Abstract

It is well known that the semiconductor laser response based on the conventional modulation method by varying the pumping current density (direct modulation) is limited to rather low frequencies. The best results obtained recently for MQW strained layers burried lasers demonstrated a 3-dB bandwidth of about 32 GHz at a wavelength A of 1 μm,¹ and 25 GHz at λ ≈ 1.5 μm² respectively. The main factor, limiting the modulation bandwidth is a very fast 1/f²-like drop of the modulation efficiency at frequencies f exceeding the electron-photon resonance frequency f_res. Analysing the 1/f²-like decay of the laser response, one can conclude, that this characteristic is caused by indirect affect of the pumping current on the high RF laser response. The modulation technique providing slower decay of the laser response was proposed by us e.g. in.³ It is based on the RF controlling of some of the “material'' laser parameters (optical gain, optical confinement factor, photon lifetime, etc.) directly entering the rate equation for photon density. On the base of the rate equation analysis we have shown, that modulating any of these parameters results in a 1/f-like decay of the small-signal laser response, where γ is the damping factor.

© 1995 IEEE