Conclusion
Nonlinear Crystals and Nonlinear Optics

The crystalline growth of birefringent single crystals with uniaxial or alternating periodic domains has given a major boost to non-linear laser optics, firstly for the manufacture of polarizers and quarter-wave plates, then for electro-optical Pockels cells and Faraday magneto-optical crystals for nanosecond pulse lasers, as well as for frequency tuning in a wide spectral range of optics between the ultraviolet and near infrared. These crystals are making a major contribution to the development of compact, robust "all-solid-state" laser sources, consisting of a laser diode (semiconductor), an inorganic laser crystal doped with rare-earth or transition metal ions, and a nonlinear crystal. At present, the far infrared and far ultraviolet fields are being explored the most, due to the many applications expected.