ENGINEERING TECHNOLOGY

Chinese scientists create new optical crystals


Laser is one of the major inventions of mankind in the 20th century. In 1960, mankind invented the first laser. For more than 60 years, 13 Nobel Prizes have been closely related to laser technology. High-quality laser light source is not only the “heart” of high-tech industry, but also a must for cutting-edge scientific research. Optical crystals are the material conditions and sources for producing lasers of different wavelengths.

On July 14, the reporter learned from the Chinese Academy of Sciences that Chinese scientists successfully created a new type of nonlinear optical crystal – full-band phase-matched crystal (GFB). This crystal is the first UV/deep UV frequency doubling crystal material that has achieved full-band birefringence phase matching, which can be used in semiconductor wafer inspection, large scientific equipment and other fields.

The research was completed by the team of Pan Shilie, Crystal Materials Research Center, Xinjiang Institute of Physical and Chemical Technology, Chinese Academy of Sciences, and the relevant results have been published in the international academic journal Nature Photonics.

GFB crystal devices. Photo courtesy of Xinjiang Institute of Physics and Chemistry, Chinese Academy of Sciences

After the research paper was submitted, it was well received by the reviewers of Nature Photonics, who believed that “the GFB material itself has been excellently characterized” and that “GFB is clearly a viable alternative crystal to barium metaborate crystal (BBO) and lithium cesium hexaborate crystal (CLBO)”.

After the paper was published, the editor-in-chief of Applied Physics Review sent an email asking: “I am very impressed by the quality of this article, are you interested in contributing to our journal?” ”

“We are already ahead of Western countries in the field of nonlinear optical crystals.” Pan Shilie, the corresponding author of the paper, told China Science News.

Based on this crystal, the laser device can output UV/deep UV laser light from 193.2 nm to 266 nm. At 193.2 nm, the crystal transmittance is less than 0.02%, and the frequency doubling laser output can still be realized, which verifies its full-band phase matching characteristics, making the crystal the first UV/deep ultraviolet frequency doubling crystal material to achieve full-band birefringence phase matching.

“Full band, meaning that the laser passes through the crystal without breakage. This is like a child, with his ability, can test 90 points, but because of poor performance, always can only test 70 points, what we do now is to stimulate his potential, so that he can get 90 points every time steadily. Pan Shilie said.

The results show that the wide phase matching wavelength range makes the GFB crystal transmittance range fully applied, which can realize the efficient and large energy output of 1064nm lasers with two, three, four and five times, which is expected to meet the major needs of semiconductor wafer inspection and other fields. More importantly, GFB can grow high-quality, ultra-large crystals by aqueous solution, making it a new crystal material for large scientific devices.

Miridin Mutailip, the first author of the paper and a researcher at the Xinjiang Institute of Physics and Chemistry, Chinese Academy of Sciences, told China Science News that because GFB crystals can be grown in an aqueous solution at 40 degrees Celsius, and the cost of raw materials is relatively cheap, the crystal production cost is relatively low, and after the GFB crystal growth process is stable, it can be easier to achieve mass production.

It is worth noting that the research is a technological breakthrough based on theoretical innovation starting from the “problem”.

“Based on the research of cutting-edge progress in the field and the analysis of the current situation of birefringence phase matching of nonlinear optical crystals, the team first proposed a hypothesis about an ideal state of nonlinear optical crystals, that is, in nonlinear optical crystals based on birefringence phase matching, can the ideal state of ‘UV cut-off edge equal to the shortest matched wavelength’ be achieved?” Mizhdin said.

Guided by this question, team members revealed the physical mechanism of phase-matched crystals in the full band. After 5 years of design and synthesis, crystals up to 70 mm× 60 mm × 50 mm in room temperature aqueous solution were successfully grown.

Researchers from the Xinjiang Institute of Physics and Chemistry are conducting laser experiments. Photo courtesy of Xinjiang Institute of Physics and Chemistry, Chinese Academy of Sciences

Pan Shilie introduced that the Crystal Materials Research Center of Xinjiang Institute of Physics and Chemistry, Chinese Academy of Sciences was established in 2007, and now, the scientific research team has brought together a group of young “post-90s” researchers like Mi Riding with the original mission of “creating a new generation of ‘Chinese brand’ crystals”, of which 3 young researchers have been funded by the National Natural Science Foundation of China. In addition, the center has also attracted senior experts from Nankai University, Harbin Institute of Technology and other universities and research institutes to join the team, which has played a good demonstration role in cultivating, retaining and attracting talents in the western region.

As the director of the Xinjiang Institute of Physics and Chemistry of the Chinese Academy of Sciences, Pan Shilie said that in the next step, the Xinjiang Institute of Physics and Chemistry will continue to carry out research on the application of related crystal materials, devices and laser light sources, and strive to produce more original and leading major innovation results. (Source: Ni Sijie, China Science News)

Related paper information:https://doi.org/10.1038/s41566-023-01228-7



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