Guanidine tetrafluoroborate (GFB) crystal devices.

On July 14, the official website of the Chinese Academy of Sciences announced that recently, Chinese scientists have successfully created a new type of nonlinear optical crystal - a full-band phase-matched crystal, which revealed its physical mechanism and achieved birefringent phase in the entire light transmission range. Matching provided a new idea, and guided by it, a case of nonlinear optical crystal—guanidine tetrafluoroborate (GFB) was obtained.

The crystal is currently the first UV/deep UV nonlinear optical crystal material that has achieved full-band birefringence phase matching.

Nonlinear optical crystals are the material conditions and sources for obtaining lasers of different wavelengths. It can be used to convert the laser wavelength to extend the tunable range of the laser.

According to reports, the application of guanidine tetrafluoroborate crystals can realize 1064nm laser two-, three-, four-, and five- frequency multiplication with high efficiency and large energy output , which is expected to meet the major needs of semiconductor wafer inspection and other fields.

More importantly, high-quality, super-sized guanidine tetrafluoroborate crystals can be grown by the aqueous solution method, making it expected to become a new crystal material for large scientific devices.

Laser experiments using GFB crystals.

At present, researchers have achieved 193.2-266 nm ultraviolet/deep ultraviolet laser output based on crystal devices. The crystal transmittance of the material at 193.2 nm is <0.02%, and it can still achieve frequency-doubled laser output, which verifies its full-band phase matching characteristics.

The research was completed by the team of Pan Shilie, a researcher at the Crystal Materials Research Center of the Xinjiang Institute of Physical and Chemical Technology, Chinese Academy of Sciences. The relevant results were published online in the international academic journal Nature Photonics on June 12. The title of the paper is "All-Wavelength Phase Matching for Efficient Nonlinear Optical Frequency Conversion in Guanidine Tetrafluoroborate."

According to reports, laser is considered one of the most important inventions of mankind in the 20th century. Over the past 60 years, 13 Nobel Prizes have been closely related to laser technology. Achieving application-band phase matching in crystals is generally considered to be one of the important technical challenges, determining the power and efficiency of the final laser output. At present, there are many technical solutions to choose from, among which the birefringent phase matching technology using crystal anisotropy is the most widely used effective way to compensate for phase mismatch. This scheme has high conversion efficiency, but all existing crystals have phase matching wavelength loss.

However, the latest full-band phase-matching crystal discovered by Chinese scientists can achieve phase matching for any wavelength within the transmission range of the crystal material.

Guanidine tetrafluoroborate (GFB) crystals.

According to the official website of Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Pan Shilie, male, from Henan Province, Ph. Director of the Key Laboratory of Functional Materials and Devices; the current main research direction is the research of inorganic optoelectronic functional crystal materials.

Attached paper link: https://www.nature.com/articles/s41566-023-01228-7