Manipulation of chirality dependent nonlinear optical effect in 2D halide perovskite under light-matter strong coupling

The introduction of chirality into organic–inorganic hybrid perovskites is expected to achieve excellent optoelectronic and spintronic applications, correlated with circular polarized light. Owing to the existence of asymmetric center and induced intrinsic chirality in the chiral perovskite, chirality dependent second harmonic generation (SHG), so-called CD (circular dichroism)SHG, is observed. It’s applicable for future signal processing and discrimination of light polarization. So far, CDSHG in several types of chiral perovskite is reported. However, all reports are about single crystalline sample. In that case, crystal anisotropy would also be related to CDSHG.

In this paper, we investigate the CDSHG in isotropic chiral polycrystalline perovskite thin film to study the effect of chirality itself. In addition, we also propose the strategy for modification of CDSHG, by applying light-matter strong coupling which are generated when the materials are placed in optical cavity. The chiral perovskite thin film exhibits large dissymmetric factor, and it goes up to 1.6 at maximum depends on the excitation wavelength. That is largest anisotropic response of CDSHG in chiral perovskite. Furthermore, the formation of the strong coupling not only gives rise to an enhancement of SHG by about one order of magnitude, but also enhances g-values at upper polaritonic band. The fact reveals that strong coupling an effective way to manipulate not only nonlinear optics but also the effect of chirality itself.