| 摘要 |
Four-fold and higher order lasers pumped by multiphoton absorption, avalanche mechanisms, or other means of internal upconversion for continuous-wave and continuous-wave mode-locked lasers. A solid-state laser system is contained within an astigmatically compensated cavity containing first and second mirrors. The gain medium is formed of a crystal of lithium yttrium fluoride heavily doped (5%) with trivalent erbium, or another form of crystal, such as CaF2 where the dopant atoms are clustered in quartets. The crystal, in a lithium yttrium fluoride embodiment, is approximately 3 mm thick with both sides thereof being polished flat to a laser grade finish. A pumping source supplies a pumping energy having a wavelength of 1.5 (my)m to the gain medium, which wavelength is considerable longer than the output wavelength (701.5 nm) of the laser system. The gain medium may additionally be an alkali vapor formed of Cesium or Rubidium.
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