Tech­no­logy

Integrated optical devices and circuits in lithium niobate and KTP are the platform many of our quantum optical experiments are built on. The idea of Integrated Quantum Optics using nonlinear optical waveguide substrates is to combine active optical elements such as frequency converters, electro- and acousto-optical devices with passive elements, like directional couplers, tapers, beam splitters and junctions. While a single linear coupler or a nonlinear waveguide are sufficient for some applications, more sophisticated device designs will monolithically integrate a number of such functionalities within a single optical waveguide chip, a so called integrated optical circuit (IOC).

A successful development of such IOCs requires elaborated fabrication technologies. Thus, one of our research activities is the development and continuous optimization of  the respective technological steps for the fabrication of integrated waveguide devices fulfilling the high demands from quantum optics.

Lithium niobate waveguides allow to fully harness the material's ferroelectric, electro-optic and acousto-optic potential and therefore provide an ideal platform for low loss integrated linear and nonlinear quantum photonics.
We employ two different types of lithium niobate waveguides in our group, which are presented hereafter. Read more...

Potassium titanyl phosphate (KTP) is another interesting nonlinear optical material for integrated quantum optics. It is highly suitable for applications that require short poling periods or high optical damage resistance and provides unique dispersion characteristics. KTP Waveguides of good optical quality can be fabricated by Rb-K-ion exchange. Read more...

Nonlinear interactions between arbitrary wavelengths within the material's transparency range can be facilitated by a periodic inversion of the spontaneous polarization, also called periodic poling. An electric field assisted poling technique allows us to  produce quasi-phase matching gratings in lithium niobate and KTP waveguides for quantum state generation and conversion. Read more...

Low insertion losses, high pump rejection and customized filter bandwidths are essential requirements for a successful quantum optical experiment. We meet them with our ability to produce multilayer dielectric coatings on different optical elements, including waveguide devices. Read more...

Scientific collaborations …

Our research activities are performed within joint cooperations with various international partners.