Abstract

The potential surgical applications of 2.8-µm radiation due to its strong absorption in water and thus in biological tissue has motivated the investigation of laser operation in erbium-doped host materials. Modem surgical applications demand a compact laser system with high output power. GaInAs diode lasers at 970 nm are an excellent pump source for Er³⁺ lasers and allow the desired compactness.The best pump wavelength for an erbium 3-µm laser is 970 nm leading to a transition into the upper laser level [1]. Fluoride hosts promise high efficiency .This has been confirmed by several experiments, that have been raising the efficiency in LiYF₄:Er³⁺ up to 40 % [2] with Ti:sapphire-pumping and 35 % [3] with diodepumping. The optimization of the slope efficiency for LiYF₄:Er³⁺ lasers is still assumed to proceed towards the theoretically predicted efficiency maximum of 56 % [4]. Efficient lasers are also reported in BaY2Fg: Er³⁺. For this crystal we expect a similar efficiency as in LiYF₄: Er³⁺, especially for optimized erbium concentrations of 10 to 15 at.% [5].

© 1996 IEEE