J. Phys. III France
Volume 3, Numéro 5, May 1993
Page(s) 1021 - 1032
DOI: 10.1051/jp3:1993179
J. Phys. III France 3 (1993) 1021-1032

Free-carrier effects in GaAs single modulation-doped quantum well as applied to active Q-switching of injection lasers

V. S. Kalinovsky, T. V. Shubina, I. Yu. Shvechikov and A. A. Toropov

A. F. Ioffe Physico-Technical Institute, Academy of Sciences, 26 Politekhnicheskaya, 194021 St. Petersburg, Russia

(Received 23 January 1992, revised 23 October 1992, accepted 16 February 1993)

Free carrier effects in a modulation-doped GaAs QW placed in the n-region of a p-n junction were successfully used to obtain active Q-switching in a two-section GaAs/A1GaAs DH laser structure. The modulator section uses the blue shift of the QW absorption edge due to band filling by a 2D electron gas whose concentration could be controlled between 0 and $8 \times 10^{11}$ cm -2 by external bias voltage. Only about 100 mV of the modulating voltage was necessary to provide stable active Q-switching. The threshold injection current density ranged from 400 to 800 A/cm 2. The modulation bandwidth is estimated to be not less than 4-5 GHz. A simple electrostatic model is suggested to describe electrooptical phenomena in a modulation-doped QW which underlie the operation of the device.

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