Analysis of Optical Module Application Scenarios

Optical modules are essential components in the realm of data communication, facilitating the conversion between optical and electrical signals. The advent of big data, blockchain, cloud computing, the Internet of Things (IoT), artificial intelligence (AI), and 5G has triggered an exponential surge in data traffic, propelling data centers and mobile communication optical interconnection to the forefront of research in the optical communications industry.

Data Center
Data centers, the heart of the digital era, house a multitude of network switches and server clusters, forming the core of structured cabling and information network equipment. These interconnected devices serve as the data aggregation center of the information network system. To facilitate seamless data exchange between servers, switches, and their counterparts, a combination of optical modules (direct-connect copper cables, active optical cables), optical fiber patch cords, and other transmission media are employed.

As the market demand for data transmission surges, IDC data centers have emerged as catalysts for enhancing the business competitiveness of small and medium-sized enterprises (SMEs). The ever-evolving landscape of data center interconnectivity and the personalized needs of customers have given rise to a diverse array of network equipment and transmission media, including active optical cables, direct-connect copper cables, optical modules, and optical fiber patch cords. To make informed decisions when selecting these devices and accessories, users must carefully consider their specific application scenarios.

Mobile Communication Base Station
Mobile communication base stations, the backbone of cellular networks, play a pivotal role in enabling seamless connectivity for mobile devices. These essential infrastructure components rely on optical modules to facilitate efficient data transmission between their constituent parts, ensuring uninterrupted communication services. Base stations typically comprise two main units: the Radio Remote Unit (RRU) and the Base Band Unit (BBU). The RRU, positioned near the cell towers, handles the radio signal processing, while the BBU, located in a central hub, manages the core network functions. To establish a reliable connection between these units, optical modules are employed. In 4G networks, the choice of optical modules for BBU-RRU interconnection depends on the specific requirements and network configuration. Commonly used options include: 1.25G Optical Modules: These modules offer a cost-effective solution for shorter-distance links, typically within a few kilometers. 2.5G Optical Modules: Providing a balance between performance and cost, 2.5G modules are suitable for applications requiring higher data rates over moderate distances. 6G Optical Modules: For high-capacity backhaul links, 6G optical modules offer exceptional bandwidth, enabling the transmission of large amounts of data efficiently. 10G Optical Modules: In scenarios demanding the highest data rates, 10G optical modules provide the necessary bandwidth to support demanding applications and future network upgrades.

Passive Wavelength Division Multiplexing(WDM) System
Passive wavelength division multiplexing (WDM) systems are mainly used in metropolitan area networks (MANs), backbone networks, and wide area networks (WANs). Commonly used are CWDM and DWDM optical modules. CWDM optical modules use CWDM technology, which allows different wavelength optical signals to be multiplexed together through an external WDM multiplexer and transmitted over a single optical fiber, thus saving fiber resources. At the receiving end, a WDM demultiplexer is needed to separate the combined optical signals. DWDM optical modules, on the other hand, leverage DWDM technology to multiplex a larger number of optical signals with narrower wavelength spacing onto a single fiber. This enables higher transmission capacity compared to CWDM systems.

Coarse wavelength division multiplexing (CWDM) is a passive optical networking technology that multiplexes and demultiplexes multiple optical signals of different wavelengths onto a single fiber strand. It utilizes a broader wavelength spacing of 20 nm compared to dense wavelength division multiplexing (DWDM) systems. CWDM operates within a wavelength range of 1270nm to 1610nm, enabling the transmission of multiple data streams over a single fiber. CWDM optical modules are categorized into two types based on their transmission distance capabilities: Long-haul CWDM modules (10km or greater): These modules typically employ the posterior wavelength band (1470nm to 1610nm) to achieve extended transmission distances, typically up to 40 km or more. Short-haul CWDM modules (less than 10 km): These modules utilize the full wavelength band (1270nm to 1610nm) to support shorter transmission distances, typically around 10 km or 20 km.

CWDM optical modules are commonly employed within CWDM systems, offering a cost-effective alternative to DWDM optical modules. They are widely used in various applications due to their advantages in terms of cost and versatility.

Deployment of CWDM optical modules:
Installation in Switches: CWDM optical modules are typically installed within switches, enabling them to connect to the network.

Connection to CWDM Multiplexers/Demultiplexers (CWDM MUX/DEMUX) or Optical Add-Drop Multiplexers (OADMs): Using patch cords, CWDM optical modules are connected to CWDM MUX/DEMUX or OADM devices. These devices facilitate the multiplexing and demultiplexing of optical signals, allowing multiple data streams to be transmitted over a single fiber strand.

SAN/NAS Storage Networks
SAN (Storage Area Network) and NAS (Network Attached Storage) are two prent network-based storage solutions that facilitate shared data access for multiple users and applications. While both technologies serve the fundamental purpose of data storage and management, they differ significantly in their architecture, performance characteristics, and typical applications.

A SAN is a dedicated high-speed network that interconnects servers with storage devices, providing block-level access to data. It operates independently from the local area network (LAN) and typically employs Fibre Channel or iSCSI protocols for communication. SANs are designed for high-performance, mission-critical applications that demand low latency and high throughput.

Key components of a SAN:
Servers: The computing systems that process and utilize the stored data.
Fibre Channel Switches: Specialized network devices that facilitate data exchange between servers and storage devices.
Storage Devices: Hardware units that store and manage data, such as hard disk drives (HDDs) or solid-state drives (SSDs).
Transceivers (Optical Modules and Fiber Optic Cables): The physical components that transmit data signals over fiber optic cables.

5G Transport Network
Optical modules play a pivotal role in interconnecting devices across each layer of the 5G transport network. They convert electrical signals into optical signals for transmission over fiber optic cables and vice versa. These modules are essential for enabling seamless data communication throughout the network.

The 5G fronthaul network mainly uses 25G SFP28 (eCPRI/CPRI) optical modules, including dual-fiber bidirectional, single-fiber BiDi, and 25G WDM (including tunable wavelength) modules.

Short-Reach Optical Modules: These modules are typically used for intra-device or short-distance connections within the same building or campus. They operate at lower speeds but offer lower costs and power consumption.

Long-Reach Optical Modules: These modules are designed for longer-distance transmissions, typically over several kilometers or even hundreds of kilometers. They operate at higher speeds to support the demands of 5G applications.

High-Speed Optical Modules: These modules are the most advanced type, capable of transmitting data at ultra-high speeds to support the most demanding 5G applications, such as ultra-reliable low-latency communication (URLLC) and immersive extended reality (XR).
The 5G fronthaul network, responsible for connecting radio access units (RAUs) to baseband units (BBUs), plays a crucial role in enabling the high-speed, low-latency communication that is essential for 5G applications. Among the various optical modules employed in the 5G fronthaul network, 25G SFP28 (eCPRI/CPRI) modules stand out as the primary choice due to their versatility, performance, and cost-effectiveness.

The 5G midhaul primarily uses 25G, 50G, 100G, 200G, and 400G optical modules, supporting various interface protocols such as CPRI, eCPRI, Ethernet, and OTN, as well as modulation formats like NRZ, PAM4, and DMT.

The demand for optical modules is primarily driven by two key markets: data communication and telecommunications. In today's data-driven era, optical modules are poised to witness a surge in new growth opportunities.