CALCULATION OF DIFFERENTIAL GAIN AND LINEWIDTH ENHANCEMENT FACTOR IN 980-NM INGAAS VERTICAL-CAVITY SURFACE-EMITTING

The optimization of differential gain and linewidth enhancement factor within VCSEL's is required to achieve improved performance under dyna mic conditions. In this paper, the differential gain and linewidth enh ancement factor in an InGaAs-GaAs VCSEL have been calculated over a ra nge of carrier densities and at various wavelengths across the gain sp ectrum. The results show the importance of low threshold gain values i n achieving high differential gain/low linewidth enhancement factor. B y temperature tuning the lasing wavelength to shorter wavelengths than the gain peak, values of alpha(H) its low as 0.6 can be achieved.