The main goal of this lecture will be to present the state of the art of inorganic optical materials that is to say solid-state laser and nonlinear crystals.
In the past decade, the renewal in the search of new optical materials covering the widest spectrum from ultraviolet to infrared has been very strong and the demand of various applications in many areas is always increasing. Today, great efforts are devoted to the development of all solid-state laser sources offering advantages of compactness, long live, reliability, low noise, safety and easier maintenance with respect of gas laser systems. Such advance is due to fruitful deep basic research both in solid-state chemistry, solid-state physics and optics Laboratories.
The approach of solid-state laser uses luminescent activator ions in inorganic dielectric hosts. The 4fn electronic configuration of rare-earth ions gives mainly sharp laser lines from ultraviolet to infrared spectral ranges and the 3dn electronic configuration allows us to make tunable laser sources within red and near infrared spectral ranges. We shall show the main spectroscopic properties of laser crystals and we shall analyse the tendencies of the search of new ones in the way of the most spectacular renewal which is the development of diode-pumped solid-state laser sources in the near infrared and visible spectral region as well as upconversion schemes which lead to visible laser operation with near infrared pumping.
Another part will be focused on nonlinear crystals for which the understanding is not so advanced as laser crystals. Only a few crystals are used in commercial products. We shall compare advantages and drawbacks for each of them which are operating either by birefringence phase matching or quasi-phase matching in c(2)-type nonlinear crystals for Second Harmonic Generation (SHG) or Optical Parametric Oscillation (OPO) operations. The new area of c(3)-type nonlinear crystals used as Raman shifters will be also presented.