PAPER DESCRIBES NIST SUPPORT FOR OPTICAL FIBER INDUSTRY.In response to rapid changes in fiber optic technology, 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. is developing techniques and standards to support the measurement of optical components and subsystems used in wavelength division multiplexed (known as WDM (1) (Wavelength Division Multiplexing) A technology that uses multiple lasers and transmits several wavelengths of light (lambdas) simultaneously over a single optical fiber. ) optical fiber communication systems. A new paper describes the development of wavelength calibration transfer standards and the accurate measurement of spectral response, dispersion, and polarization dependence of optical fiber and components. In the area of wavelength calibration, NIST has developed Standard Reference Material (SRM (1) (Storage Resource Management) The management of the storage resources in an organization in order to avoid duplication of files and to determine space utilization across all servers. ) transfer standards based on rotational-vibrational transitions in acetylene acetylene (əsĕt`əlēn') or ethyne (ĕth`īn), HC≡CH, a colorless gas. It melts at −80.8°C; and boils at −84.0°C;. and hydrogen cyanide molecules. The SRMs were designed for calibrating wavelength-measuring instruments such as optical spectrum analyzers and wavelength meters. New work is focused on molecules of carbon monoxide as an SRM for the new WDM-L band. NIST's spectral measurement system uses the calibrated wavelength meter and a tunable diode laser source to measure the transmittance and reflectance of WDM components. Wavelength filters are needed to remove amplified spontaneous emission Amplified spontaneous emission (ASE) or superluminescence is light, produced by spontaneous emission, that has been optically amplified by the process of stimulated emission in a gain medium. produced by the diode laser. NIST recently conducted a round robin measurement intercomparison to assess current measurement capabilities for wavelength filters. The agency is working with the Telecommunications Industry Association See TIA. (body, standard) Telecommunications Industry Association - (TIA) An association that sets standards for communications cabling. Cables that TIA set standards for include: EIA/TIA-568A and EIA/TIA-568B category three, four and five cable. to develop standard test procedures and evaluate measurement capabilities. Concerning chromatic dispersion, NIST has developed two systems to measure relative group delay which broadens pulses and limits the system data rate. One system is based on low-coherence interferometry; the other is a more conventional rf-modulated phase-delay method. After compensating for chromatic dispersion, the next significant mechanism for pulse-broadening is polarization-mode dispersion (PMD (Polarization Mode Dispersion) The type of dispersion that occurs in singlemode fiber due to a lack of perfect symmetry in the fiber and from external pressures on the cable. Light travels over singlemode fiber in two polarization states. ). NIST supports PMD metrology through two SRMs--SRM 2518, Polarization-Mode Dispersion (Mode-Coupled) and SRM 2538, Polarization-Mode Dispersion (Non-Mode-Coupled). |
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