Solid State Optics

Prof. Ulf Peschel is Professor of Solid-State Optics and Director of the Institute of Condensed Matter Theory and Optics at Friedrich Schiller University Jena. He is co-spokesperson of the Collaborative Research Centre SFB 1375 “Nonlinear Optics down to Atomic Scales (NOA)”.

His research combines theoretical modelling, numerical simulation and experiment to investigate nonlinear and quantum optical phenomena in complex photonic systems. Current activities range from synthetic temporal photonic lattices and quantum-state processing to nanophotonic light–matter interaction, exciton-polariton systems, topological photonics and strong-field nonlinear optics in low-dimensional materials and semiconductor nanostructures.

Research Areas

Prof. Peschel's research addresses fundamental and applied questions of wave propagation, nonlinear dynamics and light–matter interaction in complex photonic systems. Research interests include:

• Synthetic photonic dimensions and temporal photonic lattices
• Quantum-state generation, manipulation and interference in fibre-based photonic networks
• Nonlinear dynamics, optical thermodynamics and fluids of light
• Topological and non-Hermitian photonics
• Exciton-polaritons and strongly coupled semiconductor microcavities
• Nanophotonic light–matter interaction in photonic crystals, metasurfaces and plasmonic structures
• Nonlinear optics in two-dimensional and low-dimensional materials
• High-order harmonic generation and strong-field dynamics in solids and semiconductor nanostructures
• Electromagnetic and quantum-optical modelling from the device to the atomic scale

Teaching Fields

• Theoretical optics
• Linear and nonlinear light–matter interaction
• Nanophotonics
• Quantum and nonlinear optical dynamics
• Computational methods in photonics

Research Methods

The group combines analytical theory, large-scale numerical modelling and dedicated optical experiments. Methods include:

• Finite-difference time-domain (FDTD) simulations
• Rigorous coupled-wave analysis (RCWA)
• Beam-propagation and eigenmode methods
• Semiconductor Maxwell–Bloch modelling
• Modelling of strongly coupled exciton–photon systems
• Quantum-optical and nonlinear-dynamical simulations
• Tight-binding and Wannier-based modelling of solid-state optical response
• Numerical simulation of high-order harmonic generation
• Fibre-loop experiments for synthetic temporal photonic lattices
• Single- and two-photon correlation and interference measurements
• Numerical and experimental characterization of nanophotonic resonances and light–matter coupling

Recent Research Results

Synthetic temporal photonic lattices remain a central experimental platform of Prof. Peschel's group. By encoding synthetic spatial dimensions in the arrival times of optical pulses circulating in coupled fibre loops, complex lattice dynamics can be implemented in a reconfigurable optical system. Recent work has extended this concept into the quantum regime: time-bin-entangled photon pairs were generated, manipulated and interferometrically processed in a programmable temporal photonic lattice, enabling scalable two- and four-dimensional quantum-state operations in a fibre-based architecture [1].

Nonlinear interactions in such photonic lattices also provide access to collective phenomena usually associated with condensed-matter or quantum-gas systems. Experiments demonstrated superfluid-like propagation of light in nonlinear optical mesh lattices [2]. More recently, photon-photon interactions were used to realize thermodynamic processes at negative optical temperatures, including expansion and compression processes in an optical photon gas [3]. These concepts have subsequently been extended towards thermodynamic routing and redistribution of optical power.

A second major direction concerns strongly coupled exciton–photon systems and topological photonics. Exciton-polariton lattices provide tunable platforms for studying condensation, nonlinear dynamics and topologically protected states. Recent work demonstrated strongly tunable topological polariton modes in a structured optical cavity coupled to a two-dimensional semiconductor, providing direct control over the topological state and its coupling to propagating lattice modes [4]. New hybrid microcavity architectures further extend these systems towards polariton simulators and higher-order topological photonic states [5].

Within SFB 1375 NOA, the group investigates nonlinear light–matter interaction at nanometre and atomic length scales. Current work includes nonlinear optical processes in two-dimensional materials, high-order harmonic generation in semiconductor nanostructures and modelling of ultrafast carrier dynamics. Examples include coherent all-optical generation and read-out of valley populations in monolayer semiconductors [6] and new numerical approaches for high-order harmonic generation in quantum dots [7].

[1] Dhinwa et al., Nat. Photon. 19, 95 (2025).
[2] Wimmer et al., Phys. Rev. Lett. 127, 163901 (2021).
[3] Marques Muniz et al., Science 379, 1019 (2023).
[4] Lackner et al., Phys. Rev. Lett. 135, 166901 (2025).
[5] Düreth et al., Nano Lett. 26, 4979 (2026).
[6] Herrmann et al., Small 19, 2301126 (2023).
[7] Thümmler et al., J. Chem. Phys. 164, 094114 (2026).

Link to the Solid State Optics GroupExternal link

Link to the SFB 1375 "NOA - Nonlinear Optics down to Atomic scales"