Current Technology of Optical Modules

Recent optical module technologies focus on silicon photonics, coherent optics, linear pluggable optics, co-packaged optics, and ultra-high-speed modules for AI and data center applications. Silicon Photonics (SiPh)Silicon photonics integrates optical components on silicon substrates using CMOS manufacturing processes, offering high integration, cost efficiency, and scalability. It is particularly advantageous for short-range applications and coherent optics, enabling data center networks to upgrade to 400G and beyond while reducing costs and improving performance.

Challenges include optical losses and yield rates, but SiPh is expected to dominate as data rates increase and 800G transmission becomes more common.

Coherent Optical Technology

Coherent optics enables long-distance, high-speed transmission with superior signal-to-noise ratios. It is widely used in data center interconnects (DCI), metro, and long-haul networks. Coherent modules, such as 400G QSFP-DD ZR and ZR+, support high-capacity transmission and are increasingly adopted as single-channel rates rise.

Linear Pluggable Optics (LPO) and Half-Retimed Linear Optics (LRO)LPO simplifies module design by removing DSP and CDR chips, retaining high-linearity drivers and TIAs with continuous-time linear equalization. This reduces power consumption and latency, making it ideal for short-range server-to-switch connections.

LP

O modules can reduce power usage from over 13W to under 4W for 800G modules.

LR

O serves as a transitional technology, placing DSPs for signal retiming on the transmission path while maintaining linearity on the receiving end. It balances performance, power efficiency, and interoperability.

Co-

Packaged Optics (CPO)CPO integrates switch ASICs and optical engines on the same high-speed board, reducing signal attenuation, power consumption, and cost. While still in early development, CPO is expected to become critical as data rates approach 1. 6T, offering a future-proof solution for high-density, high-performance optical communication.

High-

Speed Form Factors and ModulationModern optical modules use OSFP and QSFP-DD form factors, supporting 800G and emerging 1. 6T/3. 2T speeds.

Technologies include: PAM4, PAM6, PAM8, and 16-QAM for higher-order modulationWavelength Division Multiplexing (WDM) scaling from 8 to 16–32 channelsSpatial Division Multiplexing using multi-core or multi-mode fibersAdvanced lasers (DFB, VCSEL) and photodetectors (Ge-on-Si PIN/APD) for optimized performance.

Applications and Market Trends

The growth of AI data centers, hyperscale cloud infrastructure, and 5G networks drives demand for high-speed, low-latency, and power-efficient optical modules. Silicon photonics and CPO are gaining traction due to their integration advantages and scalability, while 1. 6T technologies are moving toward commercialization in hyperscale environments.

The market is shifting from standalone modules to complete data center connectivity solutions, emphasizing system-level performance and reliability.

Summary

Recent optical module technologies are evolving to meet the demands of AI, HPC, and next-generation data centers. Key trends include: Silicon photonics for integration and cost efficiencyCoherent optics for long-distance, high-speed transmissionLPO and LRO for power-efficient short-range connectionsCPO for ultra-high-speed, co-located optical-electrical integrationAdvanced modulation and WDM techniques for 1. 6T and 3.

2T scalability These innovations collectively enable higher bandwidth, lower latency, and energy-efficient optical communication, supporting the rapid growth of modern data networks.