**Engineering
Ferroelectric Domain **

**for**** Nonlinear Photonics, Laser and
Quantum Optics**

S.N.Zhu

National
Laboratory of Solid State Microstructures & Physics Department

For the recent two decades, spurred
by the success of the semiconductor superlattice and
quasi-phase-matching (QPM) technique, engineering domain has become a hot topic
in material science and photoelectronics. The
domain-engineered ferroelectric crystal is a single crystal in which the
ferroelectric domain is modulated artificially according to some sequence,
forming so-called superlattice structure. The
physical properties associated with third-rank tensors like nonlinear
susceptibility tensor c(2) in such a crystal are modulated with domains, whereas those
associated with even-rank tensors remain constants. This makes the crystal
different from a homogeneous single domain one, and specially
favorable for applications in nonlinear photonics. In the case that the
wavelength of light wave is comparable with or smaller than the size of domain,
that is, the reciprocal vector of the modulated structure is comparable or
larger than the wave vector of light wave, many fancy physical effects may
create through the interaction of the wave vectors and the reciprocal vectors
of superlattice. For example, the enhancement of
optical frequency conversion, the amplification of light scattering signal, the generation of entangled photon pair and polariton excitation *etc*. The interests in
engineering domain structure of ferroelectric crystal lie not only in its
fundamental research but also in practical applications. Many of them have been
put to use in novel devices matched with contemporary nonlinear photonics,
laser and quantum optics.