What are the most common single-mode wavelengths used by OTDRs?

The most commonly used single-mode wavelengths for Optical Time Domain Reflectometers (OTDRs) are indeed 1,310 nm and 1,550 nm. These specific wavelengths are favored due to their optimal performance characteristics in single-mode optical fibers.

At 1,310 nm, the attenuation is relatively low, facilitating longer-distance measurements while providing a good balance of cost and performance. This wavelength is particularly beneficial for medium-distance applications, such as local area networks (LANs) or metropolitan area networks (MANs).

At 1,550 nm, the attenuation is even lower due to minimal water absorption in the glass, making it ideal for long-distance telecommunications networks. This wavelength is commonly used in long-haul fiber optic communication systems, such as those deployed by telecommunication companies.

Utilizing these wavelengths allows OTDRs to effectively assess the integrity and performance of fiber optic links, making them the industry standard for testing and monitoring optical fibers in various applications.