On the possibility of applying fluoride neodymium-activated crystals as light-controlled gates for ArF laser radiation (193 nm)

Optical properties of KY$_{3}$F$_{10}$:Nd$^{3+}$, Na$_{3}$Y$_{6}$F$_{22}$:Nd$^{3+}$, SrF$_{2}$:Nd$^{3+}$, and CaF$_{2}$:Nd$^{3+}$ fluoride crystals in the UV and VUV spectral regions are presented. Absorption spectra from the ground $(^{4}I_{9/2})$ and excited ($^{4}F_{3/2}$) states are recorded in the wavelength range from 190 to 240 nm. The absorption spectra from the excited state demonstrate a significant increase in the absorption coefficients of the investigated samples near 193 nm under IR pumping of the $^{4}F_{3/2}$ state of Nd$^{3+}$ ions. The results obtained show the possibility of applying these crystals as optical gates for the UV and VUV regions, which are controlled by external laser IR radiation (e.g., for excimer ArF laser radiation with a wavelength of 193 nm, which has started to be applied in photolithography).