NIST researchers measure wavelength-dependent gain of raman fiber optical amplifiers. (News Briefs).Staff at NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. recently completed measurements of the dependence of Raman gain in optical fiber on both the difference between the pump and signal wavelengths and the absolute pump wavelength. These measurements, made on four standard telecommunication fibers, represent the first direct measurements of the pump-wavelength dependence. The pump-wavelength dependence was measured using two complimentary techniques; a brute-force comparison of the Raman gain at different pump wavelengths and a simpler, more elegant comparison of the asymmetry Asymmetry A lack of equivalence between two things, such as the unequal tax treatment of interest expense and dividend payments. in the Stokes and anti-Stokes Raman gain at a fixed pump wavelength. Fiber Raman amplifiers Pronounced "ruh-mahn," it is a device that boosts the signal in an optical fiber by transferring energy from a powerful pump beam to a weaker signal beam. It relies on the interaction between light and atoms in the fiber. are becoming increasingly important in optical fiber communication systems since they provide both lower noise performance and a wider wavelength coverage than conventional optical amplifiers A device that boosts light signals in an optical fiber network. Unlike regenerators, which have to convert light to electricity in order to amplify it and then convert it back again to light, the optical amplifier amplifies the light signal itself. . In fiber Raman amplifiers, a strong pump laser A laser used as the pump for an optical amplifier or other laser. See EDFA and laser. provides gain to signals at longer wavelengths through stimulated Raman scattering Raman scattering or the Raman effect is the inelastic scattering of a photon. When light is scattered from an atom or molecule, most photons are elastically scattered (Rayleigh scattering). within the optical transmission fiber. The Raman gain will depend strongly on the wavelength difference between the pump and signal beams and weakly on the absolute pump wavelength. Previous measurements of the Raman gain have focused on its strong dependence on the wavelength difference between the pump and signal beams and have ignored the weaker pump-wavelength dependence. With the growing potential for widespread use of fiber Raman amplifiers in deployed systems, more complete measurements of the Raman gain are needed to provide input for system simulations. CONTACT: Nathan Newbury, (303)497-4227; nnewbury@boulder.nist.gov. |
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