In conclusion, Yb/Pr co-doped β-NaY

In conclusion, Yb/Pr co-doped β-NaYF4 MCs with controllable size and morphology through varying doping concentration of Pr3+ were prepared for new insight of optical and structural anisotropy in individual particle. Upon excitation of 980 nm linear polarized laser beam, multiwavelength UC luminescence covering RGB bands are detected, resulting in white light-emission at single particle level, giving a chance to start white light laser oscillation in our β-NaYF4:Yb3+,Pr3+ microrod via whispering-gallery-mode. The anisotropy of RE ions doped β-NaYF4 MC is presented both in optical and structural performance. When excitation light propagates perpendicularly to the c-axis, which is the preferential growth axis of as-prepared MC, obvious periodical change of UC luminescence intensity with the excitation polarization angle varying from 0° to 360° is observed, while light propagates parallelly to the c-axis, there is no excitation polarization dependence, demonstrating clear anisotropic optical performance. The mechanism given based on crystal and local site symmetry analysis as well as electron cloud distribution of RE in hexagonal structure by DFT calculation well explains the anisotropic excitation polarization response for the first time, also providing a guidance for the luminescence polarization of RE in anisotropic structure. Besides, increasing dopant concentration is a useful and convenient way to improve excitation polarization dependence degree in effective excitation configuration. Simultaneously, different Raman spectra detected at different excitation direction display the structural anisotropy, well explaining the difference in Raman spectra among the β-NaYF4:Yb3+,Pr3+ MC powders with different doping concentration of Pr3+, indicating the necessary of investigation about single particle. Based on Raman spectra and excitation polarization, we have first established the relationship between anisotropic microstructure and anisotropic optical properties in individual particle. These important findings lead to the potential applications in microscopic multi-information transportation system by using optical and structural anisotropy from RE doped single nano/microcrystal or ordered nano/microcrystal array, such as bioimaging and microfluidics probes