Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 86: Semiconductor Lasers

HL 86.2: Talk

Thursday, March 29, 2012, 15:15–15:30, EW 015

Absorption Spectra and Modulation Response of a Quantum Dot Laser Device With Integrated Electro-Optic Modulator — •Miriam Wegert, Kathy Lüdge und Eckehard Schöll — TU Berlin, Institut für Theoretische Physik, Berlin, Germany

In this work we theoretically study the influence of modulator voltage, optical input and band structure on the absorption spectrum and the small-signal modulation response of a quantum dot (QD) electrooptic modulator (EOM) and investigate the dynamics of a laser device with integrated EOM.

Our theoretical model is based upon semiconductor Bloch equations which describe the coupled polarization and population dynamics and a traveling wave field equation. The impact of the quantum confined Stark effect, a red shift of the wavelength of the optical transition and a decrease of the oscillator strength through the shift of the energy levels and the distortion of the wave functions when a voltage is applied to the modulator, is included in the model.

Our simulations show that it is crucial both to include the QD excited state and to distinguish between electrons and holes to describe the absorption recovery properly. The absorption recovery time can be optimized by tuning the energy spacing. That makes a laser device with integrated EOM an excellent candidate for switching applications in an optical communication system. The simulated absorption spectra as well as the small-signal modulation response are in good agreement with experimental results.