Tower Semiconductor and Coherent Demonstrate 400Gbps/lane Data Transmission with a Silicon Modulator in a Production-Ready Sipho Process

Tower Semiconductor (NASDAQ/TASE: TSEM) and Coherent (NYSE: COHR) demonstrated 400 Gbps/lane data transmission using a silicon Mach-Zehnder modulator built in a production-ready silicon photonics (SiPho) process on March 23, 2026.

Rhea-AI Summary

Tower Semiconductor (NASDAQ/TASE: TSEM) and Coherent (NYSE: COHR) demonstrated 400 Gbps/lane data transmission using a silicon Mach-Zehnder modulator built in a production-ready silicon photonics (SiPho) process on March 23, 2026.

The demo achieved a clear open eye at 420 Gb/s PAM4, used Coherent’s InP CW high-power laser, and targets next-generation 3.2T optical transceivers for pluggable and co-packaged optics in datacenter links.

Positive

• 400 Gbps/lane data transmission demonstrated
• 420 Gb/s PAM4 showed a clear open eye
• Production-ready SiPho process used for the silicon modulator

Negative

• Demo relied on Coherent’s InP CW high-power laser, not an all-silicon light source
• No commercial shipment timeline or binding customer agreements disclosed

Argus Mar 23 session

+5.19% close to close Open Argus

Details

News Market Reaction – TSEM

In the Mar 23 session, TSEM gained 5.19%, reflecting a notable positive market reaction.

Data tracked by StockTitan Argus on the day of publication.

Market Context

The stock moved +5.2% in the session following this news. A strong positive reaction aligns with Tow...

Analysis

The stock moved +5.2% in the session following this news. A strong positive reaction aligns with Tower’s broader push into AI-focused silicon photonics, highlighted by the 400 Gbps/lane SiPho modulator and prior OFC‑linked collaborations. Historically, however, several upbeat AI and photonics releases saw mixed follow‑through, with 4 of the last 5 news events followed by negative moves. Investors would need to watch whether enthusiasm fades as earlier gains do, or whether continued design wins and capacity investments sustain momentum.

Key Figures

Data rate per lane: 400 Gbps/lane Target transceiver bandwidth: 3.2T PAM4 data rate: 420 Gb/s

Data rate per lane

400 Gbps/lane

Silicon modulator demonstration in production-ready SiPho process

Target transceiver bandwidth

3.2T

Next-generation optical transceivers targeted by this demonstration

PAM4 data rate

420 Gb/s

Clear open eye at 420 Gb/s PAM4 in the demo

Historical Context

5 past events · Latest: Mar 17

5 events

1. Mar 17

   AI power platform

   24h Move

   -0.4%

   Gen3 BCD LDMOS platform to address AI data-center power demands.

2. Mar 16

   AI networking deal

   24h Move

   +11.1%

   Collaboration with Oriole on nanosecond optical circuit switching for AI.

3. Mar 04

   OFC 2026 showcase

   24h Move

   -1.6%

   Plan to highlight SiPho roadmap and AI-oriented photonics solutions at OFC.

4. Feb 25

   Salience Labs partnership

   24h Move

   -0.0%

   Pre-production move for PIC-based optical circuit switches for AI data centers.

5. Feb 19

   Quantum photonics pact

   24h Move

   -1.9%

   Expanded collaboration with Xanadu to advance photonic quantum hardware.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

silicon photonics, co-packaged optics, pam4

3 terms

silicon photonics technical

"using a silicon modulator built in a production-ready silicon photonics (SiPho) process"

Silicon photonics is the technology that uses tiny structures etched into silicon chips to generate, control and detect light for moving data and sensing, essentially putting optical fiber functions onto a computer chip. For investors, it matters because it can dramatically increase data speed and energy efficiency in data centers, telecom networks and advanced sensors, potentially lowering costs and enabling new products much like replacing many metal wires with faster, low-power optical highways.

co-packaged optics technical

"extends the capabilities of silicon for pluggable transceivers and Co-Packaged Optics (CPO)"

Co-packaged optics are optical components—lasers and fiber interfaces—physically packaged together with a network switch’s main processing chip so light-based data links sit much closer to the chip instead of traveling over long electrical traces. For investors, this matters because it can dramatically cut power use, boost data speed and density, and lower system costs in large data centers and telecom equipment, much like moving a power outlet next to a heavy appliance to avoid long, inefficient extension cords.

pam4 technical

"The demonstration showed a clear open eye at 420 Gb/s PAM4, and utilized Coherent’s InP CW"

PAM4 is a digital signaling method that sends information by using four distinct voltage or light levels instead of the usual two, letting each transmitted symbol carry two bits of data. Think of it like a radio knob with four clear positions instead of just on/off; it boosts transmission speed without needing extra wires or spectrum but is harder to read reliably, so it matters to investors because it drives demand for higher-performance chips, better cables and optics, and can affect product costs, margins and upgrade cycles in networking and data-center markets.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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The demonstration uses a silicon MZM without use of exotic materials targeting next-generation 3.2T optical transceivers

MIGDAL HAEMEK, Israel, March 23, 2026 - Tower Semiconductor (NASDAQ/TASE: TSEM), the leading foundry for high-value analog semiconductor solutions and Coherent Corp. (NYSE: COHR), a global leader in photonics, today announced a breakthrough demonstration of 400 Gbps/lane data transmission using a silicon modulator built in a production-ready silicon photonics (SiPho) process. This achievement targets next-generation 3.2T optical transceivers and extends the capabilities of silicon for pluggable transceivers and Co-Packaged Optics (CPO) in datacenter connections.

Details of the modulator were presented last week at OFC. The demonstration showed a clear open eye at 420 Gb/s PAM4, and utilized Coherent’s InP CW high power laser. The performance milestone was enabled by the strong collaboration between Coherent’s advanced design expertise and Tower Semiconductor’s industry-leading SiPho platform.

The Optical transceiver market continues to outpace prior projections and next-generation bandwidth is required to continue the exponential growth in AI infrastructure.

“We strongly value the partnership with Coherent and are very excited about this breakthrough,” said Russell Ellwanger, CEO of Tower Semiconductor. “The result can extend the use of silicon for another generation of transceivers, re-utilizing the large multi-fab capacity investments we continue to make while we proceed with our work on more advanced material systems for next-generations”.

“We are pleased to partner with Tower Semiconductor on Silicon Photonics Platforms,” said Jim Anderson, CEO of Coherent. “Together with Tower Semiconductor, we are advancing high-performance optical interconnects for AI-driven data centers.”

For additional information about Tower Semiconductor’s SiPho technology platform, visit here.

About Tower Semiconductor

Tower Semiconductor Ltd. (NASDAQ/TASE: TSEM), the leading foundry of high-value analog semiconductor solutions, provides technology, development, and process platforms for its customers in growing markets such as consumer, industrial, automotive, mobile, infrastructure, medical and aerospace and defense. Tower Semiconductor focuses on creating a positive and sustainable impact on the world through long-term partnerships and its advanced and innovative analog technology offering, comprised of a broad range of customizable process platforms such as SiPho, SiGe, BiCMOS, mixed-signal/CMOS, RF CMOS, CMOS image sensor, non-imaging sensors, displays, integrated power management (BCD and 700V), and MEMS. Tower Semiconductor also provides world-class design enablement for a quick and accurate design cycle as well as process transfer services including development, transfer, and optimization, to IDMs and fabless companies. To provide multi-fab sourcing and extended capacity for its customers, Tower Semiconductor currently owns one operating facility in Israel (200mm), two in the U.S. (200mm), and two in Japan (200mm and 300mm) which it owns through its 51% holdings in TPSCo and shares a 300mm facility in Agrate, Italy with STMicroelectronics. For more information, please visit: www.towersemi.com.

About Coherent
Coherent is the global photonics leader. We harness photons to drive innovation. Industry leaders in the datacenter, communications, and industrial markets rely on Coherent’s world-leading technology to fuel their own innovation and growth.

Founded in 1971 and operating in more than 20 countries, Coherent brings the industry’s broadest, deepest technology stack; unmatched supply chain resilience; and global scale to help its customers solve their toughest technology challenges. Visit us at coherent.com.

Safe Harbor Regarding Forward-Looking Statements
This press release includes forward-looking statements, which are subject to risks and uncertainties. Actual results may vary from those projected or implied by such forward-looking statements. A complete discussion of risks and uncertainties that may affect the accuracy of forward-looking statements included in this press release or which may otherwise affect Tower’s business is included under the heading “Risk Factors” in Tower’s most recent filings on Forms 20-F, F-3, F-4 and 6-K, as were filed with the Securities and Exchange Commission (the “SEC”) and the Israel Securities Authority. Tower does not intend to update, and expressly disclaim any obligation to update, the information contained in this release. 

Tower Semiconductor Company Contact: Orit Shahar | +972-74-7377440 | oritsha@towersemi.com
Tower Semiconductor Investor Relations Contact: Liat Avraham | +972-4-6506154 | liatavra@towersemi.com

Attachment

• Coherent_Tower_400G_PR_FINAL03232026

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Tower Semiconductor (TSEM) and Coherent announce on March 23, 2026 about 400 Gbps/lane?

They announced a successful demonstration of 400 Gbps/lane using a silicon MZM in a production-ready SiPho process. According to company, the demo produced a clear open eye at 420 Gb/s PAM4 and targets next-generation 3.2T optical transceivers for datacenter interconnects.

Does the 400 Gbps/lane demo from TSEM indicate production availability for 3.2T transceivers?

The demo used a production-ready SiPho process but did not announce product shipments. According to company, the work targets next-generation 3.2T transceivers while further commercialization steps and timelines were not disclosed.

What role did Coherent play in the March 23, 2026 silicon photonics demonstration with TSEM?

Coherent provided advanced design expertise and an InP CW high-power laser for the demonstration. According to company, Coherent’s laser and design collaboration enabled the 420 Gb/s PAM4 open-eye performance.

How does the TSEM/Coherent 400 Gbps/lane result affect silicon photonics for datacenter optics?

The result extends silicon’s capability toward pluggable transceivers and co-packaged optics for datacenter links. According to company, it supports next-generation bandwidth needs and leverages existing multi-fab capacity investments.

Was exotic material required in TSEM and Coherent’s 400 Gbps/lane silicon modulator demonstration?

No exotic materials were used in the silicon MZM demonstration; it relied on standard silicon photonics process. According to company, the achievement used a silicon MZM in a production-ready SiPho platform paired with Coherent’s InP laser.