Berlin 2008 – scientific programme

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DS: Fachverband Dünne Schichten

DS 6: Semiconductor Nanophotonics: Materials, Models, Devices - High Speed Photonics

DS 6.2: Talk

Monday, February 25, 2008, 10:15–10:30, H 2032

Small-signal cross-gain modulation of quantum dot semiconductor optical amplifiers — •Sven Liebich, Christian Meuer, Matthias Laemmlin, Jungho Kim, and Dieter Bimberg — Institut fuer Festkoerperphysik, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin, Germany

Wavelength conversion based on cross-gain modulation (XGM) of semiconductor optical amplifiers (SOA) is of largest importance for future all optical networks. Using the non-linear gain characteristics of quantum dot (QD) based SOAs this technique will be used for optical signal processing. QD SOAs have shown ultra-fast gain recovery which is superior to quantum well or bulk SOAs [1]. Furthermore in QD SOAs no crosstalk is expected for wavelengths having a difference larger than the homogeneous broadening. To measure the small-signal XGM of QD SOAs a sinusoidally modulated optical pump which saturates the QD SOA is amplified. This results in a modulation of the gain of the amplifier and subsequently superimposes an inverted modulation on a second cw-probe signal. The XGM is measured in the frequency range 50 MHz to 40 GHz with a variation of the operating parameters like SOA current and wavelength detuning. The 3dB-bandwidth of the XGM for optimum operating parameters is observed to exceed 40 GHz. In conclusion, by increasing the drive current the SOA can be modified from low to high cross talk enabling efficient wavelength conversion at high bit rates.

[1] S. Dommers, V. V. Temnov, U. Woggon, J. Gomis, J. Martinez-Pastor, M. Laemmlin and D. Bimberg, APL 90 (2007)