Deep red laser emission in Ho:YLF

Laser operation of the
⁵
S
2
→
⁵
I
7
transition in 2 percent Ho:YLF at room temperature is reported. Oscillations at
\lambda = 750
nm were obtained in flashlamp and dye laser pumped experiments. Thresholds of 4 J/cm and
3 \times 10^{-4}
J/cm were observed in flashlamp and laser pumped operation, respectively. The 750-nm transition in the Ho:YLF is a four-level laser with a stimulated emission cross section of
\sigma = 9.7 \times 10^{-19}
cm
²
.