Abstract

Diode laser pumped rare earth lasers in the 2-3-µm spectral region are discussed. This spectral region contains strong absorption bands for several important molecules. For example, water vapor and carbon dioxide have strong absorption between 1.9 and 2.1 µm, and water vapor between 2.7 and 2.9 µm. Liquid water has strong absorption bands centered at 1.9 and 2.8 µm. Lasers in these spectral regions therefore have applications in medicine and remote sensing such as coherent radar and particulate detection. Lasers in the 2-3-µm region also have uses in lightwave communications as pump sources for nonlinear materials and as eye-safe sources. The most important laser transitions in the 2-3-µm spectral region involve the trivalent rare earth ions Tm³⁺ (2 and 2.3 µm), Ho³⁺ (2 µm), and Er³⁺ (2.8 µm). Discussion centers around these ions in the crystal hosts YAG and LiYF₄ and in fluorozirconate glass and fiber. Continuous wave and Q-switched performance is discussed, as well as the issues affecting energy storage, such as upconversion and ground state depletion.

© 1989 Optical Society of America