Active Phase and Amplitude Modulation in Perovskite Polaritonic Waveguides

Integrated photonic technologies require active materials capable of providing large optical modulation within compact footprints and low losses. The large optical nonlinearities of exciton-polaritons offer a promising route to meet these requirements, yet their integration into photonic circuits remains challenging because strong light-matter interactions must be combined with low-loss transport and spatially localized control. Here, we demonstrate active phase and amplitude modulation in halide perovskite polaritonic waveguides integrated with electrical microheaters. Local electrothermal actuation drives a structural phase transition in the perovskite, modifying the complex refractive index dispersion near the excitonic resonance. By tuning the excitonic fraction of the propagating mode, the waveguides can therefore operate either as a phase shifter with a tuning efficiency of 0.2 mW mm, approximately one order of magnitude lower than silicon modulators with similar geometries, or as an intensity switch , providing 1 dB/um modulation depth at 20 mW. Our work establishes phase-change excitonic reconfiguration as a route towards compact polariton circuits for nonlinear photonic applications.