Multiwavelength Temperature-Controlled Phase ModulatorBased on Cs₄PbBr₆/CsPbBr₃ PerovskiteCrystals

Abstract

Birefringent crystals have the ability to modulate polarized light, which has important applications in the field of optoelectronics. Waveplates are important devices in polarization optics to modulate the polarization and phase delay of light over a wide band of wavelength. However, conventional designs of half-wave plates and quarter-wave plates involve multiple birefringent crystals, and the fabrication process is complex and costly. Here, we report the discovery of a multiwavelength (532–785 nm) temperature-controlled phase modulator based on Cs₄PbBr₆/CsPbBr₃ perovskite crystals. It is the crystal lattice expansion that is causing the variation of the birefringence factor of Cs₄PbBr₆/CsPbBr₃ through observing crystal optical properties. The transmitted 633 nm light can be temperature-modulated to achieve the switching of optical polarization states between circularly polarized and linearly polarized states, revealing that the same crystal can switch between the functions of half-wave plates and quarter-wave plates. Other wavelengths of transmitted light can also change optical polarization states through temperature control. Given the versatility of halide perovskite-based crystals, Cs₄PbBr₆/CsPbBr₃ crystals offer a promising approach for producing waveplates and other optical devices at a lower cost.