Electric-field effects on intersubband Raman laser gain in modulation-doped GaAs/AlGaAs coupled double quantum wells

We study numerically the electric-field effects on optically pumped mid-infrared intersubband Raman lasers (IRL) consisting of modulation-doped GaAs/AlGaAs asymmetric coupled double quantum wells. The collective plasmon nature of intersubband excitations is important to analyze the characteristics of IRL gain. The lasing wavelength is changed from 15.0 to 12.5 μm by increasing applied bias from K40 to 10 kV/cm for pumping wavelength 9.56 μm with intensity 250 kW/cm2 if the maximum gain at threshold was assumed to be 100 cm-1, α and Γopt being total radiation loss and optical confinement factor, respectively.