Abstract

Excited-state absorption (OSA) induced upconversion in trivalent rare earth ions is an efficient method to obtain short visible wavelength laser emission. Tm³⁺ has previously been shown to lase at 480 nm at room temperature using 1.12 µm pumping.¹ For even shorter wavelength, using 647 run and 676 nm pumping² 455-nm lasing (¹D₂–³H₄) can be simultaneously obtained, although at 77 K, However, the terminal ³H₄ level has a long lifetime, which causes ESA of the 647 nm pump (³H₄–¹G₄), making tire 480 nm transition (¹G₄–³η₆) the dominant upconversion transition. Therefore, to obtain higher efficiency for 455-nm lasing, it is necessary to quickly depopulate the ³η₄ level.

© 1993 Optical Society of America