CONTRASTACIÓN DE LOS RESULTADOS DEL TRABAJO DE CAMPO CON LOS REFERENTES

A thorough characterisation of the mode-locking regime in several QD lasers was performed. The pulses generated were relatively long (>2ps), despite the wide spectral bandwidth available. The TBWP was significantly higher than the Fourier limit, particularly due to the effects of SPM in the gain section and inhomogeneous broadening of the gain, which increase with increasing current. Indeed, the effect of the bias conditions on the duration and power of the pulses shows that the limitation in achieving simultaneously high output power and short pulses restricts the achievable output peak power. The pulses are found to be shorter in the bias region close to threshold and at high reverse bias values; however, the average power is at its lowest in this range of conditions. Higher power levels seem difficult to attain while in mode-locked operation, as increasingly large contributions from SPM and dispersion make the mode-locking regime become less stable and eventually collapse. The detrimental role of SPM with increasing current is linked to a high LEF observed in QD lasers.

3.6.

References

[1] U2t Photonics: www.u2t.de.

[2] Hamamatsu: http://jp.hamamatsu.com.

[3] E. U. Rafailov, M. A. Cataluna, W. Sibbett, N. D. Il'inskaya, Y. M. Zadiranov, A. E. Zhukov, V. M. Ustinov, D. A. Livshits, A. R. Kovsh, and N. N. Ledentsov, "High-power picosecond and femtosecond pulse generation from a two-section mode-locked quantum-dot laser," Appl. Phys. Lett., vol. 87, pp. 81107-3, 2005.

[4] E. P. Ippen and C. V. Shank, "Techniques for Measurement," in Ultrashort Light Pulses, S. L. Shapiro, Ed. New York: Springer, 1977, pp. 83-122.

[5] J. H. Chung and A. M. Weiner, "Ambiguity of ultrashort pulse shapes retrieved from the intensity autocorrelation and the power spectrum," IEEE J. Sel. Topics Quantum Electron., vol. 7, pp. 656-666, 2001.

[6] Z. A. Yasa and N. M. Amer, "A rapid-scanning autocorrelation scheme for continuous monitoring of picosecond laser pulses," Opt. Commun., vol. 36, pp. 406-408, 1981.

[7] P. Vasil'ev, Ultrafast Diode Lasers: Fundamentals and Applications. Boston: Artech House, 1995.

[8] G. P. Agrawal and N. A. Olsson, "Self-Phase Modulation and Spectral Broadening of Optical Pulses in Semiconductor-Laser Amplifiers," IEEE J. Quantum Electron., vol. 25, pp. 2297-2306, 1989.

[9] M. Y. Hong, Y. H. Chang, A. Dienes, J. P. Heritage, P. J. Delfyett, S. Dijaili, and F. G. Patterson, "Femtosecond self- and cross-phase modulation in semiconductor laser amplifiers," IEEE J. Sel. Topics Quantum Electron., vol. 2, pp. 523-539, 1996.

[10] M. T. Choi, W. Lee, J. M. Kim, and P. J. Delfyett, "Ultrashort, high-power pulse generation from a master oscillator power amplifier based on external cavity mode locking of a quantum-dot two-section diode laser," Appl. Phys. Lett., vol. 87, pp. 221107-3, 2005.

[11] M. Kuntz, G. Fiol, M. Lammlin, D. Bimberg, M. G. Thompson, K. T. Tan, C. Marinelli, R. V. Penty, I. H. White, V. M. Ustinov, A. E. Zhukov, Y. M. Shernyakov, and A. R. Kovsh, "35 GHz mode-locking of 1.3 µm

quantum dot lasers," Appl. Phys. Lett., vol. 85, pp. 843-845, 2004.

[12] M. Gioannini, A. Sevega, and I. Montrosset, "Simulations of differential gain and linewidth enhancement factor of quantum dot semiconductor lasers,"

Opt. Quantum Electron., vol. 38, pp. 381-394, 2006.

[13] S. Melnik and G. Huyet, "The linewidth enhancement factor alpha of quantum dot semiconductor lasers," Opt. Express, vol. 14, pp. 2950-2955, 2006.

[14] A. Martinez, A. Lemaitre, K. Merghem, L. Ferlazzo, C. Dupuis, A. Ramdane, J. G. Provost, B. Dagens, O. Le Gouezigou, and O. Gauthier-Lafaye, "Static and dynamic measurements of the alpha-factor of five-quantum-dot-layer single-mode lasers emitting at 1.3 µm on GaAs," Appl. Phys. Lett., vol. 86, pp. 211115, 2005.

[15] H. Su and L. F. Lester, "Dynamic properties of quantum dot distributed feedback lasers: high speed, linewidth and chirp," J. Phys. D, vol. 38, pp. 2112-2118, 2005.

[16] P. J. Delfyett, "Ultrafast Single and Multiwavelength Modelocked Semiconductor Lasers: Physics and Applications," in Ultrafast Lasers - Technology and Applications, M. E. Fermann, A. Galvanauskas, and G. Sucha, Eds. New York: Marcel Dekker, Inc., 2003, pp. 219-321.

[17] M. G. Thompson, A. Rae, R. L. Sellin, C. Marinelli, R. V. Penty, I. H. White, A. R. Kovsh, S. S. Mikhrin, D. A. Livshits, and I. L. Krestnikov, "Subpicosecond high-power mode locking using flared waveguide monolithic quantum-dot lasers," Appl. Phys. Lett., vol. 88, pp. 133119-3, 2006.

[18] D. B. Malins, A. Gomez-Iglesias, S. J. White, W. Sibbett, A. Miller, and E. U. Rafailov, "Ultrafast electroabsorption dynamics in an InAs quantum dot saturable absorber at 1.3 µm," Appl. Phys. Lett., vol. 89, pp. 171111-3, 2006. [19] K. Yvind, P. M. W. Skovgaard, J. Mork, A. J. Hanberg, and A. M. Kroh,

"Performance of External Cavity Mode-Locked Semiconductor Lasers Employing Reverse Biased Saturable Absorbers," Physica Scripta, vol. 101, pp. 129-132, 2002.

[20] M. G. Thompson, K. T. Tan, C. Marinelli, K. A. Williams, R. V. Penty, I. H. White, M. Kuntz, D. Ouyang, D. Bimberg, V. M. Ustinov, A. E. Zhukov, A. R. Kovsh, N. N. Ledentsov, D. J. Kang, and M. G. Blamire, "Transform-limited optical pulses from 18 GHz monolithic modelocked quantum dot lasers operating at 1.3 µm," Electron. Lett., vol. 40, pp. 346-347, 2004.

[21] M. G. Thompson, C. Marinelli, Y. Chu, R. L. Sellin, R. V. Penty, I. H. White, M. Van Der Peol, D. Birkedal, J. Hvam, V. M. Ustinov, M. Lammlin, and D. Bimberg, "Properties of InGaAs quantum dot saturable absorbers in monolithic mode-locked lasers," IEEE 19th International Semiconductor Laser Conference, 53-54, Matsue Shi, Japan, 2004.

[22] M. Laemmlin, G. Fiol, C. Meuer, M. Kuntz, F. Hopfer, A. R. Kovsh, N. N. Ledentsov, and D. Bimberg, "Distortion-free optical amplification of 20- 80 GHz modelocked laser pulses at 1.3 µm using quantum dots," Electron. Lett., vol. 42, pp. 697-699, 2006.

[23] L. Harris, D. J. Mowbray, M. S. Skolnick, M. Hopkinson, and G. Hill, "Emission spectra and mode structure of InAs/GaAs self-organized quantum dot lasers," Appl. Phys. Lett., vol. 73, pp. 969-971, 1998.