1550nanometer

1550 nanometer, often written as 1550 nm, is a wavelength in the near-infrared part of the electromagnetic spectrum. It corresponds to 1.55 micrometers, and in vacuum has a frequency of about 1.93 × 10^14 hertz. In transparent media such as silica, this wavelength propagates with relatively low loss compared with many other telecom bands.

In optical fiber communications, 1550 nm lies within the low-attenuation window of conventional silica fibers, where optical loss is around 0.2 dB per kilometer. This makes it well suited for long-distance transmission, especially when used with erbium-doped fiber amplifiers (EDFAs) that efficiently amplify signals in this band. The zero-dispersion wavelength of standard silica fibers is near 1300 nm, so channels around 1550 nm typically require dispersion management to maintain signal integrity over long distances.

Light sources and detectors for 1550 nm include semiconductor and fiber lasers, including distributed feedback and external-cavity designs, and InGaAs photodiodes for detection. The technology forms the backbone of modern telecommunication networks, particularly dense wavelength-division multiplexing (DWDM) systems that carry many channels on a single fiber.

Beyond telecommunications, 1550 nm is used in sensing and measurement applications. This wavelength is favored in some eye-safe free-space and lidar applications, as well as in certain spectroscopy setups where infrared access is required and eye safety considerations are important.

Standardization and safety: The 1550 nm region is addressed by ITU-T recommendations for fiber-optic transmission, including standards such as G.652 for standard single-mode fibers. Safety guidelines reference infrared exposure limits appropriate for 1550 nm sources.