A detailed noise study of mid-infrared 2–3 μm wavelenght GaSb-based type-I ridge-waveguide laser diodes (LDs) has been carried out using the low frequency noise spectroscopy. Different samples having slightly different heterostructures, differently packaged, with and without facet passivation have been investigated. The activation energies of trap levels, associated with additional generation-recombination (g–r) noise components in noise spectra at small current region before the threshold, have been determined. It was shown that at particular forward currents the mode-hopping effect dominates during LD lasing operation. It was demonstrated that small differences in LD heterostructure and waveguide layers have got the largest influence to LD noise characteristics while influence of the absence of facet passivation, linking to noise generation centers at the cleaved semiconductor interface, and package type is much weaker.