Deterministic relation between optical polarization and lattice symmetry revealed in ion-doped single microcrystals

TL;DR

This study establishes a direct, quantitative link between the lattice symmetry of ion-doped microcrystals and the polarization of emitted light, enabling precise polarization control and micro-sensing applications.

Contribution

It provides the first experimental evidence of a deterministic relation between lattice symmetry and optical polarization in doped crystals, with a novel optical method for 3D orientation identification.

Findings

Lattice constant ratio c/a quantifies the polarization degree.

Polarization is directly related to lattice symmetry.

Proposed optical technique for microcrystal orientation detection.

Abstract

Rare-earth ions doped crystals are of great significance for micro-sensing and quantum information, whilst the ions in the crystals emit light with spontaneous partial polarization, which is, though believed to be originated from the crystal lattice structure, still lacking a deterministic explanation that can be tested with quantitative accuracy. We report the experimental evidence showing the profound physical relation between the polarization degree of light emitted by the doped ion and the lattice symmetry, by demonstrating, with unprecedented precision, that the lattice constant ratio c/a directly quantifies the macroscopic effective polar angle of the electric and magnetic dipoles, which essentially determines the linear polarization degree of the emission. Based on this discovery, we further propose a pure optical technology to identify the three-dimensional orientation of a rod-shaped single microcrystal using the polarization-resolved micro-spectroscopy. Our results, revealing the physical origin of light polarization in ion-doped crystals, open the way towards on-demand polarization control with crystallography, and provide a versatile platform for polarization-based microscale sensing in dynamical systems.