Table 1.

Description of the membranes used in this study.

Name	Membrane thickness	Type of measurement
Membrane 1	≈206 nm	All basic optical characterization, including temperature dependence and estimation of Rabi splitting
Membrane 2	≈200 nm	Confirmation of MPB dispersion at lower temperatures
Membrane 3	≈201 nm	Confirmation of the determined Rabi splitting
Membrane 4	≈217 nm	Confirmation of the determined Rabi splitting
Membrane 5	Two regions with varying thickness of 205 nm and 202 nm.	Nonlinear and polariton lasing measurements