Introduction

Research on nonlinear wave mixing in the Institute of Optical and Electronic Materials is focused on slow light enhanced Four Wave Mixing (FWM), Third Harmonic Generation (THG) as well as Cross- and Self-Phase Modulation (XPM and SPM). Silicon microstructures functionalized with nonlinear polymers as well as the silicon nonlinearity itself are used in order to include these nonlinear processes in integrated photonics.

Goals

The goal of this project is to build a micro photonic source for entangled photons as well as dispersive time stretching and compression devices (Time Lens, Time Prism, Time Telescope) and amplifiers using THG based on Silicon-on-Insulator (SOI) processing technology. Strip and photonic crystal waveguides as well as slotted waveguides and slotted photonic crystal waveguides functionalized with nonlinear polymers are investigated with respect to their FWM signal amplification gain and signal gain band width. Low pump threshold FWM and THG will be achieved via high field confinement and tuning of group velocities.

As a preliminary test one and two dimensional structures where investigated numerically with respect to their nonlinear performance using the freely available tool MEEP. Self Phase Modulation as well as Four Wave Mixing have been tested in one and two dimensional strip waveguides. Two dimensional slow light photonic crystal waveguides have been investigated with MEEP, and a quadratic dependence on group index of the nonlinear phase shift could be verified numerically. Work on optimization of slow light photonic crystal waveguides for FWM continues. To this end two different schemes are employed. In the one case the focus is on optimizing structures with respect to phase matching in the other the focus is on adjusting dispersionless slow light structures such that phase matching can be achieved. Due to large dispersion in photonic crystals the latter is the most promising one. The previously mentioned matching of phases in FWM means the dispersion of the structure is optimized such that the difference of the four interacting waves wave vectors is canceled by the phase shift caused by SPM and XPM.

The photonic crystal waveguides investigated are hexagonal arrangement of air holes in silicon with a line defect, i.e. a row of air hole missing in a symmetry direction of the crystal. This structure is then suspended in air. The optimization is done by shifting holes adjacent to the line defect appropriately.

Wissenschaftliche Kontakte und Kooperationen

• Prof. Joseph W. Perry, PhDund Joel M. Hales, PhD, Georgia Institute of Technology
• Prof. Dr. Ernst Brinkmeyer, TUHH, Optische Kommunikationstechnik
• Prof. Dr.-Ing. habil Jörg Müller, TUHH, Mikrosystemtechnik
• Prof. Dr. Klaus Petermann und Dr. Jürgen Bruns, TU Berlin, Hochfrequenztechnik/Photonik
• Prof. Dr. Bernd Tillack und Dr. Lars Zimmermann, Leibniz-Insitut für innovative Mikroelektronik