DFB stands for Distributed Feedback Laser. A single-mode laser with stable wavelength characteristics widely used in medium- and long-reach transceivers. The term is most useful when a project connects that definition to a concrete use case such as 1310/1550 nm single-mode optics.
The reference framework matters when specifying DFB for 1310/1550 nm single-mode optics. Values should be read from the product data sheet together with the measurement method and the limits required by IEEE, ITU-T, or the applicable MSA. A product name or quotation that mentions DFB without that context is not yet a complete requirement.
DFB should not be treated as another name for VCSEL. DFB is defined here as a single-mode laser with stable wavelength characteristics widely used in medium- and long-reach transceivers. By comparison, VCSEL means a compact laser commonly used with multimode fiber for cost-effective short-reach optical links. The two concepts may appear in the same design, but they answer different engineering or purchasing questions.
When selecting or documenting DFB, verify test wavelength, temperature, pattern, data rate, reference receiver, measurement uncertainty, and guaranteed limits. A common mistake is to assume that support for EML automatically confirms support for DFB; the exact data sheet, host configuration, and test conditions must show that relationship.
Frequently Asked Questions
How is DFB different from VCSEL?
DFB refers to a single-mode laser with stable wavelength characteristics widely used in medium- and long-reach transceivers. VCSEL instead refers to a compact laser commonly used with multimode fiber for cost-effective short-reach optical links. They can be related in one project, but one does not prove compliance with the other.
Where is DFB normally used?
Typical use includes 1310/1550 nm single-mode optics. The exact implementation still depends on the host equipment, link design, environment, and governing specification.
What should a DFB specification include?
It should state test wavelength, temperature, pattern, data rate, reference receiver, measurement uncertainty, and guaranteed limits. These details allow a supplier or engineer to verify the requirement instead of relying only on the term DFB.
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