We report on a millijoule-level fiber–solid hybrid hundred-picosecond laser system with a stable performance and compact structure. The laser system is based on a master oscillator power amplifier structure containing an all-fiber master oscillator, a quasi-continuous-wave side-pumped Nd:YAG regenerative amplifier, and a double-pass amplifier. By using the filtering effect of fiber Bragg grating and the dispersion characteristics of single-mode fiber stretcher, the spectrum broadening caused by self-phase modulation effect is effectively suppressed. Thus, the gain linewidth of the Yb-doped fiber seed source and Nd:YAG laser amplifiers is accurately matched. The reason for thermally induced depolarization in the solid-state laser amplifier is theoretically analyzed, and a more flexible depolarization compensation structure is adopted in amplifier experiment. Furthermore, the pulse energy of 14.58 mJ and pulse width of 228 ps is achieved at 500 Hz repetition rate. The central wavelength is 1064.1 nm with a 3 dB bandwidth of 0.47 nm. The beam quality factors in the horizontal and vertical directions are 1.49 and 1.51, respectively. This laser system has a simple and compact structure and has a power stability of 1.9%. The high pulse energy and beam quality of this hundred-picosecond laser are confirmed by latter theoretical simulation of copper laser ablation. It is a very practical laser system for material processing and laser-induced damage.

In this paper, the laser confocal Raman spectrum of glucose standard solution was measured and studied. The relative intensity of the characteristic peak of glucose and the characteristic peak of water in the solution was used as the ratio of the measured content to measure the concentration of glucose solution.Put the prepared glucose solutions of different concentrations in a cuvette, place them on a glass slide, and place them under the field of view of the objective lens of the laser microscope Raman spectrometer stage, adjust the focal length through the eyepiece, focus the laser on the surface of the solution, and then measure Raman spectra of different solutions.The experimental results show that the relative intensity of the 1125cm-1 peak has the same trend as the actual value of glucose concentration, and there is a good linear relationship between them. This linear correlation reaches more than 0.93, and the measured LOD value is 160mg/dL This result confirms that the glucose concentration detected by Raman spectroscopy using this analytical method can be close to the normal value of human blood sugar. This will help to explore the relationship between the ratio of blood glucose peak to hemoglobin peak intensity and blood glucose content, and lay a good foundation for noninvasive blood glucose research.

Dielectric Barrier Discharge (DBD) can generate uniform and high-energy density low-temperature plasma jet at atmospheric pressure, which is often called Atmospheric Pressure Plasma Jet (APPJ). APPJ has a variety of reactive oxygen species and nitrogen products and has important application prospects in surface treatment, biomedicine, food processing, and agriculture. In this paper, the gas temperature, electron excitation temperature, and electron density of helium atmospheric pressure plasma jet (He-APPJ) were diagnosed by Optical Emission Spectroscopy (OES). The experimental results show that the activated particles emitted by He-APPJ plasma contain OH, 𝑁𝑁2 +, Helium, Oxygen, and H at 5500V~6750V. At this high pressure, most gas temperatures remain below 400K, which can be deduced that the He plasma jet is a low-temperature plasma. The electron excitation temperature is around 2000K and the electron density reaches 1014cm-3. The higher the voltage, the higher the electron excitation temperature and electron density.