Continuous oscillation of a lithium neodymium tetraphosphate laser with 200-µW pump threshold

Room temperature CW oscillation of a lithium neodymium tetraphosphate (LiNdP
4
O
12
) (LNP) laser with thresholds in the fractional milliwatt range is reported. With a 5145-Å pump, observed threshold was 200 μW and the slope efficiency was 43 percent.