Figure 3. Reflectivity scans showing strong coupling for X⁰ and weak coupling for X⁻.

(a) Reflectivity scan of a single-QW area at 4 K showing clear anticrossing with X⁰. Weak coupling with X⁻ is also apparent where the coupling strength is less than the charged exciton linewidth. (b) Theoretical reproduction of a based on a three-coupled oscillator model with coupling strengths of 18 and 8.2 meV for X⁰ and X⁻, respectively. (c) Reflectivity scan of an empty cavity with no active region showing a linear dependence of the cavity mode energy on the piezo voltage.