a) Chips with photonic integrated circuits (PICs) on a silicon nitride wafer. b) PIC chip coupled to a fiber array. c) Scanning electron micrographs of photonic integrated building blocks and devices.

Emerging Platforms for Integrated Photonics

Dr. Sebastian Wolfgang SCHMITT

a) Chips with photonic integrated circuits (PICs) on a silicon nitride wafer. b) PIC chip coupled to a fiber array. c) Scanning electron micrographs of photonic integrated building blocks and devices.

Image: Fraunhofer IOF

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 focuses on oxide- and perovskite-based photonic platform materials in which optical functionality is governed by material phase engineering and controlled defect structures. Key systems include non-centrosymmetric ferroelectric oxides such as BaTiO₃ and further hybrid metal and ternary oxide films and stacks fabricated by atomic layer deposition (ALD), molecular beam epitaxy (MBE) or pulsed laser deposition (PLD), including embedded two-dimensional transition metal dichalcogenides. These materials can be directly integrated on insulator platforms and used to functionalize silicon and silicon nitride photonic backbones to achieve tailored nonlinear and electro-optic responses. Implemented in nanophotonic waveguides and resonators, they enable on-chip quantum light generation, frequency conversion, and electrically tunable photonic components (current projects: Attract SILIQUA www.iof.fraunhofer.de/de/presse-medien/Aktuelles/SILIQUAExternal link, BMFTR MEXSIQUO, www.quantensysteme.info/projektatlas/projekte/q/mexsiquoExternal link).

Calculated second harmonic generation efficiency at 775 nm and polarization of barium titanate (BaTiO3) 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: Reference 1).
Image: See reference 1.

Teaching Fields

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

Research Methods

The research in the EPIQ group combines material synthesis studies (in-house and with external partners) 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 (Nanosurf NaniteExternal link), and cathodoluminescence spectroscopy (Delmic SparcExternal link), enabling correlative nanoanalytics of emerging photonic materials and platforms. For complementary structural materials analysis using X-ray diffraction or Rutherford backscattering spectrometry we rely on collaboration with external partners. 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: Reference 2).
Image: See reference 2.

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