Understanding SFP Optical Modules: Types, Selection, and Colour Code Insights
- tass peters
- 2 days ago
- 3 min read
Small Form-factor Pluggable (SFP) optical modules play a crucial role in modern networking, enabling flexible and efficient data transmission over fiber optic cables. Choosing the right SFP module depends on understanding its types, form factors, and the color codes that indicate key characteristics like wavelength and fiber type. This guide breaks down the common SFP optical modules, explains how to identify them by their pull-tab colors, and offers practical advice for selecting the right module for your network needs.
The Wavelength Can Be Identified by the Pull-Tab Color of the Optical Module
One of the easiest ways to identify the wavelength and fiber type of an SFP optical module is by looking at the color of its pull tab. This color coding helps technicians quickly recognize the module’s specifications and intended use without needing to check detailed labels or manuals.
Single Mode Optical SFP Modules
Single mode modules are designed for long-distance transmission and use specific wavelengths. Their pull-tab colors correspond to these wavelengths:
Blue pull tab: 1310 nm wavelength, suitable for Gigabit or 10G modules, with transmission distances between 20 and 40 kilometers.
Yellow pull tab: 1550 nm wavelength, used for longer distances, typically 40 kilometers or more.
Purple pull tab: 1490 nm wavelength, commonly found in Passive Optical Networks (PON).
Green pull tab: Modules designed for extreme long-distance transmission, 80 kilometers and above.
Red pull tab: Also 1550 nm wavelength, typically supporting distances around 40 kilometers.
Multi-mode Optical SFP Modules
Multi-mode modules are optimized for shorter distances and use a different wavelength:
Black pull tab: 850 nm wavelength, generally used for short-distance transmission up to 550 meters.
Specially Functional Modules
Some modules serve specialized purposes and have unique color codes:
Grey pull tab: Coarse Wavelength Division Multiplexing (CWDM) modules with wavelengths around 1470 nm or 1310 nm.
Orange/Brown pull tab: Single fiber bi-directional (BIDI) modules or specific CWDM wavelengths.
Colorless/Transparent pull tab: Test modules or unclassified fiber types.
Important Notes on Color Codes
Color coding is not fully standardized. Different manufacturers may use slightly different schemes, so always verify the module label or product manual.
CWDM modules have a more complex relationship between color and wavelength. For example, grey may correspond to 1470 nm, green to 1530 nm, and so on.
Common Optical Module Form Factors
Understanding the form factor is essential when selecting an SFP module, as it affects compatibility with networking devices.
1x9 Form Factor
This is one of the earliest optical module formats. It is slightly larger and less common today but still used in some legacy systems.
SFP (Small Form-factor Pluggable)
SFP modules are compact and hot-swappable, supporting speeds up to 1 Gbps. They are widely used in enterprise and data center networks.
SFP+
An enhanced version of SFP, SFP+ supports data rates up to 10 Gbps. It maintains the same physical size as SFP but offers higher performance.
QSFP+ (Quad Small Form-factor Pluggable Plus)
QSFP+ modules support 40 Gbps speeds by combining four channels in one module. They are common in high-performance computing and large data centers.
How to Select the Right SFP Optical Module
Choosing the right SFP module depends on several factors:
Transmission distance: Determine how far the signal needs to travel. Use multi-mode modules for short distances and single mode for longer distances.
Wavelength requirements: Match the module’s wavelength to your fiber type and network design. Use the pull-tab color as a quick guide.
Data rate: Ensure the module supports the required speed, whether 1 Gbps, 10 Gbps, or higher.
Compatibility: Check that the module is compatible with your networking equipment. Reliable manufacturers provide detailed specifications and compatibility lists.
Special functions: For networks requiring CWDM, BIDI, or test modules, select the appropriate color-coded module.
Practical Tips for Handling SFP Modules
Always handle modules by the edges to avoid contamination of the optical connectors.
Use dust caps when modules are not in use to protect the fibre interfaces.
Verify the pull-tab colour and label before installation to avoid mismatches.
Purchase modules from reputable manufacturers to ensure quality and reliability.
Summary
SFP optical modules come in various types and form factors, each suited to specific networking needs. The pull-tab colour provides a quick visual cue to the module’s wavelength and fibre type, helping technicians select the right module efficiently. Understanding these colour codes, along with the form factor and transmission requirements, ensures optimal network performance and compatibility. When selecting SFP modules, always verify details with product documentation and choose trusted manufacturers to maintain network reliability.
