Bridging Electrical and Optical Worlds: Enabling Accurate End-to-End EOE Simulation for Ethernet Systems
As data rates continue to surge across AI clusters, cloud infrastructure, and next-generation networks, the industry is rapidly shifting from electrical interconnects to optical communication. Optical links offer unmatched bandwidth, lower loss, and improved signal integrity over long distances, making them essential for modern high-speed systems.
But designing these systems isn’t straightforward.
At the heart of every optical link lies a critical transformation: Electrical → Optical → Electrical (EOE). And understanding this transformation holistically is the key to building reliable, high-performance systems.
The Challenge: Designing Across Two Worlds
In a real system, electrical and optical domains are tightly coupled:
- High-speed electrical signals from SerDes drive optical modulators
- Optical signals propagate through fiber with physical impairments
- Photodetectors convert light back into electrical signals for processing
Traditionally, engineers simulate these domains separately. But this approach breaks down when:
- Electrical impairments interact with optical effects
- Device-level nonlinearities impact system-level performance
- Noise sources propagate across domains
The result? Inaccurate predictions, late-stage surprises, and costly redesigns.
To truly understand system behavior, engineers need end-to-end co-simulation of the complete EOE link.
The Need for True End-to-End EOE Simulation
An EOE system is more than just a chain of components, it’s a multi-physics, multi-domain system involving:
- Electrical drivers and receivers
- Optical modulators and lasers
- Fiber transmission effects
- Detection and signal processing
Capturing these interactions requires:
- A unified simulation environment
- Accurate models across domains
- System-level analysis aligned with standards like Ethernet
This is exactly where Keysight’s solution comes in.
Introducing a Unified EOE Solution
By combining Keysight Photonic Designer with System Designer for Ethernet within ADS, engineers can now simulate the complete EOE chain in a single environment.
This unified workflow enables:
- Seamless integration of electrical and photonic components
- Standard-compliant Ethernet system simulation
- True co-simulation across domains
- Faster design iterations with higher confidence
Instead of stitching together multiple tools, engineers can now model:
- Transmitters (IBIS/AMI-based electrical models)
- Optical modulators (MZM, MRM, EAM, DML)
- Optical fiber (Single and Multimode) and WDM systems
- Photodetectors (PIN, APD) and TIAs
- Receiver DSP and BER analysis
all within one cohesive framework.
Why This Matters: Capturing Real-World Effects
One of the biggest advantages of end-to-end EOE simulation is the ability to capture real-world impairments that are often missed in isolated simulations.
1. Modulator Nonlinearity – A Hidden Performance Killer
Optical modulators, such as Mach-Zehnder Modulators (MZMs), are inherently nonlinear devices.
Our simulations demonstrate that:
- Incorrect biasing shifts the operating point
- This leads to compression of PAM4 levels
- Resulting in asymmetric eye diagrams and degraded signal quality
For example:
- Non-ideal biasing compresses lower signal levels
- Biasing near peak transmission compresses upper levels
These distortions directly impact BER, but are only visible in a full EOE simulation environment.
2. Laser RIN – Noise That Scales with Power
Relative Intensity Noise (RIN) from the laser doesn’t just add noise—it behaves differently across signal levels:
- Higher optical power → higher noise variance
- Lower levels remain cleaner
- Overall, this creates non-uniform noise distribution across PAM levels
In a linear system, this effect may appear manageable—but when combined with nonlinearity, it becomes significantly more complex and impactful.
3. Fiber Effects – Dispersion and ISI
As link distances increase, fiber impairments such as chromatic dispersion introduce:
- Pulse broadening
- Inter-symbol interference (ISI)
- Eye closure in both vertical and horizontal directions
Unlike nonlinearity (which compresses levels), dispersion distorts timing—making it a fundamentally different challenge that must be analyzed together with other effects.
The Power of Co-Simulation
What makes these results particularly valuable is not just the individual effects—but their interaction.
Only a true EOE simulation can answer questions like:
- How does RIN behave under nonlinear modulation?
- How do electrical impairments amplify optical distortions?
- What is the combined impact on BER and eye quality?
With Keysight ADS, engineers can:
- Visualize eye diagrams and BER contours
- Sweep parameters across domains
- Identify system bottlenecks early
- Optimize both electrical and photonic components together
Scaling to Real Systems: From Single Channel to WDM
The solution is not limited to simple links.
Engineers can extend simulations to:
- Multi-channel WDM systems
- High-speed Ethernet standards
- Complex system architectures
This enables realistic evaluation of modern data center and telecom links—before any hardware is built.
Accelerating Innovation in Optical System Design
As systems become more complex, the gap between electrical and optical design must disappear.
End-to-end EOE simulation provides:
- Higher accuracy – Capture real-world impairments
- Reduced risk – Avoid late-stage surprises
- Faster development – Iterate quickly in a unified environment
- Better performance – Optimize the entire system, not just parts
Explore the Solution
If you’re designing next-generation optical links, it’s time to move beyond fragmented workflows.
Discover how you can simulate and optimize complete EOE systems with Keysight:
- https://www.keysight.com/us/en/lib/resources/miscellaneous/eda-software/photonic-design-automation-software.html
- https://www.keysight.com/us/en/assets/6126-1246/videos/Photonics-EOE.mp4
- https://www.keysight.com/us/en/assets/3126-1340/application-notes/End-to-End-Electrical-Optical-Electrical-Flow-in-Keysight-ADS.pdf
Start exploring the solution and unlock accurate, end-to-end optical system design.
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