Materials Development for Mid-IR Solid-State Lasers

Solid-state lasers operating in the mid-IR wavelength region (3-5 mum) continue to be of great current interest for applications in laser remote sensing of chemical and biological agents, IR countermeasures, and bio-medical procedures. The development of mid-IR solid-state lasers based on oxide and fluoride crystals is hampered by large non-radiative decay rates through multi-phonon emission. On the contrary, rare earth (RE) doped crystals with low maximum phonon energies have shown efficient mid-IR emission as well as lasing at room temperature [1-9]. Examples of emission transitions in the 3-5 mum spectral region are indicated in Fig. 1 for the rare earth ions Pr³⁺, Nd³⁺, Dy³⁺ and Er³⁺.