We analyze the occurrence of normal-mode coupling (NMC) in bimodal lasers attributed to the collective interaction of the cavity field with a mesoscopic number of quantum dots (QDs). In contrast to the conventional NMC, here we observe locking of the frequencies and splitting of the linewidths of the system's eigenmodes in the coherent coupling regime. The theoretical analysis of the incoherent regime is supported by experimental observations where the emission spectrum of one of the orthogonally polarized modes of a bimodal QD micropillar laser demonstrates a distinct two-peak structure.Introduction. The study of cavity quantum electrodynamics (CQED) in the strong-coupling regime between atomlike emitters and the confined light field of microcavities has been a subject of considerable attention. In the traditional CQED, low-mode volume resonators are used to enhance the coupling rate g between a single emitter and the field in comparison to the system damping rates. Prominent realizations of the strong coupling include experimental demonstrations of reversible exchange of excitation between a single emitter and the field from both atomic [1-3] and solid-state [4,5] systems. Typical evidence of the strong-coupling regime represents splitting of the two degenerate modes, i.e., normal-mode splitting, which is a consequence of normal-mode coupling (NMC), e.g., between the emitter polarization mode and the field mode leading to a doublet cavity transmission spectrum [6[. In addition, NMC occurs in exciton-photon and phonon-photon interactions [7] and optomechanical phenomena [8], where the cavity field couples to a mechanical mode [9[. In view of the variety of implications of the regime of coherent coupling (see, e.g., [10]), a different approach to achieve strong coupling has also attracted much attention. Instead of reducing the cavity-mode volume to achieve large g, the number of emitters N interacting with the field can be increased, leading to the collective strong-coupling regime, where the coupling rate scales as V N g [11,12]. Various experimental observations of cavity-mode spectra proportional to \/~Ng due to the collective coherent coupling with two [13,14] or multiple [15,16] emitters have been made, including the case of a multimode cavity [17], In solid-state systems, the coherent coupling between a cavity mode and an ensemble of emitters has been achieved in the classical regime with semiconductor quantum wells [7,18]. However, in the quantum regime the significant inhomogeneous broadening of emission from self-assembled quantum dots (QDs) has so far hindered the observation of collective coherent coupling for semiconductor-based quantum emitters.