Overcoming angular dispersion in optical microcavities and filters by ultra-strong light-matter coupling with organic materials

Thin film interference is essential in optoelectronic devices, impacting all spectral characteristics such as emission, transmission, or absorption profiles. However, photonic systems relying on optical thin films fundamentally face blue shifts at non-normal angles of incidence. We address this issue by utilizing ultra-strong coupling between cavity photons and material excitons, transitioning the photonic to a flat exciton-like dispersion. This technique is especially effective when using organic materials with high oscillator strengths and enables angle-independent, narrowband responses. We demonstrate both narrowband and broadband, angle-independent transmission filters in metallic cavities and are able to generalize this enhanced performance to distributed Bragg reflector-like dielectric stacks. Additionally, we develop polaritonic narrowband photodetectors and organic LEDs [1] with minimal dispersion. This approach benefits micro-optics, biophotonics, and other fields addressing light collimation challenges, demonstrating the practical utility of strong coupling in creating spectrally stable optoelectronic devices.