4‘‘ silicon nitride wafer with photonic integrated circuits a), scanning electron micrograph of a grating coupler - scale 1µm b), evanescent coupler - scale 2µm c), multi-mode interferometer - scale 2µm d), Huygens waveguide - scale 2µm e), coupled micro ring resonators – scale 10 µm f), integrated entangled photon source - scale 25µm g), PIC chip coupled by a fiber array h).

Emerging Platforms for Integrated Photonics

Dr. Sebastian Wolfgang SCHMITT

4‘‘ silicon nitride wafer with photonic integrated circuits a), scanning electron micrograph of a grating coupler - scale 1µm b), evanescent coupler - scale 2µm c), multi-mode interferometer - scale 2µm d), Huygens waveguide - scale 2µm e), coupled micro ring resonators – scale 10 µm f), integrated entangled photon source - scale 25µm g), PIC chip coupled by a fiber array h).

Image: Anderer

Dr. Sebastian SCHMITT

E-mail: sebastian.wolfgang.schmitt@iof.fraunhofer.de
Phone: +49 3641 807-403

Sebastian Schmitt is an experimental physicist working at the interface of integrated photonics, materials science, and nanoscale fabrication and characterization. He is group leader at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF and principal investigator at the Abbe Center of Photonics, Friedrich Schiller University Jena. His research focuses on integrated and quantum photonic material platforms and Photonic Integrated Circuits (PICs). His work combines material innovation, precise nano- and micro-structuring, and advanced optical spectroscopy to explore and exploit light-matter interaction at the nanoscale, with the aim of enabling next-generation classical and quantum photonic integrated circuits.

Research Areas

Sebastian Schmitt’s research is centered on integrated nonlinear and quantum nanophotonics, with the goal of developing novel photonic platforms and devices that provide advanced classical and quantum optical functionalities. A key focus lies in exploiting the nonlinear and anisotropic optical properties of emerging materials, including ferroelectric perovskite oxides such as BaTiO₃, semiconductors such as GaP, van der Waals materials such as NbOI₂, and hybrid material systems integrated on insulator platforms. By engineering waveguides, resonators, and nanostructures, his work targets on-chip sources of nonclassical light, such as polarization- and frequency-entangled photon pairs, as well as efficient frequency conversion and electro-optic modulation. These activities are closely linked to application-driven developments in scalable nonlinear and quantum photonic circuits and integrated photonic device metrology.

Calculated second harmonic generation efficiency and polarization of barium titanate waveguides as function of waveguide width, waveguide height and polarization of the 1550 nm fundamental mode (TE, TM). Arrows indicate bands for waveguide geometries which allow generation of photonic Bell states via spontaneous parametric down conversion (SPDC)
Image: Anderer

Teaching Fields

Integrated photonics design and fabrication
Quantum state generation and manipulation at the chip level

Research Methods

The research in the Schmitt group combines material synthesis and nanofabrication-including nano- and micro-structuring up to 12’’ and ion-beam-based techniques-with photonic integrated circuit (PIC) design and characterization. Advanced optical, scanning-probe and scanning electron microscope based methods are employed for comprehensive material and device analysis. Key techniques include linear, nonlinear, and quantum optical characterization of integrated photonic devices, multidimensional Raman and photoluminescence spectroscopy, atomic force microscopy, and cathodoluminescence spectroscopy (Delmic Sparc, www.delmic.com/en/products/cl-solutions/sparc-spectralExternal link), enabling correlative nanoanalytics of emerging photonic materials and platforms. Data-driven and machine-learning-assisted analysis is used to correlate structure, strain, composition, and optical response, providing deep insight into structure-property relationships and guiding photonic device design.

Polarization dependent second harmonic generation (SHG) microscopy maps of a barium titanate (BaTiO3) flake before and after annealing showing relative intensity encoded in brightness (0-1) and orientation of the domain polarization encoded in color (0°-180°)
Image: Anderer

Recent research results

[1] Vrckovnik et al., arxiv.org/abs/2506.21228 (2025).External link
[2] Esfandiar et al., arxiv.org/abs/2508.05874 (2025).External link
[3] Abtahi et al., arxiv.org/abs/2511.15451 (2025).External link
[4] Wu et al., Small Stuct. 5, 2300494 (2025).External link
[5] Schmitt et al., ACS Appl. Electr. Mater. 3, 4409 (2021).External link
[6] Schmitt et al., Nature Sci. Rep. 9, 9024 (2019).External link

Link to the Schmitt group at the Fraunhofer IOFExternal link