This section is devoted to tunable uv generation near 379 nm from a NYAB laser crystal (YAl3(BO3)4 :Nd3+). Its laser emission at 1062 nm is mixed with the pump beam near 590 nm (4G5/2-2G7/2 Nd3+ levels) inside the crystal due to the second order nonlinear optical properties: 1/590 + 1/1062 = 1/379.
The used NYAB crystal was 5 mm long and was elaborated by Castech (China). Its concentration was 2.6 10^20 ions/cm3. It was longitudinally pumped with a Laser Analytical Systems dye laser, pumped by a BM Industrie pulsed YAG:Nd laser. The cavity mirrors were highly reflective at 1062 nm. The input mirror was plane, the output mirror was 18 cm radius of curvature. The cavity length was 9 cm.
The uv output power is shown in Fig. 1:
Fig. 1
Fig. 2 Excitation spectra: (1) of Nd3+ fluorescence at1062 nm, (2) of laser emission at1062 nm, (3) of uv emission
The uv excitation spectrum extends from 585 up to 600 nm, meaning that the uv emission was tunable in the 377-383 nm range.
A theoretical model explains the role of the different physical parameters.