Past events

Fabrication of on-chip integrated quantum optical devices based on ferroelectric materials

Christof Eigner, Paderborn University, Germany


Integration of complex optical setups is a promising way forward for current photonic quantum technologies. So far, most quantum applications were based on bulk optics and free-space setups, which impose superb requirements on the long-term stability of the experiments.

This can be overcome by integrating several components of the setup into one module. This approach provides a technology platform that facilitates easy integration into existing networks and the realisation of plug and play devices for advanced quantum experiments.

The ferroelectrica lithium niobate (LiNbO3) and potassium titanyl phosphate (KTP) as the materials of choice facilitate the exploitation of nonlinear effects such as photon-pair generations via parametric down-conversion (PDC). In combinations with a quasi-phase matched process, achieved by a periodic poling, any wavelength combination within the transparency window from the UV to the Infrared is accessible. A key technology for highly efficient, integratable devices are waveguide structures. Both materials support the fabrication of waveguides which guide both polarizations (TE and TM) and are therefore suitable for type II processes. Waveguides increase the interaction length of nonlinear processes, allow for easy integration into networks via fiber pigtailing, and can be used for passive switches and couplers. Both LiNbO3 and KTP exhibit a comparably large electro-optic effect which is used for electro optic switches and modulators. A tailored optical coating on the end facets of the waveguide increases the performance of the devices. The combination of all these properties provides a toolbox for a versatile kind of applications.

This talk will provide an overview about the recently developed technological facilities for integrated quantum optical devices in the Integrated Quantum Optics group at the University of Paderborn. We will show ideas, fabrication technologies and integrated devices with tailored linear and nonlinear optical properties.

Short bio

Christof Eigner was born in Brilon/Germany. From 2008 to 2013 he studied physics at the University of Paderborn. In January 2011 he joined the Integrated Quantum Optics group of Professor Christine Silberhorn as a student helper. Later that year he received his bachelor degree for his work on “Investigations of poling properties of surface-near titanium-indiffused LiNbO3”. After this, Christof Eigner proceeded working on his Master of Science in Physics degree, which he received in 2013. During this time he established the KTP technology in Paderborn. His thesis was titled “Periodically poled waveguides in potassium titanyl phosphate for quantum applications”. Christof started his PhD in late 2013. His current research focuses on the fabrication of periodically poled waveguides in KTP. In 2014 Christof has taken over responsibilities for the Paderborn cleanroom facilities, starting with the dielectric coating technology. Since 2015, he organises the facility and oversees the fabrication procedures for integrated optical devices as well as the development of novel technologies.