The research on high-performance electro-optical crystals of Xi'an Jiaotong University (XJTU) was issued on April 21 in Science, a well-known international journal publishing the latest in scientific discovery.

The research results were published in a paper entitled Ferroelectric crystals with giant electro-optic property enabling ultracompact Q-switches. (Link to the paper: https://www.science.org/doi/10.1126/science.abn7711)

XJTU is the first unit of the paper. The first authors of the paper are postdoctoral fellow Liu Xin from XJTU’s School of Electrical Engineering and associate professor Tan Peng from Harbin Institute of Technology.

The research team led by XJTU professors Xu Zhuo and Li Fei managed to remove all light-scattering domain walls and enable an ultrahigh EO coefficient r33 of 900pm?/V in PIN-PMN-PT crystals, 30 times as high as that of conventional EO crystals, through synergistic design of a ferroelectric phase, crystal orientation and poling technique. 

Using PIN-PMN-PT crystals, the research team fabricated ultracompact EO Q-switches with lower driving voltages in smaller size, but the same superior performance as that of commercial Q-switches. 

a. Comparison of electro-optic coefficient of PIN-PMN-PT single crystal with other crystals, the upper left picture is the photo of PIN-PMN-PT crystal;

b. The electro-optical Q-switch developed based on PIN-PMN-PT single crystal. For comparison, the photo and working voltage of the electro-optical switch of commercial DKDP single crystal and lithium niobate single crystal are given in the figure.

The findings of the research team make great contribution to better application of PIN-PMN-PT crystals for EO devices. Besides small-sized Q-switches with a low driving voltage, PIN-PMN-PT crystals are also believed to be used for other high-performance EO devices, including LiDAR for autonomous driving, frequency converter, optical phased array.

Electro-optic crystals are widely used for electro-optical components. Currently, the electro-optic properties of crystals are not enough to satisfy the market need as a result of a trend towards smaller, lighter and more integrated optical components with low driving voltages and power consumption.

Relaxed-lead titanate (PbTiO3) crystals are credited with superior electro-optic properties with a high electro-optic coefficients reaching as much as 200pm/V. However, the optical transparency and the stability of electro-optic property are severely undermined by domain walls which scatter and reflect light, and which are easy to move under the external electric field.