Diamond is an ideal choice for optoelectronic devices in extreme environments due to its ultra-high thermal conductivity, broad-spectrum transmittance, and excellent physicochemical stability. At the same time, diamond also possesses excellent Raman properties, such as the largest Raman frequency shift (1332 cm-1) and extremely high Raman gain coefficient (~10 cm/GW) among the known crystals, which make it an ideal gain medium for expanding the laser wavelength and increasing the laser output power. However, the preparation technology of large-size and high-quality diamond crystals has been monopolized by foreign countries for a long time, which seriously restricts the development of high-performance laser light source in China.
The research team overcame the key technologies of large-size, low-stress diamond single crystal preparation and low roughness, high parallelism diamond crystal processing, and developed a diamond Raman laser crystal with excellent optical properties. Based on the diamond laser crystals, the team has successfully developed an eye-safe diamond Raman laser with <1 ns pulse width, MW peak power, and kHz high frequency reproduction. This achievement marks the team's significant progress in high-quality diamond laser crystal materials and Raman laser technology.
Large-size diamond Raman crystals independently grown by the team
By constructing a V-shaped folded cavity and a short Raman cavity structure, the team utilized the Raman-induced cavity inversion effect to realize the rapid release of laser energy, and ultimately obtained a 1.45 µm human-eye-safe-band diamond Raman laser with a pulse width of only 0.6 ns and a peak power of up to 913.3 kW, which set a new record of performance for the same kind of device in the international arena. In addition, the laser exhibits a high repetition frequency (1-10 kHz) and good beam quality (M² < 1.5), which can meet the application requirements of long-range and high-precision detection scenarios such asranging.
Diamond Raman laser experimental setup (left) and output characteristics (right)
The localization of large-size and high-quality diamond laser crystals will significantly reduce the manufacturing cost of Raman laser devices and inject a strong impetus for the development of related industries. In the future, the team will continue to optimize the diamond crystal growth process, improve the output performance of Raman laser devices, and promote the continuous progress of Raman crystal growth and laser technology in China.
