Studies have been carried out of emission characteristics directly related to the mode composition of radiation, such as the spatial distribution of radiation and generation spectra of lasers with a radiation aperture of 20 μm and different cavity lengths, made on the basis of an AlGaInAs/InP heterostructure with an ultra-narrow waveguide. It is shown that there are two ranges of pump currents in which the laser characteristics behave differently. The first range of currents corresponds to operation in a few-mode mode and switching between modes; the characteristics of each individual sample have a strong influence on mode competition, which leads to a spread of characteristics between identical samples in this region. In the second range, the laser operates in a multimode lasing mode: the spread of characteristics between samples practically degenerates.