On October 21, 2022, Anhui Crystro Crystal Materials Co., Ltd. won the bid for the procurement project of free space optical isolator of Quantum Sensing and Intelligent Sensing Technology Innovation Center of Hangzhou Institute of Very Weak Magnetic Field Major Science and Technology Infrastructure. This procurement project involves a total of 12 free space optical isolators, including two wavelengths of 795nm and ten wavelengths of 780nm.

The extremely weak magnetic field belongs to the national large scientific device. As an important part of precision measurement, it has entered the quantum era. Hangzhou Extremely Weak Magnetic Field Major Science and Technology Infrastructure Research Institute is a new high-energy research and development institution jointly built by Zhejiang Province, Hangzhou City and Binjiang District. At present, the construction mainly relies on the Institute of Large Scientific Installations of Beijing University of Aeronautics and Astronautics and the first-class discipline of "Instrument Science and Technology".

Free space optical isolator is a kind of passive optical device based on Faraday effect of magneto-optical crystal, which only allows unidirectional propagation of light in optical system. It can effectively reduce the external cavity feedback of diode laser system and cut off the reflection of free space fiber coupling. At the same time, the stability of the optical system is increased, feedback is eliminated, and damage to sensitive optical elements is avoided. Free space optical isolators can be divided into two categories: polarization dependent and polarization independent. They are widely used in various optical systems and equipment, such as lasers, optical communication systems, optical amplifiers, traveling wave cavities, etc.

Anhui Crystro Crystal Materials Co., Ltd. is a national high-tech enterprise specializing in research, development, design, processing and sales of crystal materials and application devices and a high growth seed enterprise in Hefei. The magneto-optical crystal TGG/TSAG independently developed and produced by the company has the characteristics of high extinction ratio, low absorption, low loss, etc. It can achieve reliable isolation and stable performance when applied to optical isolators.