Polarization-independent dual-band optical modulation via strongly coupled optical Tamm states at 1D photonic crystal heterointerfaces

Abstract

Here, we theoretically studied the strong longitudinal coupling of two optical Tamm states (OTS) in one-dimensional (1D) photonic crystal heterostructures embedded with lithium niobate (LN) layers in the near-infrared band. It is found that the two optical Tamm states can strongly interact with one another in the out-of-plane direction, enabling a large Rabi splitting (∼3.1 meV) in spectral response. The hybrid modes have an ultra-narrow linewidth of 0.85 nm with a Q factor up to 2.2 × 10³. The hybridization of two OTSs was investigated by calculating field profiles and Hopfield coefficients of hybrid modes. The simulation results show that the resonant frequencies of two OTSs can be flexibly controlled by changing the structural parameters or dynamically modulating the gate voltage on the LN layers to reach zero-detuning for strong coupling generation. Remarkably, we reveal that resonant frequencies of the hybrid modes are extremely sensitive to the gate voltage on LN films while immune to the polarization of normally incident light, enabling a dual-band electro-optic (EO) modulation with an ultra-high sensitivity (0.13 nm/V) and nearly perfect modulation depth (∼99 %). The polarization-independent, dual-band, highly efficient optical modulation offered by the hybrid modes in this etchless multilayer structure can find potential applications in multi-channel light detecting, multispectral nanolasing, tunable filtering, and optical modulation devices.