Confinement of electrons and holes is assumed to take place within the quantum well of a laser diode for all modes of operation of the diode. Photons are expected to be confined within the Fabry–Perot cavity with little spreading out of the resonator. After it was established that the quasi-Fermi (QF) profile across an operational laser defines the concentration of carriers in a quantum well, this new study was initiated in order to establish correlation between the shape of the QF profile and the degree of optical and current confinement. The quantum well based laser diodes consist of p- and n-doped layers of Al0.6Ga0.4As sandwiching two undoped layers of Al025Ga0.75As 0.16 μm thick which, in turn, surround two layers of 150 Å GaAs in which the 110 Å In0.2Ga0.8As quantum well is encased. This structure was mounted in a scanning electron microscope (SEM), and differential voltage contrast (DVC) was used to measure QF profiles while intensity of emission was measured by a specially calibrated photoamplifier. We observed very high peaks of QF energy, which could be explained on the basis of photon interaction with hole and electron gasses. In the current study, we were able to assess, in-situ, the QF profile for the population inversion, the threshold of laser operation, and full emission, as well as the degree of confinement at these stages of laser diode operation.