Polariton laser based on GaN waveguide: towards micrometer-long lasers

Hassen Souissi

L2C -

We demonstrate how a ridge polariton laser is different from a standard ridge laser. We investigate the effect of the optical pumping length, i.e. the size of the exciton reservoir, versus the cavity length by exciting the waveguide with a variable line-shaped pump spot matching the ridge, at 355nm, resonant with the exciton reservoir. We prove that the laser effect is achieved even for an excitation length of just 10% of the cavity, with only a threefold increase of the overall threshold. However, for conventional lasers, it would have been necessary to excite more than half of the cavity in order to obtain the laser effect due to the reciprocity between absorption and stimulated emission, highlighting the specific lasing process involved in polariton lasers. Moreover, we assess the strong coupling regime between excitons and guided photons in a GaN waveguide.