Theoretical optimization of inhomogeneous broadening in InGaN/GaN MQWs to polariton splitting at low temperature

Exciton-photon interaction in strong coupling region is an interesting topic in exploring bosonic physics and devices. Until now, however, InGaN based exciton polariton was rarely reported since its large inhomogeneous broadening. In this study, the impact of inhomogeneous broadening Gamma(inh) of InGaN/GaN quantum wells (QWs) on the normal mode energy splitting Omega(NMS), between the upper and lower polariton branches was theoretically analyzed by transfer matrix method and linear nonlocal dispersion model. Surprisingly, an optimal inhomogeneous broadening Gamma(opt), corresponding to the maximum value of Omega(NMS) was deprived at low temperature, which has not been reported before. The effect of Gamma(inh) was divided into two regions for explaining the existence of Gamma(opt). Meanwhile, the Gamma(opt) was found to be strongly correlated with the oscillator strength and homogeneous broadening.