The optical module is a photonic and optoelectronic device composed of photonic electronic components, functional circuits, and optical interfaces used for optical-electrical conversion and electrical-optical conversion. The photonic electronic components include the transmitting and receiving ends. The transmitting end converts electrical signals into optical signals, which are then transmitted via optical fibers. The receiving end converts the optical signals back into electrical signals, thus enabling intercommunication between optics and electronics. Due to its high speed, high bandwidth, and low latency advantages, the optical module, although small in size and relatively simple in structure, requires high technical requirements. With the rapid growth of internet traffic in recent years, the market demand for optical modules has also been expanding rapidly.

Optical module type

Package form

Optical modules are divided into the following common types according to packaging form: SFP, SFP+, SFP28, QSFP+, QSFP28 and QSFP-DD.

• SFP optical module is an upgraded version of GBIC, with a maximum speed of up to 4.25G. It is mainly composed of lasers and is characterized by small size and hot-swappable.
• SFP+ optical module is an enhanced version of SFP with a transmission rate of 10Gbps, which can meet the application of 8.5G fiber channel and 10G Ethernet.
• The SFP28 optical module boasts a transmission rate of 25Gbps, along with a range of benefits such as low power consumption, high port density, and support for hot swapping.
• The QSFP+ optical module has a transmission rate of 40Gbps, supports MPO optical fiber connectors and LC optical fiber connectors, and is characterized by small size and hot-swappable.
• The QSFP28 optical module employs a four-channel configuration, each channel transmitting at 25Gbit/s in parallel, thus achieving a total transmission rate of 100Gbps，meeting the application of 100G Ethernet.
• The QSFP-DD optical module has a rate of 200Gbps and 400Gbps, using 8*25Gbit/s channels and 8*50Gbit/s channels respectively.

Central wavelength

The operating wavelength of an optical module is a range, but we are generally accustomed to using the center wavelength instead of the operating wavelength for description. According to the different center wavelengths, optical modules can be divided into ordinary optical modules and colored optical modules. The center wavelengths of ordinary optical modules are 850nm, 1310nm and 1550nm, while the center wavelengths of color optical modules include CWDM wavelength and DWDM wavelength. The CWDM wavelength range is 1270~1610nm, and the DWDM wavelength range is 1525~1565nm or 1570~1610nm. The wavelength is Color optical modules with CWDM wavelengths are called rough-wave optical modules, and color optical modules with DWDM wavelengths are called dense-wave optical modules. In the same band, there are more types of dense wave optical modules, so the dense wave optical modules make fuller use of the band resources. Light with different central bands can be transmitted in the same optical fiber without interfering with each other, effectively saving optical fiber lines. Color optical modules are mainly used in long-distance transmission lines.

Interface Type

Optical modules are equipped with either optical fiber interfaces or RJ45 interfaces. Optical fiber interfaces are commonly used for connecting optical fiber jumpers with LC, MTP/MPO, and other connectors. Such optical modules are typically referred to as optical port modules. In contrast, RJ45 interfaces are used for connecting network cables, and the type of optical module equipped with these interfaces is known as an electrical interface module. The primary distinction between electrical and optical port modules lies in the transmission media they use. Electrical port modules transmit electrical signals, while optical port modules transmit optical signals.

Application areas

Optical modules can be classified into various categories based on their applications. These categories typically include SDH optical modules, fiber channel optical modules, Ethernet optical modules, and digital video optical modules.

• SDH optical modules are primarily deployed in SDH/SONET networks, including popular Gigabit SFP optical modules, 10G SFP+ optical modules, and others.
• Fibre Channel optical modules are primarily employed in data centres for connecting Fibre Channel storage network links. They stand out for their compact size, low energy consumption and hot-swappable design that caters to swift transmission of copious amounts of data.
• Ethernet optical modules are mainly used in local area networks, such as common ordinary optical modules, WDM optical modules and BiDi optical modules.
• Ethernet optical modules are a staple in local area networks, encompassing a range of options such as standard optical modules, WDM optical modules, and BiDi optical modules.
• Digital video optical modules are primarily utilized in PDH optical transceivers and high-definition video transmissions. These modules are compact and designed for hot-swapping, allowing for quick and efficient replacement.

In brief, the optical module is a crucial piece of equipment that facilitates both optical and electrical transmissions. Its exceptional features like high speed, bandwidth, and low latency make it an invaluable tool in computer networks, communication systems, data centers, and other fields. Additionally, the variety of optical module types available provides flexibility and caters to the unique demands of diverse applications.