Abstract

Gain and phase dynamics in InAs/GaAs quantum dot semiconductor optical amplifiers are investigated. It is shown that gain recovery is dominated by fast processes, whereas phase recovery is dominated by slow processes. Relative strengths and time constants of the underlying processes are measured. We find that operation at high bias currents optimizes the performance for nonlinear cross-gain signal processing if a low chirp is required.

© 2008 Optical Society of America

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  1. D.  Bimberg, G.  Fiol, M.  Kuntz, C.  Meuer, M.  Laemmlin, N. N. Ledentsov, and A. R.  Kovsh, "High speed nanophotonic devices based on quantum dots," Phys. Status Solidi A 203, 3523-3532 (2006).
    [CrossRef]
  2. T.  Akiyama, H.  Kuwatsuka, T.  Simoyama, Y.  Nakata, K.  Mukai, M.  Sugawara, O.  Wada, and H.  Ishikawa, "Nonlinear gain dynamics in quantum-dot optical amplifiers and its application to optical communication devices," IEEE J. Quantum Electron 37, 1059-1065 (2001).
    [CrossRef]
  3. F.  Lelarge, B.  Dagens, J.  Renaudier, R.  Brenot, A.  Accard, F.  van Dijk, D.  Make, O.  Le Gouezigou, J-G.  Provost, F.  Poingt, J.  Landreau, O.  Drisse, E.  Derouin, B.  Rousseau, F.  Pommereau, and G-H.  Duan, "Recent advances on InAs/InP quantum dash based, semiconductor lasers and optical amplifiers operating at 1.55 μm," IEEE J. Sel. Top. Quantum Electron.  13, 111-124 (2007).
    [CrossRef]
  4. A. J. Zilkie, J.  Meier, P. W. E. Smith, M.  Mojahedi, J. S. Aitchison, P. J. Poole, C. N. Allen, P.  Barrios, and D.  Poitras, "Femtosecond gain and index dynamics in an InAs/InGaAsP quantum dot amplifier operating at 1.55 µm," Opt. Express 14, 11453-11459 (2006).
    [CrossRef] [PubMed]
  5. T.  Piwonski, I.  O’Driscoll, J.  Houlihan, G.  Huyet, and R. J.  Manning and A. V.  Uskov, "Carrier capture dynamics of InAs/GaAs quantum dots," Appl. Phys. Lett. 90, 122108 (2007).
    [CrossRef]
  6. S. Schneider, P. Borri, W. Langbein, U. Woggon, R. L. Sellin, D. Ouyang, and D. Bimberg, "Linewidth enhancement factor in InGaAs quantum-dot amplifiers," IEEE J. Quantum Electron. 40, 1423-1429 (2004).
    [CrossRef]
  7. M. van der Poel, E. Gehrig, O. Hess, D. Birkedal, and J. Hvam, "Ultrafast gain dynamics in quantum-dot amplifiers: Theoretical analysis and experimental investigations," IEEE J. Quantum Electron. 41, 1115-1123 (2005).
    [CrossRef]
  8. M. van der Poel, J. Mork, A. Somers, A. Forchel, J. P. Reithmaier, and G. Eisenstein, "Ultrafast gain and index dynamics of quantum dash structures emitting at 1.55µm," Appl. Phys. Lett. 89, 081102 (2006).
    [CrossRef]
  9. K. L.  Hall, G.  Lenz, A. M.  Darwish, and E. P.  Ippen, "Subpicosecond gain and index nonlinearities in InGaAsP diode lasers," Opt. Commun. 111, 589-612 (1994).
    [CrossRef]
  10. A. V.  Uskov, E. P.  O’Reilly, M.  Laemmlin, N. N.  Ledentsov, and D.  Bimberg, "On gain saturation in quantum dot semiconductor optical amplifiers," Opt. Commun 248, 211-219 (2005).
    [CrossRef]
  11. A. Uskov, E. O’Reilly, R. Manning, R. Webb, D. Cotter, M. Laemmlin, N. Ledentsov, and D. Bimberg, "On ultrafast optical switching based on quantum-dot semiconductor optical amplifiers in nonlinear Interferometers," IEEE Photonics Technol. Lett. 16, 1265-1267 (2004).
    [CrossRef]
  12. J.  Wang, A.  Maitra, C. G.  Poulton, W.  Freude, and J.  Leuthold, "Temporal dynamics of the alpha factor in semiconductor optical amplifiers," J. Lightwave Technol. 25, 891-900 (2007).
    [CrossRef]
  13. J. Wang, A. Maitra, W. Freude, and J. Leuthold, " Regenerative properties of interferometric cross-gain and cross-phase modulation DPSK wavelength converters," in Nonlinear Photonics, OSA Technical Digest (CD) (Optical Society of America, 2007), paper NTuB2. http://www.opticsinfobase.org/abstract.cfm?URI=NP-2007-NTuB2

2007 (3)

T.  Piwonski, I.  O’Driscoll, J.  Houlihan, G.  Huyet, and R. J.  Manning and A. V.  Uskov, "Carrier capture dynamics of InAs/GaAs quantum dots," Appl. Phys. Lett. 90, 122108 (2007).
[CrossRef]

F.  Lelarge, B.  Dagens, J.  Renaudier, R.  Brenot, A.  Accard, F.  van Dijk, D.  Make, O.  Le Gouezigou, J-G.  Provost, F.  Poingt, J.  Landreau, O.  Drisse, E.  Derouin, B.  Rousseau, F.  Pommereau, and G-H.  Duan, "Recent advances on InAs/InP quantum dash based, semiconductor lasers and optical amplifiers operating at 1.55 μm," IEEE J. Sel. Top. Quantum Electron.  13, 111-124 (2007).
[CrossRef]

J.  Wang, A.  Maitra, C. G.  Poulton, W.  Freude, and J.  Leuthold, "Temporal dynamics of the alpha factor in semiconductor optical amplifiers," J. Lightwave Technol. 25, 891-900 (2007).
[CrossRef]

2006 (3)

A. J. Zilkie, J.  Meier, P. W. E. Smith, M.  Mojahedi, J. S. Aitchison, P. J. Poole, C. N. Allen, P.  Barrios, and D.  Poitras, "Femtosecond gain and index dynamics in an InAs/InGaAsP quantum dot amplifier operating at 1.55 µm," Opt. Express 14, 11453-11459 (2006).
[CrossRef] [PubMed]

M. van der Poel, J. Mork, A. Somers, A. Forchel, J. P. Reithmaier, and G. Eisenstein, "Ultrafast gain and index dynamics of quantum dash structures emitting at 1.55µm," Appl. Phys. Lett. 89, 081102 (2006).
[CrossRef]

D.  Bimberg, G.  Fiol, M.  Kuntz, C.  Meuer, M.  Laemmlin, N. N. Ledentsov, and A. R.  Kovsh, "High speed nanophotonic devices based on quantum dots," Phys. Status Solidi A 203, 3523-3532 (2006).
[CrossRef]

2005 (2)

A. V.  Uskov, E. P.  O’Reilly, M.  Laemmlin, N. N.  Ledentsov, and D.  Bimberg, "On gain saturation in quantum dot semiconductor optical amplifiers," Opt. Commun 248, 211-219 (2005).
[CrossRef]

M. van der Poel, E. Gehrig, O. Hess, D. Birkedal, and J. Hvam, "Ultrafast gain dynamics in quantum-dot amplifiers: Theoretical analysis and experimental investigations," IEEE J. Quantum Electron. 41, 1115-1123 (2005).
[CrossRef]

2004 (2)

A. Uskov, E. O’Reilly, R. Manning, R. Webb, D. Cotter, M. Laemmlin, N. Ledentsov, and D. Bimberg, "On ultrafast optical switching based on quantum-dot semiconductor optical amplifiers in nonlinear Interferometers," IEEE Photonics Technol. Lett. 16, 1265-1267 (2004).
[CrossRef]

S. Schneider, P. Borri, W. Langbein, U. Woggon, R. L. Sellin, D. Ouyang, and D. Bimberg, "Linewidth enhancement factor in InGaAs quantum-dot amplifiers," IEEE J. Quantum Electron. 40, 1423-1429 (2004).
[CrossRef]

2001 (1)

T.  Akiyama, H.  Kuwatsuka, T.  Simoyama, Y.  Nakata, K.  Mukai, M.  Sugawara, O.  Wada, and H.  Ishikawa, "Nonlinear gain dynamics in quantum-dot optical amplifiers and its application to optical communication devices," IEEE J. Quantum Electron 37, 1059-1065 (2001).
[CrossRef]

1994 (1)

K. L.  Hall, G.  Lenz, A. M.  Darwish, and E. P.  Ippen, "Subpicosecond gain and index nonlinearities in InGaAsP diode lasers," Opt. Commun. 111, 589-612 (1994).
[CrossRef]

Appl. Phys. Lett. (2)

T.  Piwonski, I.  O’Driscoll, J.  Houlihan, G.  Huyet, and R. J.  Manning and A. V.  Uskov, "Carrier capture dynamics of InAs/GaAs quantum dots," Appl. Phys. Lett. 90, 122108 (2007).
[CrossRef]

M. van der Poel, J. Mork, A. Somers, A. Forchel, J. P. Reithmaier, and G. Eisenstein, "Ultrafast gain and index dynamics of quantum dash structures emitting at 1.55µm," Appl. Phys. Lett. 89, 081102 (2006).
[CrossRef]

IEEE J. Quantum Electron (1)

T.  Akiyama, H.  Kuwatsuka, T.  Simoyama, Y.  Nakata, K.  Mukai, M.  Sugawara, O.  Wada, and H.  Ishikawa, "Nonlinear gain dynamics in quantum-dot optical amplifiers and its application to optical communication devices," IEEE J. Quantum Electron 37, 1059-1065 (2001).
[CrossRef]

IEEE J. Quantum Electron. (2)

S. Schneider, P. Borri, W. Langbein, U. Woggon, R. L. Sellin, D. Ouyang, and D. Bimberg, "Linewidth enhancement factor in InGaAs quantum-dot amplifiers," IEEE J. Quantum Electron. 40, 1423-1429 (2004).
[CrossRef]

M. van der Poel, E. Gehrig, O. Hess, D. Birkedal, and J. Hvam, "Ultrafast gain dynamics in quantum-dot amplifiers: Theoretical analysis and experimental investigations," IEEE J. Quantum Electron. 41, 1115-1123 (2005).
[CrossRef]

IEEE J. Sel. Top. Quantum Electron. (1)

F.  Lelarge, B.  Dagens, J.  Renaudier, R.  Brenot, A.  Accard, F.  van Dijk, D.  Make, O.  Le Gouezigou, J-G.  Provost, F.  Poingt, J.  Landreau, O.  Drisse, E.  Derouin, B.  Rousseau, F.  Pommereau, and G-H.  Duan, "Recent advances on InAs/InP quantum dash based, semiconductor lasers and optical amplifiers operating at 1.55 μm," IEEE J. Sel. Top. Quantum Electron.  13, 111-124 (2007).
[CrossRef]

IEEE Photonics Technol. Lett. (1)

A. Uskov, E. O’Reilly, R. Manning, R. Webb, D. Cotter, M. Laemmlin, N. Ledentsov, and D. Bimberg, "On ultrafast optical switching based on quantum-dot semiconductor optical amplifiers in nonlinear Interferometers," IEEE Photonics Technol. Lett. 16, 1265-1267 (2004).
[CrossRef]

J. Lightwave Technol. (1)

Opt. Commun (1)

A. V.  Uskov, E. P.  O’Reilly, M.  Laemmlin, N. N.  Ledentsov, and D.  Bimberg, "On gain saturation in quantum dot semiconductor optical amplifiers," Opt. Commun 248, 211-219 (2005).
[CrossRef]

Opt. Commun. (1)

K. L.  Hall, G.  Lenz, A. M.  Darwish, and E. P.  Ippen, "Subpicosecond gain and index nonlinearities in InGaAsP diode lasers," Opt. Commun. 111, 589-612 (1994).
[CrossRef]

Opt. Express (1)

Phys. Status Solidi A (1)

D.  Bimberg, G.  Fiol, M.  Kuntz, C.  Meuer, M.  Laemmlin, N. N. Ledentsov, and A. R.  Kovsh, "High speed nanophotonic devices based on quantum dots," Phys. Status Solidi A 203, 3523-3532 (2006).
[CrossRef]

Other (1)

J. Wang, A. Maitra, W. Freude, and J. Leuthold, " Regenerative properties of interferometric cross-gain and cross-phase modulation DPSK wavelength converters," in Nonlinear Photonics, OSA Technical Digest (CD) (Optical Society of America, 2007), paper NTuB2. http://www.opticsinfobase.org/abstract.cfm?URI=NP-2007-NTuB2

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Figures (8)

Fig. 1.
Fig. 1.

Schematic of the heterodyne pump-probe setup [4]. Short pulses are generated by an optical parametric oscillator (OPO) and split into pump, probe and reference pulses in a polarizing beam splitter (PBS). Probe and reference pulses are tagged by a frequency shift f prb and f ref, respectively, which is induced by acousto-optic modulators (AOM). A strong pump pulse drives the SOA into its nonlinear regime and can be attenuated by the combination of the half-wave plate and the second polarizing beam splitter. A weak pulse probes these nonlinearities in gain and phase. After the device under test (DUT), the pulse train is split and recombined in a Michelson interferometer with unbalanced arm lengths such that the resulting probe-reference beat signal with frequency f ref-f prb can be detected in amplitude and phase by a lock-in amplifier.

Fig. 2.
Fig. 2.

(a) Pump spectrum and ASE without optical pump (different intensity scales.) Ground state and excited state are marked by GS and ES, respectively. (b) Gain suppression measured under pump probe conditions. In the fiber before the SOA, we measured an input power of -11.5 dBm (-15.5 dBm) for a 3 dB (1 dB) gain compression. This corresponds to a pulse energy of 0.89 pJ (0.35 pJ).

Fig. 3.
Fig. 3.

Time evolution of (a) gain suppression G/G 0 and (b) phase dynamics of a typical QD SOA device for a bias current density of i=1.25 kA/cm2. The fit (solid line) well reproduces the measured data (gray dots). The model assumes a fast process (dashed line), a slow process (long-dashed line) and instantaneous two-photon absorption (TPA, dash-dotted line).

Fig. 4.
Fig. 4.

Dependence of time constants on (a) pump power and (b) bias current density for fast and slow processes. Both processes show only a weak dependence on input power. The time constant of the fast process is τ1<10 ps and of the slow process 100ps<τ2<500 ps. The pump power dependence was measured at a bias current density of i=1.25 kA/cm2 and the bias current dependence with pump powers of -6 dBm (open symbols) and -11 dBm (filled symbols). The inset shows the power law of the bias current density dependence of the time constant of the fast process on doubly logarithmic scales.

Fig. 5.
Fig. 5.

Change of (a) net gain ΓLΔg 1,2 and (b) phase Δφ 1,2=-k 0ΓLΔn 1,2 as a function of pump power and bias current density. The strength of the response increases with input power. The slow process has a weak effect on the gain, but influences the phase as strongly as the fast process.

Fig. 6.
Fig. 6.

(a) Ratio of strengths of fast and slow processes for phase (Δφ 1φ 2) and gain (Δg1/Δg2) and of (b) alpha-factors for the fast (2Δφ 1g 1) and the slow processes (2Δφ 2g 2) as a function of input power and bias current density. The material gain response is dominated by the fast process. The phase response is only weakly influenced by the input power but both processes are of equal strength. In (b) it is seen that the fast process has a very low alpha-factor α H<1 that changes for large parameter variations by a factor of 2 only. The slow process has an alpha-factor of 1<α H<22 that strongly increases with the bias current density.

Fig. 7.
Fig. 7.

Effective time dependent alpha-factors α eff(t) (solid line) and αint (t) (dashed line) for the traces shown in Fig. 3. The dynamic response of the first 10 ps is governed by the fast process with an alpha-factor close to zero. Later, the slow process with a large alpha-factor dominates.

Fig. 8.
Fig. 8.

Dependence of effective 90/10 recovery time of chip gain and phase on input power and bias current density. The phase recovery is dominated by the slow process. The gain recovery is fastest for low input power and high current densities and might be sped up by very strong input powers.

Equations (7)

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Δ g ( t ) = u ( t ) [ Δ g 1 exp { t τ 1 } + Δ g 2 exp { t τ 2 } ] + Δ g TPA δ ( t )
Δ n ( t ) = u ( t ) [ Δ n 1 exp { t τ 1 } + Δ n 2 exp { t τ 2 } ] ,
T ( τ ) = F ( 2 ) ( τ t ) exp { Γ L ( Δ g ( t ) 2 j k 0 Δ n ( t ) ) } d t ,
τ 1 i β , β = 0.5 ± 0.1 ,
α 1 , 2 = 4 π λ ( Δ n 1 , 2 exp ( t τ 1 , 2 ) ) t ( Δ g 1 , 2 exp t τ 1 , 2 ) t = 4 π λ Δ n 1 , 2 Δ g 1 , 2 = 2 Δ φ 1 , 2 Δ g 1 , 2 .
α eff ( t ) = 4 π λ ( Δ n ( t ) ) t ( Δ g ( t ) ) t = 2 ( Δ φ ( t ) ) t ( Δ g ( t ) ) t .
α int ( t ) = 4 π λ Δ n ( t ) Δ g ( t ) = 2 Δ φ ( t ) Δ g ( t ) .

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