An OTDR (Optical Time-Domain Reflectometer) utilizes multiple wavelengths, selected based on the type of fiber being tested (multimode or single-mode) and the application. There isn't a single fixed number; it varies depending on testing needs.
Wavelengths Used in OTDR Testing
OTDRs don't have a fixed number of wavelengths; rather, they are designed to operate at specific wavelengths commonly used in optical fiber communication. These wavelengths are chosen because of their transmission characteristics within the fiber.
Multimode Fiber
- 850 nm: Typically used for short-distance multimode fiber links, like in data centers.
- 1300 nm: Another wavelength option for multimode fiber, useful for different distance ranges compared to 850 nm.
Single-Mode Fiber
- 1310 nm: A common wavelength for general-purpose single-mode fiber testing.
- 1550 nm: Often used for long-haul single-mode fiber links due to lower attenuation.
- 1625 nm & 1650 nm: These wavelengths are frequently used for live fiber testing to avoid disrupting communication signals carried on the 1310 nm and 1550 nm wavelengths. They can also be used for more sensitive bend detection.
Factors Influencing Wavelength Selection
The specific wavelength chosen for an OTDR test depends on several factors:
- Fiber Type: Multimode or single-mode.
- Application: Installation, maintenance, or troubleshooting.
- Distance: Shorter or longer fiber links.
- Attenuation characteristics of the fiber.
- Whether the fiber is live or dark: Live fiber testing requires wavelengths that won't interfere with existing communications.
Conclusion
OTDRs don't have a fixed number of wavelengths. They are equipped to operate at different wavelengths (850nm, 1300nm, 1310nm, 1550nm, 1625nm, 1650nm), with the specific wavelength selected based on the fiber type and application.
