The idea to write a new book in the field of ferroelectric crystals arose from some
considerations reported in the following. In the last 5 years, several groups all around
the world in the field of engineering and characterization of ferroelectric crystals
have published more than 300 papers. The motivation for such an intense research
activity is referable to the fact that the ferroelectric crystals are a key element for
the most attractive and useful photonic and optoelectronic devices. In fact, during
the 60ies, the scientists realized that the ferroelectric crystals could have been efficiently
used to generate new, unavailable frequencies, taking advantage of the
freshly proposed birefringent phase-matching method. The synchronized rush for
the development of novel coherent sources and for the discovery of the best-suited
nonlinear crystals for mixing and generation had started. Consequently, the range of
applications of ferroelectric crystals has enormously widened in the last years, especially
based on the use of periodically poled structures (i.e., PPLN, PPLT, PPKTP,
or PPKTA) to quasi-phase-match optical interactions. A new generation of sources
is finding increasing applications in various fields, including high sensitivity trace
gas monitoring and any kind of advanced spectroscopic set-ups, thus replacing “old
style” gas lasers like Argon-ion or dye lasers. New possibilities are also being explored
to engineer ferroelectric crystals with two- or three-dimensional geometries.
Results from this field will allow developing photonic devices combining photonic
band-gap properties and nonlinear conversion processes, i.e., nonlinear photonic
crystals