Souissi, H.; Gromovyi, M.; Septembre, I.; Develay, V.; Brimont, C.; Doyennette, L.; Cambril, E.; Bouchoule, S.; Alloing, B.; Frayssinet, E.; Zuniga-Perez, J.; Ackemann, T.; Malpuech, G.; Solnyshkov, D. D.; Guillet, T. Mode-locked waveguide polariton laser; OPTICA 11, 962 (2024),
https://doi.org/10.1364/OPTICA.524753
So far, exciton-polariton (polariton) lasers were mostly single-mode lasers based on microcavities. Despite the large repulsive polariton-polariton interaction, a pulsed mode-locked polariton laser was never, to our knowledge, reported. Here, we use a 60-µm-long GaN-based waveguide surrounded by distributed Bragg reflectors forming a multi-mode horizontal cavity. We demonstrate experimentally and theoretically a polariton mode-locked micro-laser operating in the blue-UV, at room temperature, with a 300 GHz repetition rate and 100-fs-long pulses. The mode-locking is demonstrated by the compensation (linearization) of the mode dispersion by the self-phase modulation induced by the polariton-polariton interaction. It is also supported by the observation in experiment and theory of the typical envelope frequency profile of a bright soliton.