Nonlinear Optical Crystals for Second Harmonic Generation

Abstract

Some important nonlinear optical crystal families in three spectral regions (DUV-FIR) have been discussed with reference to their anionic groups. In the M–F–IR region iodides and chalcopyrite-type compound, in the Vis-NIR region sillenites, perovskites and KTP families and in the DUV region borate compound have been investigated. Their important optical and structural factors have been presented. As moderate birefringence increases phase matching wavelength range, the birefringence measurement has been described in more detail. Recent research has focused on optimizing the structure for obtaining high-LDT crystals in the M–F–IR region and removing the layering structure to achieve large-sized crystals in the DUV region. The entry of small ions in the first case and the replacement of stronger interlayer ions such as Ba and Sr, which have a stronger bond with double layer in the second case, are the solutions presented. Combination of two polarized structure units in such a way to make constructive superposition is followed to rise SHG efficiency. The crystals with 3D network are promising for large size growth.