Estimation of linewidth enhancement factor of AlGaAs lasers by correlation measurement between FM and AM noises

A novel method for estimating the linewidth enhancement factor α of semiconductor lasers has been developed. In this method, the spectrum of the correlation between FM and AM noises is measured in a frequency range where the spontaneous emission noise is dominant, and then the α value is calculated from the measured correlation. The α value of channeled-substrate-planar AlGaAs lasers has been estimated to be 2.2-2.8.