Upcoming Events

The concept of quasi-phase-matching (QPM) was proposed in 1962, at the very beginning of the era of
lasers and nonlinear optics. However, it was not until the early 90’s, with the introduction of
periodically poled ferroelectrics by electric field poling that this concept gained practical significance.
The idea that the momentum mismatch of the interacting photons in a second-order interaction can
be compensated and, moreover, designed, has a great impact for applications in frequency conversion
of coherent light. Most commonly, QPM structures are implemented in bulk ferroelectric crystals by
periodically inverting the spontaneous polarization every coherence length. The efficiency of these
structures depends on the uniformity of the domain structure over the sample thickness and along the
propagation direction of the optical beam. The success of this technique critically depended on the
development of ferroelectric domain engineering to realize QPM devices in such materials as KTiOPO4
(KTP), LiNbO3 (LN) and LiTaO3. The fabrication technology for QPM structures in ferroelectric oxides
has by now matured enough to satisfy the needs of standard frequency-conversion schemes, especially
in low pulse-energy and in low-power applications. However, the QPM approach offers much more
capabilities provided that the structuring technology is capable of producing high-aspect ratio domainstructures,
especially for quantum technologies.
In this talk, I will review our work domain-structuring techniques for KTP isomorphs. I will present a
qualitative leap in periodic poling techniques that allows us to demonstrate devices and frequency
conversion schemes that were deemed unfeasible just a few years ago; and has allowed us to fabricate
bulk domain structures with feature sizes down to 200 nm. During the talk, I will discuss the material
properties that make these techniques feasible. I will also compare both the optical and ferroelectric
properties of LN and KTP. The current believe is that each material has its niche applications. Will this
assumption hold in the future?