Abstract

Several advantages of diode-pumped solid-state Yb:YAG lasers relative to diode-pumped Nd:YAG lasers include a four-fold reduction in thermal load and four-fold increases in both the fluorescence lifetime and absorption bandwidth.¹ The thermal load arises principally from the quantum defect (i.e. the energy difference between the pump and laser photons) which, for the trivalent ytterbium ion Yb³⁺, is the lowest of any known 1-μm wavelength ion, given its InGaAs-diode-pumpable absorption features at 941 nm and 968 nm and its lasing transition at 1.03 μm. Furthermore, its simple two-electronic-manifold structure eliminates deleterious processes such as excited state absorption and upconversion from degrading its laser performance. To date, end-diode-pumped Yb:YAG lasers have been reported in various geometries^2,3 with slope efficiencies as high as 80% with respect to absorbed power.⁴ More recently, we reported the first side diode-pumped Yb:YAG laser which achieved an output energy of 50 mJ/pulse.⁵

© 1995 IEEE