Multimode fibers, optical amplifiers and regenerators all communicate at wavelengths outside normal traffic windows. 1625 is ideal due to the transmission properties of optical fiber. This wavelength is used in a variety of applications requiring high power stable IR radiation. In optical communication systems it is often necessary to test fiber while the optical link is carrying live. The OTDR transmits a light pulse based on the wavelength while the fiber link is operational. The filtered 1625 nm or 1650 nm wavelengths could be vital for in-service maintenance and evaluation, eliminating the interference of live traffic. In fiber optic systems, specific optical wavelength bands are used based on performance, attenuation, and compatibility with amplification technologies.
