Unlocking Optical Coupling Tunability in Epsilon‐Near‐Zero Metamaterials Through Liquid Crystal Nanocavities

Epsilon-near-zero (ENZ) metamaterials represent a powerful toolkit for selectively transmitting and localizing light through cavity resonances, enabling the study of mesoscopic phenomena and facilitating the design of photonic devices. In this experimental study, it demonstrates the feasibility of engineering and actively controlling cavity modes, as well as tuning their mutual coupling, in an ENZ multilayer structure. Specifically, by employing a high-birefringence liquid crystal film as a tunable nanocavity, the polarization-dependent coupling of resonant modes with narrow spectral width and spatial extent is achieved. Surface forces apparatus (SFA) allowed to continuously and precisely control the thickness of the liquid crystal (LC) film contained between the nanocavities and thus vary the detuning between the cavity modes. Hence, it is able to manipulate nanocavities anti-crossing behaviors. The suggested methodology unlocks the full potential of tunable optical coupling in epsilon-near-zero metamaterials and provides a versatile approach to the creation of tunable photonic devices, including bio-photonic sensors and/or tunable planar metamaterials for on-chip spectrometers.A high birefringence liquid crystal (Delta n approximate to 0.4) is squeezed between two epsilon near zero metamaterials forming a nanocavity whose thickness is dynamically varied through surface force apparatus. This allows confining the electric field and correlated modes at different wavelengths. Furthermore, the anti-cross behavior is highlighted by varying the cavity thickness or switching the LC refractive index changing the input light polarization.image