This volume focuses attention on understanding the physical origin of NLO effects in crystals at the molecular level and in particular the relationship between the macroscopic NLO effect of the crystals and their microscopic structure. Additionally, on the basis of theoretical and experimental studies, structural rules are described that facilitate the search for new NLO crystals in borate series compounds. C.T. Chen is a professor at thechinese Academy of Science where he works in the Fujian Institute of Research on the Structure of Matter

This clear and self-contained review of the last four decades of research highlights in the hot field of nonlinear optical (NLO) crystals, particularly of borate-based ultraviolet and deep-ultraviolet NLO crystals, covers three major subjects: the structure-property relationship in borate crystals, the structural and optical characteristics of various promising borate crystals, and their fruitful applications in a wide range of scientific and technological fields. Edited by the discoverers and users of these optical borate crystals, this is a readily accessible reading for semiconductor, applied and solid state physicists, materials scientists, solid state chemists, manufacturers of optoelectronic devices, and those working in the optical industry.

This clear and self-contained review of the last four decades of research highlights in the hot field of nonlinear optical (NLO) crystals, particularly of borate-based ultraviolet and deep-ultraviolet NLO crystals, covers three major subjects: the structure-property relationship in borate crystals, the structural and optical characteristics of various promising borate crystals, and their fruitful applications in a wide range of scientific and technological fields. Edited by the discoverers and users of these optical borate crystals, this is a readily accessible reading for semiconductor, applied and solid state physicists, materials scientists, solid state chemists, manufacturers of optoelectronic devices, and those working in the optical industry.

This report summarizes a four year program on the development of high efficiency nonlinear optical materials. Major achievements were the development of effective top-seeded solution growth techniques for beta-barium borate (BBO) and lithium triborate (LBO). BBO crystals were also grown for the first time in the US by the direct melt growth technique, a metastable method that leads to significantly higher growth rates than the commercial solution-growth technique. High quality crystals were made available for optical property determinations and nonlinear optical device development at government and commercial laboratories. Additional accomplishments involved development of an optimum heat-treatment technology for eliminating optical scattering centers from as-grown crystals of silver gallium selenide. Cooperative programs were carried out with NRL to quantify the effects of intrinsic and extrinsic defects on residual absorption. It was discovered that silver gallium selenide and silver gallium sulfide crystals grown from silver-rich solutions are free of anomolous absorption in the 2 micron waveband which is currently the major problem limiting generation of high intensity, tunable 3-5 micron radiation by OPO methods using these materials. A new nonlinear optical material, (La, Gd)Sc3(BO3)4 has been identified for future study.

In this paper, a description of research advance on the growth of some important uv nonlinear optical crystals, such as BBO LBO and KBBF etc., which were first invented and developed by our institute during the past decade is given. The review consists of the following contents: the choice of method for the crystal growth; the technique of the crystal growth and the development; the choice of the flux; the effects of the solution structure and other growth conditions on the crystal growth; the metastable growth of BBO crystals and BBO crystal growth from the pure melt by a direct CZ method; the habit and defect of the crystal and other important problems in the crystal growth.

Borate crystals are attractive for different technological applications because of their favorable physical and chemical properties like stability and high transparency, both high thermal and non-linear optical coefficients, making them ideal active media for highly efficient solid state lasers. In this Special Issue, different aspects of multifunctional borate crystals are discussed, including ortho- and oxyorthoborates and compounds with condensed anions, as well as their nonlinear optical and laser properties and piezoelectric characteristics. For this reason, complex investigations of the phase relationships in multi-component borate melts, the study of crystal growth conditions of novel high-temperature borates, and the development of the “crystallization conditions, composition, structure, and properties” concept will provide a scientific basis for growth technologies of high performance electronic and optical devices and components with a variety of industrial, medical and many other applications. In the meantime, these relationships can help to estimate the affinity of synthetic borate materials with their natural prototypes and structural analogues.