherent media," Rev. Modern Physics 77, 633 (2005).
[CrossRef]

Mark, J.

A. Uskov, J. Mørk, and J. Mark, "Wave mixing in semiconductor laser amplifiers due to carrier heating and spectral-hole burning," IEEE J. Quantum Electron. 30, 1769 (1994).
[CrossRef]

McNab, S. J.

Y. A. Vlasov, M. O’Boyle, H. F. Hamann, and S. J. McNab, "Active control of slow light on a chip with photonic crystal waveguides," Nature 438, 65 (2005).
[CrossRef] [PubMed]

Mørk, J.

J. Mørk, R. Kjær, M. van der Poel, and K. Yvind, "Slow light in a semiconductor waveguide at gigahertz frequencies," Opt. Express 13, 8136-8145 (2005).
[CrossRef] [PubMed]

A. Uskov, J. Mørk, and J. Mark, "Wave mixing in semiconductor laser amplifiers due to carrier heating and spectral-hole burning," IEEE J. Quantum Electron. 30, 1769 (1994).
[CrossRef]

O’Boyle, M.

Y. A. Vlasov, M. O’Boyle, H. F. Hamann, and S. J. McNab, "Active control of slow light on a chip with photonic crystal waveguides," Nature 438, 65 (2005).
[CrossRef] [PubMed]

Okawachi, Y.

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

Palinginis, P.

P. Palinginis, S. Crankshaw and F. Sedgwick, "Ultra-slow light (<200 m/s) propagation in a semiconductor nanostructure," Appl. Phys. Lett. 87, 171102 (2005).
[CrossRef]

P. Ku, F. Sedgwick, C. J. Chang-Hasnain, P. Palinginis, T. Li, H. Wang, S. Chang, and S. Chuang, "Slow light in semiconductor quantum wells," Opt. Lett. 29, 2291 (2004).
[CrossRef] [PubMed]

Schweinsberg, A.

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

Sedgwick, F.

P. Palinginis, S. Crankshaw and F. Sedgwick, "Ultra-slow light (<200 m/s) propagation in a semiconductor nanostructure," Appl. Phys. Lett. 87, 171102 (2005).
[CrossRef]

P. Ku, F. Sedgwick, C. J. Chang-Hasnain, P. Palinginis, T. Li, H. Wang, S. Chang, and S. Chuang, "Slow light in semiconductor quantum wells," Opt. Lett. 29, 2291 (2004).
[CrossRef] [PubMed]

Sedgwick, F. G.

A. V. Uskov, F. G. Sedgwick, and C. J. Chang-Hasnain, "Delay limit of slow light in semiconductor optical amplifiers," IEEE Photon. Technol. Lett. 18, 731-733 (2006).
[CrossRef]

Sharping, J. E.

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

Song, K. Y.

Su, H.

H. Su, P. Kondratko, and S. L. Chuang, "Variable optical delay using population oscillation and four-wave-mixing in semiconductor optical amplifiers," Opt. Express 13, 4800-4807 (2006).
[CrossRef]

Thévenaz, L.

Thylén, L.

Tidström, J.

Tucker, R. S.

Uskov, A.

A. Uskov, J. Mørk, and J. Mark, "Wave mixing in semiconductor laser amplifiers due to carrier heating and spectral-hole burning," IEEE J. Quantum Electron. 30, 1769 (1994).
[CrossRef]

Uskov, A. V.

A. V. Uskov, F. G. Sedgwick, and C. J. Chang-Hasnain, "Delay limit of slow light in semiconductor optical amplifiers," IEEE Photon. Technol. Lett. 18, 731-733 (2006).
[CrossRef]

van der Poel, M.

Vlasov, Y. A.

Y. A. Vlasov, M. O’Boyle, H. F. Hamann, and S. J. McNab, "Active control of slow light on a chip with photonic crystal waveguides," Nature 438, 65 (2005).
[CrossRef] [PubMed]

Wang, H.

Yvind, K.

Zhu, Z.

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

Appl. Phys. Lett.

P. Palinginis, S. Crankshaw and F. Sedgwick, "Ultra-slow light (<200 m/s) propagation in a semiconductor nanostructure," Appl. Phys. Lett. 87, 171102 (2005).
[CrossRef]

IEEE J. Quantum Electron.

A. Uskov, J. Mørk, and J. Mark, "Wave mixing in semiconductor laser amplifiers due to carrier heating and spectral-hole burning," IEEE J. Quantum Electron. 30, 1769 (1994).
[CrossRef]

J. Lightwave Technol.

Nature

Y. A. Vlasov, M. O’Boyle, H. F. Hamann, and S. J. McNab, "Active control of slow light on a chip with photonic crystal waveguides," Nature 438, 65 (2005).
[CrossRef] [PubMed]

L. V. Hau, S. E. Harris, Z. Dutton, and C. H. Behroozi, "Light speed reduction to 17 meters per second in an ultracold atomic gas," Nature 397, 594-598 (1999).
[CrossRef]

Opt. Express

Opt. Lett.

Photon. Technol. Lett.

A. V. Uskov, F. G. Sedgwick, and C. J. Chang-Hasnain, "Delay limit of slow light in semiconductor optical amplifiers," IEEE Photon. Technol. Lett. 18, 731-733 (2006).
[CrossRef]

Phys. Rev. Lett.

Y. Okawachi, M. S. Bigelow, J. E. Sharping, Z. Zhu, A. Schweinsberg, D. J. Gauthier, R. W. Boyd and A. L. Gaeta, "Tunable all-optical delays via Brillouin slow light in an optical fiber," Phys. Rev. Lett. 94, 153902 (2005).
[CrossRef] [PubMed]

Proc. IEEE

J. C. Chang-Hasnain, P.-C. Ku, J. Kim, and S.-L. Chuang, "Variable optical buffer using slow-light in semiconductor nanostructures," Proc. IEEE 91, 1884 (2003).
[CrossRef]

Rev. Modern Physics

M. Fleischhauer, A. Imamoglu, and J. P. Marangos, "Electromagnetically induced transparency: Optics in coherent media," Rev. Modern Physics 77, 633 (2005).
[CrossRef]

Science

M. S. Bigelow, N. N. Lepeshkin, and R. W. Boyd, "Superluminal and slow light propagation in a room-temperature solid," Science 301, 200-202 (2003).
[CrossRef] [PubMed]

Other

M. S. Bigelow, N. N. Lepeshkin, and R. W. Boyd, "Observation of ultraslow light propagation in a ruby crystal at room temperature," Phys. Rev. Lett. 90, 113903-1-4 (2003).
[CrossRef]

M. O. Scully and M. S. Zuabairy, Quantum Optics, (Cambridge University Press, Cambride UK, 1997).

F. Öhman, K. Yvind and J. Mørk, "Slow light at high frequencies in an amplifying semiconductor waveguide," in Proceedings of Conference on Lasers and Electro-Optics, CMN1, Long Beach USA (2006).

Y. Chen, F. Öhman and J. Mørk, "Large Signal Modulation and Distortion in a Microwave Phase Shifter Based on Slow Light in a Semiconductor Waveguide." in Proceedings of Conference on Lasers and Electro-Optics, CMN2, Long Beach USA (2006).

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Figures (5)

Fig. 1.
Fig. 1.

Level diagrams and typical examples of susceptibilities for electromagnetically induced transparency (EIT, left column) and coherent population oscillations (CPO, right column) versus detuning frequency. The level schemes (upper row) illustrate the choice of control and probe photon energies, ħωco and ħωpr , for the two schemes of excitation. Below, the imaginary and real parts of the susceptibilities are depicted, with dashed lines showing the susceptibilities for zero control signal. The probe frequency is normalized with respect to the 2-1 dephasing time for EIT and with respect to the carrier lifetime for CPO

Fig. 2.
Fig. 2.

The device under investigation. Schematic (top) and photo (bottom) of the examined device consisting of concatenated semiconductor optical amplifiers (SOA) and electro absorbers (EA).

Fig. 3.
Fig. 3.

Transmitted intensity modulation showing time delay. The measured optical signal intensity is shown as a function of time for constant optical input power and three different values of EA reverse bias. The signals are normalised to their respective mean value. Two SOA-EA pairs are concatenated. The first and second SOAs are biased at 80 and 30 mA, respectively and both EA sections are biased at the reverse voltage indicated in the figure legend. The modulation frequency is 10 GHz, the optical input power is 6.8 dBm and the wavelength of the optical carrier is 1555 nm.

Fig. 4.
Fig. 4.

Measured phase and amplitude shift. Contour plots of phase shift (colour contours) and amplitude change (black contours) are shown as function of EA reverse bias and optical input power. The first and second SOAs are biased at 80 and 30 mA, respectively and both EA sections are biased at the reverse voltage indicated in the figure. The modulation frequency is 10 GHz, the wavelength of the optical carrier is 1555 nm and two SOA-EA pairs are concatenated.

Fig. 5.
Fig. 5.

Comparison of experiment and theory. Measured (a) and calculated (b) phase shift as function of EA reverse bias for different input power levels. The solid and dashed lines show the results for two and one SOA-EA pair, respectively. The inset demonstrates the predicted result of concatenating several sections by showing the calculated phase shift for 1, 2, 4 and 8 SOA-EA pairs.

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