October 1st, 2025
Zurich, Switzerland

Polariton Technologies, leader in high-speed electro-optic (EO) devices for optical communications, announces today new experimental results achieving 448 Gbit/s transmission in the O-band using commercial plasmonic silicon ring resonator modulators.

The measurements are related to the introduction of Polariton’s 8-channel transmitter PIC, designed for 3.2T-DR8 optical engines and transceivers. With an electro-optical bandwidth exceeding 145 GHz, ultra-compact integration, and compatibility with high-volume silicon photonics manufacturing, the PIC provides sufficient performance for 400G and 800G per lane operation, showing a way forward for a few technology generations.

As the industry targets ramp-up of next generation transceivers as early as 2027, plasmonic modulators deliver the necessary performance today. Together with energy efficiency and thermal robustness, Polariton is positioning plasmonics as the enabling technology for future data center components, AI, and HPC interconnects.

The work performed in collaboration with the ETH Zurich and the IEF (Institute for Electromagnetic Fields) marks a milestone for optical communication and is unveiled at the European Conference for Optical Communication in Copenhagen (ECOC 2025), as it highlights the pushing the boundaries of connectivity in data centers.

Plasmonic ring resonator modulators (RRMs) fabricated on silicon photonics employed at 1310 nm with PAM4 or higher-order signaling, establish best-in-class metrics for compact transceivers like CPO. While the results showcase data rates for PAM4 modulation, it also confirms the viability of PAM6 and PAM8 signaling for higher throughput. Reaching a steady improvement of what is possible in laboratory setups, the measurement instruments are the limiting factors in terms bandwidth.

“Reaching 448G per lane in the O-band with our plasmonic silicon modulators is an important first milestone. The next step is to co-optimize this device with high-speed electronics in an optical transmit engine to unlock their full performance and power consumption below the 1 pJ/bit” says Benedikt Baeuerle, co-CTO of Polariton. “The combination of silicon photonics and plasmonics will be key for next generation optical transceivers like CPOs where bandwidth, density, and power efficiency converge.”

The employed EO modulators excel for their footprint and the versatility to be integrated into a multitude of silicon photonics processes, as a back-end addition to standard semiconductor processing. Unlike silicon microrings, these components have been proven to work stable for long periods without the need of retuning after small temperature changes.

About Polariton

Polariton is a Swiss designer and manufacturer of high-performance photonic integrated circuits (PICs) for ultra-high-bandwidth and low-power applications in communication, computing, test & measurement, space, and quantum technologies. Exceptional performance is achieved by combining the established silicon photonics platform with plasmonic active devices, enabling operation in sub-THz and THz regimes with Mach-Zehnder and ring resonator modulators.

Follow us on LinkedIn @polariton-technologies

Media Contact
Helena Echeverri​​​​
info@polariton.ch
+41 44 589 51 29

Welcome to the Polariton Knowledge Center, your go-to hub for the latest in plasmonics, photonic integrated circuits (PICs), and ultra-fast electro-optic modulation.

Whereas you’re diving into the fundamentals or exploring advanced applications, this centralized directory informs you about related papers and information about the plasmonic and photonics information from Polariton.

Specifically, you will find here a curated repository of technical knowledge, designed to support engineers, researchers, product developers, and students working with high-speed optical communication systems.

Regardless if terahertz (THz) bandwidth modulators to cryogenic photonics for quantum computing. Moreover, it showcases innovations shaping the future of photonic technologies in our own Polariton style.

Nonetheless, we believe that access to well-structured, credible knowledge accelerates innovation, this is why you will find:

— Peer-reviewed publications showcasing research in plasmonic PICs
— Tutorials
— Frequently asked questions (FAQ)
— In-depth articles exploring use cases from quantum communication to data centers

Applications Covered

In essence, this content is tailored to multiple application areas, including:

— High-speed fiber-optic communication
— Sub-terahertz wireless transmission
— Photonic links in cryogenic environments
— Integration of plasmonics with silicon photonics
— Quantum photonics and on-chip signal processing
— Featured Topics and Publications

Lastly, we believe in collaboration across industry and academia. That’s why we refer to seminal works from ETH Zurich, Optica, IEEE, ACS Photonics, and more. You’ll find papers co-authored by leaders in the field, such as Prof. Juerg Leuthold, Claudia Hoessbacher, and Wolfgang Heni.

Polariton Technologies leads the way in high-speed, energy-efficient plasmonic modulators and photonic integrated circuit (PIC) components. Our cutting-edge Plasmonic Design Kit (Polariton PDK) enables groundbreaking advancements in optical communication, offering unmatched bandwidth, ultra-low power consumption, and compact designs.

Plasmonic Building Blocks are at the core of our PDK, providing the essential elements for high-speed, low-power optical signal processing. These components, including phase shifters, ring resonators, antennas, and couplers, leverage plasmonic technology to achieve compact designs with superior efficiency. By integrating Plasmonic Building Blocks, designers can create innovative photonic circuits with unprecedented performance in bandwidth and energy consumption.

Phase shifter: provides high-speed phase modulation of light.

• 3-dB EO bandwidth >500 GHz
• Plasmonic slot length range 5 to 25 µm
• Plasmonic slot width typ 100 nm
• Plasmonic losses ~0.36 dB/µm. For a length of 10 µm, one achieves <4 dB insertion loss including photonic to plasmonic converters
• Choice of slot materials
• V_π is a consequence of slot geometry and other parameters

W. Heni, et al, Plasmonic IQ modulators with attojoule per bit electrical energy consumption (Nature Communications, 2019)

Ring resonator modulator: modulates the optical path length of the ring to shift the resonance peak.

• 3-dB EO bandwidth >170 GHz
• Insertion loss <1.5 dB (in coupler), <6.5 dB (fiber to fiber)
• Drive voltage ~0.6 Vp for 408 Gbps transmission
• Proven temperature stability (published papers)

M. Eppenberger, et al, Resonant plasmonic micro-racetrack modulators with high bandwidth and high temperature tolerance (ECOC, 2021)

Antenna: directly converts RF to optical signals.

• ​Direct free-space to optical conversion

• Multiple designs possible for operation from GHz to THz

C. Benea-Chelmus, et al, Electro-optic interface for ultrasensitive intracavity electric field measurements at microwave and terahertz frequencies (Optica, 2020)

Mach-Zehnder modulator: separates light into two optical paths; the light traveling in these pathways has its phase modulated before recombination.

• 3-dB EO bandwidth >500 GHz
• Plasmonic slot length range 5 to 25 µm
• Plasmonic slot width typ 100 nm
• No travelling-wave electrodes
• Waveguide losses 3 to 5 dB/cm

Example: in a typical plasmonic chip the waveguides are 1 to 2 mm which leads to <1dB losses

B. Baeuerle, et al. 120 GBd plasmonic Mach-Zehnder modulator with a novel differential electrode design operated at a peak-to-peak drive voltage of 178 mV (Optics Express, 2019)

Thermo-optic phase shifter (heater): changes the phase by injecting a current through a resistive materiel above the waveguide.

• Serves to set the operating point to achieve optimal extinction ratio
• On-off ratio (ER) >30 dB
• On-off power ~10 mW

M.Burla, et al. 500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics (APL, 2019)

Grating coupler: couples light from a fiber into the PIC from the top side, and vice-versa.

• Insertion loss <2.5 dB​
• Optimized for C-band (1550 nm)
• Available for O-band (1310 nm)

Edge coupler: couples light from a fiber into the PIC from the side.

Combiner / splitter: separates / combines light to two waveguides with losses <1 dB.

Ring filter: filters certain wavelengths that are multiples of the length of the ring.

Directional coupler: couples light from one waveguide to another.

What matters most to your application: Speed, performance, miniaturization, or power efficiency? Let us know.

At Polariton, we’ve significantly designed our Process Design Kit (PDK) helping you turn ideas into high-performance Photonic Integrated Circuits (PICs) correspondingly addressing the real challenges of today’s datacom, sensing, T&M, wireless, and quantum industries.

At Polariton, we offer a reliable silicon photonics and plasmonics prototyping line that’s open to 3rd parties for collaborations and dedicated wafers. Most important, our services are designed to cater to the needs of research institutes, material manufacturers, and industrial partners who seek to take advantage of our unique capabilities and attractive turn-around cycles.

Similarly, our proven and scalable silicon photonics technology means that we can help you get your products to the market faster. Undoubtedly with plasmonics, we can also provide you more advanced electro-optical circuits, giving you a significant edge over your competition. Moreover, you’ll be able to fit more circuits on the same silicon real estate, ensuring that your products are future-proof.

Likewise, we understand that the market demands next-generation low-power photonic circuits, and we’re here to help you meet that demand. And generally, with our cutting-edge technology and expertise, you can rest assured that you’ll be ahead of the curve.

Subsequently, designers can choose from a list of building blocks offered by Polariton and connect them by optical routing using silicon photonics waveguides. Further, the building blocks are versatile and suitable for various applications.

Below, we explain how we support you.

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The Polariton way follows proven engineering methodologies and criteria including requirements engineering are captured in Jira, a state-of-the-art project management tool and available to the customer.  Simultaneously, followed by a feasibility study that looks into project, product, processes and people.

Additionally, by confirming the commercial viability, we reach MS0 which is the moment for you to reach your make-vs-buy decision.

Given that, your choice for us leads into the implementation and realization of your PIC, where our skilled photonic designers will design and simulate in order to de-risk the project and reach MS1. Likewise, our prototyping line, testing facilities and packaging center will insure you can access wafers, chips, known good dies and packaged devices that perform according to the simulations and specifications.

Consequently, no matter whether you are looking for your hero device, small prototype runs or face scale in your photonics application. Surely, every success story starts with a vision, the application, the requirements and lastly, the fabrication. Since Polariton’s platform of choice is silicon photonics, we can build on dozens of scaling partners in Europe and worldwide. In conclusion, volumes will be there because you plan for it, together with our trusted foundries.

Markets

• Datacom
• Wireless
• T&M
• Sensing
• Quantum

Trends

• Increasing complexity
• Speed
• Power budgeting
• Miniaturization

Photonic Integration

• Design & Simulation
• New/better building blocks
• Tools & Photonic Services

Fabrication Partners

September 22, 2024
Zurich, Switzerland

Polariton Technologies announces having achieved experimental IM/DD data rate in excess of 400 GBit/s per lane using commercial off-the-shelf ring resonator modulators in a collaboration with its research partner ETH Zurich and material supplier Lightwave Logic Inc. These are to be used in products such as 1.6T and 3.2T transceivers. This significant milestone sets a paradigm shift for the optical communication industry and paves the way for next-generation connectivity.

“ETH Zurich already demonstrated 400G per lane at OFC this year employing Mach-Zehnder modulators (MZM). This novel achievement is performed using ring resonator modulators (RRM), which are the better fit for the application because of considerably lower losses. The device loss is in the range of best-in-class modulators at 1.2 dB. Polariton is well-positioned for the 1.6T and 3.2T transceiver market with the 400G per lane products” explained Claudia Hoessbacher, CEO of Polariton.

The measurements were performed earlier in 2024 using devices optimized for 1550 nm operation. They demonstrate top performance with extinction ratio of 11.2 dB and a flat electro-optic response up to 110 GHz. “The reason we stopped measuring at 110 GHz is because we did not have calibrated instruments above 110 GHz at that time. In the meantime, we started characterizing the devices at 145 GHz and we developed devices optimized for 1310 nm wavelength operation”, commented Benedikt Bauerle, co-CTO of Polariton.

In an industry that has been forced to go parallel because of technological limitations, Polariton provides immediate relief for the next-generation products. Parallel lines fall short with reliability problems, are costly and consume more power than compact approaches that support higher transmission per lane.

Starting in October 2024, Polariton will offer early access to customers with sample quantities of 1310 and 1550 devices. This week, the company is also highlighting the advancement of its commercial devices at the European Conference for Optical Communication (ECOC) in Frankfurt.

About Polariton

Polariton is a Swiss designer and manufacturer of high-performance photonic integrated circuits (PICs) for ultra-high-bandwidth and low-power applications in communication, computing, test & measurement, space and quantum technologies markets. Exceptional performance is achieved by combining the established silicon photonics platform with plasmonic active devices enabling operation in sub-THz regimes, in particular with
Mach-Zehnder and ring resonator modulators.

Follow us on LinkedIn @polariton-technologies

Media Contact
Helena Echeverri​​​​
info@polariton.ch
+41 44 589 51 29

Juerg Leuthold ((JL) is the head of the department of Information Science and Electrical Engineering (D-​ITET) and he is the head of the Institute of Electromagnetic Fields (IEF) of ETH Zurich, Switzerland. His interest are in the field of Photonics, Plasmonics and Microwave with an emphasis on applications in communications and sensing. at Polariton (POL) he is our scientific advisor

Jürg, as Head of the Institute of Electromagnetic Fields (IEF), at ETH Zurich, you are the spiritual father of Polariton. Thank you for your time.

Polariton: What is the mission of your institute?
Prof. Leuthold: At IEF, we aim to develop the smallest, fastest, and most energy-efficient devices for optical communications and applications in the THz regime. In practice, that means inventing and developing novel concepts, chip-level design, chip fabrication, characterization, and system-level performance testing. Offering this environment that includes the whole cycle from invention up to system levels to our students is challenging and rewarding at the same time. Yet, in the end, I am convinced that we are excelling in time-to-publication, and our students get the bigger picture of what a development cycle means.

POL: When did you first get in touch with plasmonics?
JL: I started with this topic as a Professor at the KIT (Karlsruhe Institute of Technology). In 2009 Professor Fujii was a visiting scientist from Japan when I got interested in this subject. He was a theoretician and looking for new topics. So I asked him to investigate the dispersion relations of plasmons. Plasmonic research at that time had a bad reputation. It kind of was a “forbidden” subject due to the high losses of metallic waveguides. We ended up with a theoretical paper with Masafumi Fujii as the first author. I found the outcome sufficiently interesting. My own back-of-the-envelope calculations told me that super-fast modulation should be doable. At that time, we got a student, Argishti Melikyan, interested in working on a Master’s thesis with us. The common wisdom was not to work on this subject. And indeed, I found that my PhD did not supervise him well. So I decided to support Argishti myself. By 2010 we had the first concept paper presented at CLEO (Conference on Lasers and Electro-Optics). We published an absorption modulator employing ITO (Indium Tin Oxide). Said work was popularized later under the name “epsilon-near-zero” research. In 2011 we had the first proof-of-concept experiment. However, it was slow, and the modulation was weak. The deposition of ITO turned out to be difficult. We were also researching silicon-organic hybrid (SOH) modulators at this time. A research that started in 2008 with Jan-Michael Brosi. We then combined the plasmonic with the SOH technology. This took a lot of time, but in 2014 we made it to Nature Photonics. It was then the first Plasmonic modulator paper. The numbers were poor, but the concept was already there.

POL: Who funded that research?
JL: The German funding agencies were not particularly lenient at the time. So we went for an EU grant which got magically accepted. When I visited Brussels for the grant negotiation, I was welcomed with a cold dismissal, “This proposal should never have been accepted.” Well, let me say that the wish to prove that expert wrong was much of a motivation for the entire team.

POL: And what made you think that starting a company about plasmonics would be a good idea?
JL: We brought down the plasmonic losses from 40 dB to the twenties, and knowing that the fundamental losses would be smaller than 5 dB convinced us that it would have a market potential. Like for many technology projects, such loss reduction becomes a matter of engineering and stamina. Miniaturization and material research merged with visionary people. Then, the three musketeers (the Polariton Founders) took over.

POL: That’s an interesting subject. How did that work out?
JL: The “later” Founders were Master’s students when I was at KIT. I am still surprised that they followed me to Zurich. Wolfgang (Heni) was the device wizard, Claudia (Hössbacher) focused on characterization, and Benedikt (Bäuerle) developed the system-level aspects. They adopted the challenge and worked as a team, and it’s when we developed the company’s idea.

POL: Did the Founders have to be convinced to come to Switzerland?
JL: No! I told them about Toggenburg (smiles – Jürg’s region of origin).

POL: What can you tell about the Founders that not many know?
JL: With pleasure. Claudia discovered the first atomic-scale switch in the search for a modulator. This was the first optical memristor, for which we are still looking for an application. But welcome! Also, Claudia used to tell me that plasmonic modulators would not work. Today she leads a 30 people company. It’s been nice to push her ahead. While Benedikt has developed signal processing algorithms for coherent communication that were much better than any state of the art in terms of processing speed, and still are. So we are still employing them in the institute today. Finally, Wolfgang has my admiration for helping so many people in the institute and becoming a co-author of 146 papers so far. I guess he was laying the foundation for his later role as an entrepreneur.

POL: Coming back to you, what is your current role at Polariton?
JL: I love talking to the team once per month and covering the role of Scientific Advisor.

POL: Finally, what do you do when you are not thinking of work?
JL: Biking! When I was a kid, I had to cycle uphill twice a week as the church was on top of it, and I guess this helped to develop my passion for mastering alpine crossings. In the past year, we conquered as a family the Furka, Grimsel, or the Albula. All of which are worthwhile rides. Unfortunately, I am not as energetic anymore as I was once. I think I got lazy in my time in the USA. So, I am not much of an outdoor person anymore, but I like certain activities, like my yearly ski vacation. I remember I was on the slopes when you called me last time.

POL: Yes, you still picked up your phone. Thank you for that!

Interview by Stephan Koch.

Related Papers

• A. Melikyan, T. Vallaitis, N. Lindenmann, T. Schimmel, W. Freude, and J. Leusneak thold, “A Surface Plasmon Polariton Absorption Modulator,” in Conference on Lasers and Electro-Optics 2010, San Jose, California, May pages 2010 2010: Optical Society of America, in OSA Technical Digest (CD), p. JThE77, doi: 10.1364/CLEO.2010.JThE77
• A. Melikyan et al., “Surface plasmon polariton absorption modulator,” Optics Express, vol. 19, no. 9, pp. 8855-8869, Apr 2011 2011, doi: 10.1364/OE.19.008855
• J.-M. Brosi, C. Koos, L. C. Andreani, M. Waldow, J. Leuthold, and W. Freude, “High-speed low-voltage electro-optic modulator with a polymer-infiltrated silicon photonic crystal waveguide,” Optics Express, vol. 16, no. 6, pp. 4177-4191, March 2008, doi: 10.1364/OE.16.004177 A.
• Melikyan et al., “High-speed plasmonic phase modulators,” Nature Photonics, Letter vol. 8, no. 3, pp. 229-233, March 2014, doi: 10.1038/nphoton.2014.9