The Evolution of 100G Optical Modules: PAM4, CWDM4, LR4 Overview

You can see 100g optical modules changing how networks move data fast. Today, data centers and telecom networks want faster speeds and better results. The need for these modules is growing fast, especially with 5G and the need to save power.

• Data centers are growing fast. This means more need for PAM4, CWDM4, and LR4 modules.

• Fast modules like 100Gb/s LR1 and 400Gb/s LR4 are wanted a lot. More of these modules are being shipped.

• Experts think people will want even more 100/400Gb/s modules soon.

You should know the differences between these choices. This helps you build the best network for what you need.

Key Takeaways

• Learn how PAM4, CWDM4, and LR4 modules are different so you can pick the best one for your network.

• PAM4 technology sends data faster by using four signal levels. This doubles the data rate without needing more bandwidth.

• CWDM4 modules save money and use less energy. They work well for short or medium distances in data centers.

• LR4 modules are great for sending data far, up to 10 kilometers. They are good for linking buildings and campus networks.

• Always check your fiber setup and what you will need later before picking a 100G optical module. This helps you get the best performance and value.

100G Optical Modules Evolution

Early 100G Developments

100g optical modules started when networks needed faster speeds. The first 100g modules were a big change for data centers and telecom. These modules showed up in many places. They worked for short links inside data centers. They also worked for long connections between cities. Here are some important steps in their story:

1. Engineers made 100g optical modules. This was a big step for networking.

2. People got new ways to send data short and long distances.

3. Companies made these modules easier to use and more reliable.

Many groups helped make 100g better. The table below lists some important helpers:

Company/Group Name	Contribution to 100G Development
100G Lambda MSA Group	Made common rules for optical interfaces and helped vendors work together
MultiLane	Tested new rules to make sure they worked
Various Member Companies	Worked together to update rules for 100g and 400g optical technology

Advances in Modulation: PAM4 and Coherent Optics

100g optical modules changed how they send data. PAM4 modulation is special because it uses four amplitude levels. This lets you send more bits with each symbol than older NRZ methods. PAM4 doubles the data rate for the same bandwidth. You get faster speeds and better use of bandwidth without needing more space.

Coherent optics made things even better. Coherent systems use amplitude and phase to send data. These systems need smart signal processing. They give you higher spectral efficiency. The table below shows how PAM4 and coherent optics compare:

Aspect	Coherent Modulation	PAM4 Modulation
Modulation Complexity	Uses amplitude and phase, needs complex parts	Uses amplitude only, simpler design
Spectral Efficiency	Very high, more bits per symbol	Moderate, 2 bits per symbol
Signal Processing	Needs advanced DSP	Needs less DSP, but good error correction
Applications	Long-haul, high-capacity links	Short to medium distances, data centers
Cost and Power	Higher cost and power	Lower cost and power

Standardization and Market Trends

Standards help 100g optical modules work together. Groups like the 100G Lambda MSA set rules for how modules connect and share data. This lets you use products from different companies without problems.

There are some challenges too. High costs made it hard for small companies to use 100g at first. Upgrading networks took lots of work and skill. Sometimes, supply chain problems slowed down new modules. Different countries had different rules. New technologies compete with 100g, so you must watch the market.

Now, you see more 100g optical modules in data centers and networks. Standards and new modulation methods help you get faster speeds and better results.

Main Types of 100G Optical Modules

Key Standards and Form Factors

There are many kinds of 100g optical modules in networks today. Each kind has its own shape and follows certain rules. These things matter when you pick a module for your network.

Here are the main shapes you should know:

1. CFP was the first 100G module. It is big and can handle hard optics.

2. CFP2 is smaller and uses less power. You can put more of them in one spot.

3. CFP4 is even smaller than CFP2. Data centers use it to fit more modules.

4. QSFP28 is the most used shape. It follows the IEEE 802.3bj rule and works with many connectors.

The table below shows how these shapes are different:

Form Factor	Size Reduction	Power Consumption	Key Features
CFP	N/A	N/A	Original module, large size for complex optics
CFP2	Halved	Halved	Improved design, doubled port density
CFP4	50% smaller than CFP2	N/A	Maximized density, popular in data centers

You will also see modules like QSFP28, PSM4, cwdm4, and lr4. Each one works for different distances and jobs.

Application Scenarios

You need to pick the right module for your network. Some modules are best for short links in data centers. Others are good for long trips between cities.

The table below shows some common uses:

Application Scenario	Description
100G Multi-Channel DWDM Transmission Networks	Uses 100G rates with special features for high-density transmission.
100G Distance Extension Solution	Uses optical amplification to send data up to 2500 km.

Looking at these modules helps you plan your network. You can save space, use less power, and reach the right distance. If you know the differences, you can pick the best module for your needs.

Tip: Always check module types before you buy. This helps you avoid trouble and get the best results.

PAM4 in 100G Optical Modules

PAM4 Technology Overview

You might ask how 100g optical modules send so much data fast. The answer is PAM4, which stands for Pulse Amplitude Modulation with four levels. This technology changes how data is sent. Instead of just two signal levels, PAM4 uses four. Each symbol now holds two bits of information. This lets you send twice as much data without needing more signal bandwidth. You get faster data speeds and better use of your network.

• PAM4 modulation uses four different signal levels to code data.

• Each symbol in PAM4 stands for two bits of information.

• This method doubles the data rate compared to NRZ modulation.

• PAM4 gives you twice the data transmission of NRZ signaling.

• It puts two bits in each symbol, making bandwidth use better.

• This boost in capacity does not need more signal bandwidth.

Benefits of PAM4

There are many good things about using PAM4 in your network. First, you can reach 100gbps speeds with the cables and equipment you already have. This saves money because you do not need to buy all new things. PAM4 also helps you handle more data as your needs grow.

• Cost Efficiency: PAM4 lets you get higher speeds on the gear you have, so you do not need big upgrades. This saves money and helps you deal with more data traffic.

• Extended Reach: PAM4 can work even when signals get weaker over longer distances. This means better performance in tough spots and less need for fixing signals, which saves money and makes networks easier to manage.

Note: PAM4 helps you keep up with new needs in data centers and big networks.

Limitations and Use Cases

PAM4 is strong, but it has some problems. The four signal levels are close together, so noise can cause more mistakes. You need better error correction and signal processing to keep your data safe. PAM4 works best for short or medium distances, like inside data centers or between buildings. If you need to send data very far, you might need something else.

You should use PAM4 if you want fast data and to save money, and if your network does not need to go very far. Many data centers pick PAM4 for these reasons.

100G CWDM4 Optical Transceiver

CWDM4 Technology Explained

100g cwdm4 optical transceiver modules help networks move data in new ways. CWDM4 technology uses four different wavelengths to send data on one fiber. It changes many electrical signals into separate optical signals. These signals are joined together for sending. This lets you use your fiber better. You get fast data speeds without adding more fibers. CWDM4 makes it simple to upgrade your network as data needs grow.

Advantages of CWDM4

CWDM4 modules have many good points when you build or grow your network.

• CWDM4 modules give you cheap 100G optical connections.

• They can send data up to 2 kilometers, which is enough for most data centers.

• These modules use less power and work with lots of systems.

• You get Digital Diagnostic Monitoring (DDM) and fast data rates.

• CWDM4 transceivers cost less than 100G QSFP28 PSM4 for medium and long links.

• You also spend less money than with 100G QSFP28 LR4 transceivers.

• CWDM4 uses Coarse Wavelength Division Multiplexing. This means you can send many data streams on one fiber. It helps you use your fiber as much as possible.

Tip: CWDM4 modules help you save money and power while making your network faster.

Limitations and Applications

CWDM4 modules are best for short and medium distances. They may not work for very long links. These modules are good for data centers and campus networks. You get steady data speeds but do not go past 2 kilometers. Pick CWDM4 if you want fast data and want to use your fiber well. CWDM4 modules keep costs down and make your network easy to run.

LR4 and 100G Long-Range Modules

LR4 Technology Overview

You can use lr4 modules to send data far. These modules are special because they use four wavelengths. Each wavelength moves data at 25Gbps. The module takes four electrical channels and turns them into four optical signals. It then puts these signals together into one lane for 100Gbps. At the other end, the module splits the signal back into four channels. LR4 uses NRZ modulation. This is not the same as some other long-range modules that use PAM4. This design helps you get steady performance for long links.

• LR4 modules use four wavelengths at 25Gbps each.

• They use NRZ modulation, not PAM4.

• The module puts signals together and splits them for good data transfer.

LR4 vs Other Long-Range Options

When you look at lr4 and other long-range 100g modules, you see some big differences. LR4 can go up to 10 kilometers. This is good for most data centers and campus networks. If you need to go farther, ER4 modules can reach about 40 kilometers. ZR4 modules can go up to 80 kilometers. But these longer modules cost more and use more power. LR4 gives you a good mix of distance, price, and steady work.

• LR4 goes up to 10 km, great for data center links.

• ER4 goes about 40 km but costs more.

• ZR4 goes up to 80 km and uses more power.

• LR4 is best for steady 10 km single-mode fiber links.

Typical Applications

You can find lr4 modules in many networks. They are good for linking buildings, backbone layers, and data centers. Here are some common ways people use them:

Deployment Scenario	Description
ISP Interconnects	Used to connect different ISPs and make networks stronger.
Tiered Backbone Layers	Helps build networks in layers for better growth and speed.
Metro/Campus Aggregation	Makes fast links in city areas or big campuses.
University Campus Connections	Connects switches far apart in schools for steady work.
Metro Networks for Business	Gives 40G links for service providers using dark fiber for more speed.
Data Center Uplinks	Links server groups to main switches for better data center work.

Tip: Pick lr4 modules if you want steady, long links without high cost or power use.

PAM4 vs CWDM4 vs LR4

Performance and Distance

When you look at PAM4, CWDM4, and LR4, you see they each have their own strengths. PAM4 is good for sending data fast over short and medium distances. It uses four signal levels to reach 100gbps speeds. This helps you move more data without needing extra bandwidth. CWDM4 sends data with four wavelengths and can go up to 2 kilometers. This is enough for most data centers. LR4 modules can reach up to 10 kilometers. This makes them a good pick for longer links, like between buildings or across a campus.

Signal quality is very important for these modules. If the signal gets weak, you get more mistakes and slower speeds. You want the bit error rate (BER) to stay low for smooth data. The table below shows how PAM4 does in real networks:

Technology	Bit Error Rate (BER)	Signal Integrity
PAM4	Low (better than 1E-8 pre-FEC)	Optimal performance at 200G
CWDM4	N/A	N/A
LR4	N/A	N/A

• Good signal quality keeps bit error rates low.

• Bad signal quality can cause more mistakes and slow things down.

• You need strong signal quality to get the best speeds.

If you want to connect racks inside a data center, PAM4 and CWDM4 are good choices. For longer distances, LR4 gives you steady links up to 10 kilometers.

Cost and Complexity

You might wonder how much each module costs and how hard they are to use. CWDM4 modules usually cost less than PAM4 or LR4. This makes CWDM4 a favorite for many data centers. PAM4 modules cost more, but they give you faster speeds and are ready for future upgrades. LR4 modules often cost the most because they go farther and use more advanced optics.

Here is a quick look at the cost differences:

Module Type	Cost Comparison
100G PAM4	Higher
100G CWDM4	Lower

How easy it is to set up and fix modules also matters. CWDM4 modules are simple to use. You can plug them in and take them out easily. PAM4 modules use simpler SerDes, but you have to line up the lanes just right when you fix them. This makes PAM4 a little harder to manage.

Module	Installation Complexity	Maintenance Complexity
CWDM4	Lower (plug-and-play)	Lower (easy to remove)
PAM4	Lower (simpler SerDes)	Higher (lane alignment)
LR4	N/A	N/A

Tip: If you want to save time and money, CWDM4 modules are the easiest and cheapest to use.

Choosing the Right 100G Module

You should think about a few things before you pick a 100g optical module for your network. First, check what kind of fiber you have now. If you already use single-mode fiber, LR4 or CWDM4 might be best. If you want your network to be ready for the future, PAM4 modules work with new 400G and 800G networks.

The table below lists important things to think about:

Factor	Description
Fiber Infrastructure	Check what fiber you have (MMF or SMF, MPO or LC connectors).
Cost	SR4 and CWDM4 usually cost less than LR4 or single lambda modules.
Power Consumption	CWDM4 and new PAM4 modules often use less power than LR4.
Future-Proofing	PAM4 modules work with next-generation 400G/800G networks.
Dual Rate Needs	Decide if you need 4x25G or 4x28G connections now or later.
Fiber Capacity	BiDi modules can double your fiber capacity if you have limited fiber.

Network engineers look at these things when picking a module:

• Does it work with your network?

• How much speed and distance do you need?

• What kind of fiber and wavelength does your network use?

You should pick the module that fits your network’s needs. If you want something cheap and easy to use, CWDM4 is a great choice. If you need fast data for short links and want to be ready for upgrades, PAM4 is a good pick. For long links, LR4 gives you steady data up to 10 kilometers.

Note: Always check what your network needs before you buy. Picking the right module helps you get the best speed and value from your 100g optical modules.

You learned that PAM4, CWDM4, and LR4 are good for different jobs. When you pick 100g optical modules, think about how far you need to send data, how much money you want to spend, and if the module is simple to use. Knowing about new technology helps you get faster speeds, reach longer distances, and build a better network.

• You can spend less by picking open market choices and using designs that can change.

• New things like silicon photonics and AI will change networks in the future.
  Keep learning so your network will be ready for anything new.

 

 

 

 

 

Written by Jack Elliott from AIChipLink.

 

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