Ueli Koch


Last Name

Koch

First Name

Ueli

ORCID

0000-0001-8796-2146

Organisational unit

01209 - Lehre Inf.technologie u. Elektrotechnik

Search Results

Publications 1 - 10 of 104
  • Compact, ultra-broadband plasmonic grating couplers
    Item type: Journal Article
    Ayata, Masafumi; Fedoryshyn, Yuriy; Koch, Ueli; et al. (2019)
    Optics Express
  • Ultrafast Beam Steering Enabled by Photonics & Plasmonics
    Item type: Conference Paper
    Leuthold, Juerg; Bonjour, Romain; Salamin, Yannick; et al. (2018)
    OSA Technical Digest ~ Optical Fiber Communication Conference
  • The plasmonic BTO-on-SiN platform – beyond 200 GBd modulation for optical communications
    Item type: Journal Article
    Kohli, Manuel; Chelladurai, Daniel; Kulmer, Laurenz; et al. (2025)
    Light: Science & Applications
    An integrated photonics platform that offers high-speed modulators in addition to low-loss and versatile passive components is highly sought after for different applications ranging from AI to next-generation Tbit/s links in optical fiber communication. For this purpose, we introduce the plasmonic BTO-on-SiN platform for high-speed electro-optic modulators. This platform combines the advantages provided by low-loss silicon nitride (SiN) photonics with the highly nonlinear barium titanate (BTO) as the active material. Nanoscale plasmonics enables high-speed modulators operating at electro-optical bandwidths up to 110 GHz with active lengths as short as 5 µm. Here, we demonstrate three different modulators: a 256 GBd C-band Mach-Zehnder (MZ) modulator, a 224 GBd C-band IQ modulator – being both the first BTO IQ and the first IQ modulator on SiN for data communication – and finally, a 200 GBd O-band racetrack (RT) modulator. With this approach we show record data rates of 448 Gbit/s with the IQ modulator and 340 Gbit/s with the MZ modulator. Furthermore, we demonstrate the first plasmonic RT modulator with BTO and how it is ideally suited for low complexity communication in the O-band with low device loss of 2 dB. This work leverages the SiN platform and shows the potential of this technology to serve as a solution to combat the ever-increasing demand for fast modulators.
  • Digital and plasmonic artificial neural networks-Improved nonlinear signal processing at high speed and low complexity
    Item type: Journal Article
    Blatter, Tobias; Zürrer, Amane; Horst, Yannik Matthias Julius; et al. (2025)
    Science Advances
    Transmission at ever higher data rates increasingly demands more advanced digital signal processing techniques, raising both power consumption and operational costs. Here, we introduce a photonic/plasmonic artificial neural network (ANN) using plasmonic modulators to directly mitigate nonlinear signal distortions carried by an optical carrier. This first-of-its-kind plasmonic ANN achieves an ultracompact footprint and high-speed operation and markedly reduces the need for electronic processing. We compare our plasmonic ANN against a traditional digital feed-forward equalizer and a Volterra series, as well as the corresponding digital ANN. The results demonstrate that an astonishingly small ANN outperforms classical equalizers by attaining higher SNR at smaller computational effort. While the digital ANN offers an ideal implementation, executing the ANN on our first plasmonic chip already shows remarkable equalization performance with minimal components. The findings reveal a path toward ultracompact, high-speed, power-efficient, low-latency alternatives to conventional signal processing.
  • Perpendicular Grating Coupler Based on a Blazed Antiback-Reflection Structure
    Item type: Journal Article
    Watanabe, Tatsuhiko; Ayata, Masafumi; Koch, Ueli; et al. (2017)
    Journal of Lightwave Technology
  • Pockels-effect materials for plasmonic modulators
    Item type: Conference Paper
    Messner, Andreas; Haffner, Christian; Heni, Wolfgang; et al. (2018)
    OSA Technical Digest ~ Advanced Photonics 2018 (BGPP, IPR, NP, NOMA, Sensors, Networks, SPPCom, SOF)
  • PLD Epitaxial Thin‐Film BaTiO₃ on MgO − Dielectric and Electro‐Optic Properties
    Item type: Journal Article
    Winiger, Joel; Keller, Killian; Moor, David; et al. (2024)
    Advanced Materials Interfaces
    The study demonstrates high-quality pulsed-laser-deposited (PLD) barium titanate (BTO) thin-films on a magnesium oxide substrate. The frequency response of the relative permittivity (dielectric constant) and the linear electro-optical coefficient (Pockels coefficient) are measured. At 0.2 GHz, the Pockels coefficient is fitted to be r42 ≈ 1030 pm V−1. It decreases to ≈390 pm V−1 at 10 GHz after which it remains constant up to 70 GHz. The unbiased BTO permittivity is measured to be εa ≈ 7600 at 0.2 GHz, dropping to ≈1100 at 67 GHz, while the biased BTO had a permittivity εa ≈ 2000 at 0.2 GHz, dropping to ≈500 at 67 GHz. These results fill an important experimental characterization gap for high-speed BTO applications and show the high quality of PLD-grown BTO films. Lastly, the material's crystalline quality is characterized and the domain distribution is imaged. The findings enable the design and fabrication of a new generation of BTO-based components for sensing and communications.
  • Versatile Nanoscale Three-Terminal Memristive Switch Enabled by Gating
    Item type: Journal Article
    Lewerenz, Mila; Passerini, Elias; Cheng, Bojun; et al. (2024)
    ACS Nano
    A three-terminal memristor with an ultrasmall footprint of only 0.07 mu m(2) and critical dimensions of 70 nm x 10 nm x 6 nm is introduced. The device's feature is the presence of a gate contact, which enables two operation modes: either tuning the set voltage or directly inducing a resistance change. In I-V mode, we demonstrate that by changing the gate voltages between +/- 1 V one can shift the set voltage by 69%. In pulsing mode, we show that resistance change can be triggered by a gate pulse. Furthermore, we tested the device endurance under a 1 kHz operation. In an experiment with 2.6 million voltage pulses, we found two distinct resistance states. The device response to a pseudorandom bit sequence displays an open eye diagram and a success ratio of 97%. Our results suggest that this device concept is a promising candidate for a variety of applications ranging from Internet-of-Things to neuromorphic computing.
  • All-Plasmonic IQ Modulator With a 36 mu m Fiber-to-Fiber Pitch
    Item type: Journal Article
    Ayata, Masafumi; Fedoryshyn, Yuriy; Heni, Wolfgang; et al. (2019)
    Journal of Lightwave Technology
  • Atomic scale memristive photon source
    Item type: Journal Article
    Cheng, Bojun; Zellweger, Till; Malchow, Konstantin; et al. (2022)
    Light: Science & Applications
    Memristive devices are an emerging new type of devices operating at the scale of a few or even single atoms. They are currently used as storage elements and are investigated for performing in-memory and neuromorphic computing. Amongst these devices, Ag/amorphous-SiOx/Pt memristors are among the most studied systems, with the electrically induced filament growth and dynamics being thoroughly investigated both theoretically and experimentally. In this paper, we report the observation of a novel feature in these devices: The appearance of new photoluminescent centers in SiOx upon memristive switching, and photon emission correlated with the conductance changes. This observation might pave the way towards an intrinsically memristive atomic scale light source with applications in neural networks, optical interconnects, and quantum communication.
Publications 1 - 10 of 104