Chrysoberyl (BeAl2O4) modification - Alexandrite (Cr+3:BeAl2O4) is a particularly attractive precious gem. It is also a uniquely versatile solid-state laser material. It has the distinction of being the first solid-state laser medium capable of tunable operation at room temperature.
Alexandrite lasers are vibronic lasers; that is, phonons, as well as photons, are emitted during lasing. The wavelength tuning is accomplished by controlling the branching of energy between phonons and photons during lasing. Alexandrite lasers have been tuned across most of the spectrum between 701 and 860 nm. The central part of the tuning range is from 720 - 800 nm. Using non-linear wavelength conversion processes such as harmonic generation and raman shifting, light has been generated at wavelengths from the deep IR (20 µm) to the VUV.
      In addition to its broad absorption bands throughout the visible spectrum, alexandrite exhibits narrow R line absorption features at wavelengths near 680 nm. These properties together with its long fluorescence lifetime make it an excellent material for both flashlamp and diode pumping. Alexandrite's thermo-mechanical properties make it an excellent performer in high power laser applications.

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