Tobias Blatter

Last Name

Blatter

First Name

Tobias

ORCID

0000-0002-2211-5955

Organisational unit

03974 - Leuthold, Juerg / Leuthold, Juerg

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Publications1 - 10 of 12

A quantum walk comb source at telecommunication wavelengths
Marzban, Bahareh; Miller, Lucius; Dikopoltsev, Alex; et al. (2026)
Nature Photonics
Optical frequency combs consist of evenly spaced single frequencies that are phase-locked to one another and are highly effective in applications such as optical spectroscopy, remote sensing and telecommunications. Integrated optical frequency combs hold great promise for a broader range of consumer technologies but face challenges in terms of stability, efficiency and controllability. Here we demonstrate a quantum walk comb in synthetic frequency space formed by externally modulating a semiconductor optical amplifier operating in the telecommunication wavelength range in a unidirectional ring cavity. Although interband active regions were generally considered to exhibit slow-gain dynamics, we show that the ultra-fast intraband component of the gain saturation is responsible for the stabilization of the comb in a broad frequency-modulated state. Compared with quantum walk combs previously demonstrated using a quantum cascade laser, our device benefits from the low thresholds associated with interband emission and demonstrates a wallplug efficiency of up to 6%. Our device produces a nearly flat broadband comb with a tunable repetition frequency reaching a bandwidth of 1.8 THz at the fundamental repetition rate of 1 GHz while remaining fully locked to the radio frequency drive. Comb operation at harmonics of the repetition rate up to 14.1 GHz is also demonstrated.
All-plasmonic sub-terahertz wireless communication link
Blatter, Tobias; Koepfli, Stefan M.; Zuerrer, Amane; et al. (2025)
Nature Communications
A promising approach to increase wireless capacity is the transition to sub-Terahertz carrier frequencies (0.1–0.3 THz). While traditional high-frequency approaches employ III-V semiconductor technologies, plasmonics is emerging as a potential solution for highest-speed components. In this paper, we introduce an all-plasmonic sub-THz wireless link, utilizing compact (<50 µm²) plasmonic components that exhibit a flat frequency response up to 300 GHz while providing full flexibility in carrier frequency selection. The plasmonic approach offers unprecedented integration potential, compatibility with diverse platforms, and scalable, cost-effective fabrication. To demonstrate its capabilities, we conduct a lab experiment transmitting 120 Gbit/s on a 285 GHz carrier across a 5 m free-space link, validating the system’s linear performance and large power dynamic range. While this first demonstration is constrained in transmission distance, it showcases the transformative potential of plasmonic technology in closing the wireless-optical data-rate bottleneck: The proposed plasmonic converters could provide the capacity expansion needed for future 5G, 6G, and beyond wireless networks, paving the way for high-speed, cost-effective, and scalable sub-THz communications.
Vertical Plasmonic Electro-Absorption Modulator Based on Transparent Conductive Oxides
Dober, Marco; Torti, Giacomo; Keller, Killian; et al. (2025)
Technical Digest Series ~ Frontiers in Optics + Laser Science 2025 (FiO, LS)
We present the first proof-of-concept of a vertical plasmonic electro-absorption modulator based on TCOs. We measure a 26 GHz device bandwidth and 64 Gbit/s data rate with less than 5 µm2 active region footprint.
High-optical-output power transmissions for Tbps GEO feeder links
Maho, Anaëlle; El Marzougui, Omar; Horst, Yannik Matthias Julius; et al. (2025)
Proceedings of SPIE ~ International Conference on Space Optics — ICSO 2024
High power generation is an enabling technology for high capacity free space optical feeder links. In this paper, we review the recent results obtained in the frame of the H2020 VERTIGO project. In particular, we achieved records of C-band 100W optical output power, data rates of 100 Gbps in direct detection (4x25 Gbps) and up to 1 Tbps single channel with coherent modulation. In addition, we prove the feasibility and the good performance of a Coherent Beam Combining technique to provide higher power. Finally, we provide some simulation models to explain and predict the performance.
Digital and plasmonic artificial neural networks-Improved nonlinear signal processing at high speed and low complexity
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.
A Ultra-Stable Broadband Novel Comb Laser with Tunable Free Spectral Range and Spectra
Marzban, Bahareh; Blatter, Tobias; Miller, Lucius; et al. (2025)
2025 European Conference on Optical Communications (ECOC)
We present a novel near-infrared quantum walk comb laser, with 14 nm bandwidth, up to 6% wall-plug efficiency, and a 1 Hz RF linewidth. This broadband comb offers in situ spectral shaping and demonstrates stable data transmission performance at 64 GBd QPSK.
Ultra-Stable Broadband Comb Laser with Tunable Free Spectral Range
Marzban, Bahareh; Blatter, Tobias; Kulmer, Laurenz; et al. (2025)
Technical Digest Series ~ Optical Fiber Communication Conference (OFC) 2025
We demonstrate a novel broadband 1.6THz comb that enables dynamic adjustment of the repetition rate up to 17GHz, achieving exceptional stability with a 1Hz RF linewidth and supporting data transmission up to 64GBaud QPSK.
O-Band Plasmonic MZM Enabling Single Carrier net 400 Gbit/s IMIDD Over 1 km Fiber
Kulmer, Laurenz; Oettinghaus, Silas; Hess, Samuel; et al. (2025)
2025 European Conference on Optical Communications (ECOC)
We demonstrate a >400 Gbit/s/pol IM/DD link in the O-band by employing a 160 GBd PAM-8 signal encoded by a plasmonic MZM at a transmission distance of 1 km. Symbol rates of up to 256 GBd are successfully demonstrated.
Transparent Carrier Phase Recovery Based on an Artificial Neural Network
Blatter, Tobias; Xu, Chenrui; Kaufmann, Serge; et al. (2025)
IEEE Photonics Technology Letters
Carrier phase recovery (CPR) is crucial in coherent optical communication, ensuring reliable data transmission. This letter proposes a novel artificial neural network (ANN)- based CPR algorithm. It achieves modulation-format transparency and robust phase recovery across a wide range of signal-to-noise ratios (SNRs) at reduced computational cost compared to a two-stage blind phase search (2S-BPS). Simulations and experiments show that the proposed algorithm outperforms 2S-BPS at low SNRs with shaped quadrature amplitude modulation and surpasses universal carrier phase estimation (U-CPE) and principal component phase estimation (PCPE) with shaped formats at high SNRs. While a 3% pilot-only CPR achieves the best performance at low SNR at lowest computational cost, it does so at the cost of reduced throughput at high SNRs.
Neural network nonlinear mitigation and coherent combining to improve the SNR of free-space optical communication systems
Kulmer, Laurenz; Blatter, Tobias; Billault, Vincent; et al. (2026)
Optics Express
Optical satellite communications offer a viable path to meet the growing needs in transmission capacity of space communication networks, as well as the saturation of conventional RF bands. Yet long propagation distances and atmospheric turbulence limit coupled power, necessitating high-power amplification. To date, high-speed transmission at such power levels has not been demonstrated in a single system. Here, we report 1 Tbit/s data rates at 100 W optical power with a signal-to-noise ratio (SNR) advantage of up to 3.9 dB over a conventional single-amplifier system. The SNR advantage of 3.0 dB is obtained by mitigating amplifier-induced nonlinearities by an artificial neural network (ANN) equalizer, thereby outperforming conventional approaches by up to 2.3 dB. An additional SNR gain has been enabled by coherent beam combining of two 50 W amplifiers. The impact of beam combining is investigated, and an advantage of up to 0.9 dB SNR is shown. A system-level investigation into the SNR penalty due to high power amplification, the influence of the polarization multiplexing, and the best-case performance of the system is given. These findings provide critical insights for future high-capacity optical satellite links. Published by Optica Publishing Group under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Publications1 - 10 of 12

Tobias Blatter

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