Exploring the Path of Optical Module Technology

In the rapidly evolving field of optical module communication, some urgent demands have surfaced due to the exponential growth of data traffic and the ever-increasing need for faster and more reliable internet services. Optical modules are crucial components in data transmission, converting electrical signals into optical signals for transmission over fiber optic cables. As the backbone of modern communication networks, they play a vital role in data centers, telecommunications, and various high-speed internet services. In this article, we will focus on the latest advancements in optical module technology that address key challenges in current networks.

Why Upgrading Optical Module Technology is Necessary?

  • Demand for Higher Bandwidth: The rapid growth of data centers has created a strong demand for optical modules with higher bandwidth, lower power consumption, and smaller sizes. Current optical modules can face bandwidth bottlenecks when transmitting large amounts of data, making it difficult to meet the increasing business demands.
  • Signal Transmission Quality: Long-distance transmissions are often plagued by signal attenuation and distortion, affecting the stability and reliability of communications. High manufacturing and maintenance costs of traditional optical modules also pose a considerable barrier, limiting their broader application.
  • Cost Concerns: Cost is also a significant pain point. The manufacturing and maintenance costs of traditional optical modules are high, limiting their wider application.

To address these issues, several advanced technologies have emerged.

Silicon Photonics Technology

Silicon photonics technology uses silicon to integrate optical components with electronic circuits, creating compact, cost-effective, and high-performance optical devices. This technology is particularly important for High-Performance Computing (HPC), which processes vast amounts of data and performs complex computations. HPC systems rely on parallel computing and efficient algorithms to enhance performance. Silicon photonics provides faster and more efficient optical interconnects within these systems, improving data transmission speeds and reducing latency. By integrating silicon photonics, HPC systems can handle larger datasets and execute more complex calculations with greater efficiency.

Coherent Technology

Coherent technology is an advanced optical communication method that leverages the phase information of light to transmit data. Unlike traditional intensity modulation methods, coherent technology utilizes both the amplitude and phase of light for modulation, significantly enhancing data transmission rates and efficiency. This technology relies on complex signal processing algorithms and high-precision optical components to achieve superior spectral efficiency and noise resistance. Coherent technology addresses challenges of larger datasets by mitigating signal attenuation and distortion, ensuring consistent signal quality and stability.

In the realm of coherent technology, Digital Coherent Optics (DCO) and Analog Coherent Optics (ACO) represent two distinct approaches to implementing coherent optical communication. Next, we’ll help you get in touch with DCO and ACO as well as related high speed coherent modules.

  • DCO

DCO is a coherent optical communication technology where a Digital Signal Processor (DSP) is directly integrated into the optical module to enable digital processing of optical signals. FS offers OSFP 800G SR8 features a built-in Broadcom 7nm DSP chip, which provides excellent performance and flexibility. With real-time signal monitoring and adjustment via DSP, DCO systems can dynamically detect and correct changes and interferences in light waves, enhancing system stability and reliability.

Integration Approach for DCO Modules

Integration Approach for DCO Modules

DCO modules communicate digitally with host systems, reducing module size and facilitating compatibility across various networking equipment. For example, the DCO 400G DWDM module provides 400Gb/s of optical bandwidth over a single optical wavelength using coherent Dual Polarization 16QAM modulation. It is intended to be used with a host platform to support 400G transmission over optical links.

  • ACO

ACO, on the other hand, employs analog signal processing techniques for coherent modulation and demodulation. ACO modules typically communicate with host systems using analog signals. In long-distance optical communication, the high spectral efficiency of ACO allows it to transmit more data, thus meeting the requirements of long-distance communication.

Integration Approach for ACO Modules

Integration Approach for ACO Modules

  • Differences between DCO and ACO
  1. Integration Method: DCO coherent modules directly integrate the DSP chip into the optical device, enabling digital communication between the module and the host system. This integration method facilitates communication among heterogeneous switch/router vendors and reduces the size of the module. Unlike DCO, ACO modules opt for analog communication between the module and the host system. This means that in ACO, analog signals are used for communication between the module and the host system.
  2. Signal Processing: DCO utilizes DSP for coherent modulation and demodulation. This allows it to encode digital signals into light waves and enables real-time signal monitoring and adjustment, enhancing system stability and reliability. In contrast, ACO modules employ analog techniques, naturally interacting with continuous signals and aligning better with the properties of light waves.

In conclusion, DCO and ACO technologies use different integration and signal processing methods in coherent modules, making them suitable for various communication environments and applications. Based on digital signal processing, DCO emphasizes flexibility and dynamic adjustment in the digital domain. While ACO employs analog signal processing, interacting more naturally with continuous signals, making it suitable for specific scenarios requiring analog communication.


LPO (Linear drive pluggable optics) refers to optical modules that utilize linear direct drive technology, eliminating traditional DSP and CDR chips. In these optical modules, only high-linearity Driver and TIA components are retained, with integrated CTLE (Continuous Time Linear Equalization) and EQ (Equalization) functionalities. This approach achieves advantages in reducing power consumption and latency within systems. It discards the traditional DSP or CDR, achieving superior power consumption and cost control while significantly reducing latency, bringing revolutionary changes to the field of optical communications.

Traditional Solution vs LPO Solution


The Linear Receive Optics, also known as “HALO” (Half-retimed Linear Optics), architecture has been optimized. In LRO transceivers or Active Optical Cables (AOCs), a DSP is placed only on the transmission path from electrical input to optical output for signal retiming and equalization, while the receiver side is designed linearly.

This approach significantly reduces overall power consumption while maintaining interoperability and standards compliance. Overall, LRO is defined as a transitional technology between DSP and LPO optical modules.


CPO (Co-Packaged Optics) refers to the co-packaging of switch ASIC chips and silicon photonics engines on the same high-speed motherboard, thereby reducing signal attenuation, lowering system power consumption, reducing costs, and achieving high integration. For information, please check this article.



Thanks to the above technologies, optic modules achieve higher bandwidth, lower power consumption, and cost efficiency. SiP technology boosts optical module performance and lowers costs through high integration and affordability. Coherent technology ensures reliable, high-speed transmission over long distances. LPO modules reduce power consumption and costs, while LRO enhances signal stability. CPO tightly integrates optics and electronics, enhancing overall performance. Looking ahead, innovations in these technologies are poised to revolutionize HPC networking, supporting ever-increasing data needs and paving the way for future advancements in computing and communication.