Cryogenic Primary Standard for Optical Fibre Power Measurement
Malcolm G. White, Zeus Ruiz, Christopher S. Yung, Igor Vayshenker, Nathan A. Tomlin, Michelle S. Stephens, John H. Lehman
NIST has completed commissioning a new, state-of-the-art cryogenic primary standard for optical fibre power measurement and calibration. It establishes for the first time, a direct traceability route between the device under test and primary standard. Two silicon micro- machined planar detectors, with vertically aligned carbon nanotube absorbers, thin film tungsten heaters and superconducting resistive transition edge temperature transducers, form the basis of the radiometer. Magnetic phase change thermal filters ensure noise-free operation at 7.6 K. Measurement repeatability below 50 ppm is routinely achieved during an autonomous measurement cycle of 30 minutes. The expanded measurement uncertainty at k = 2 is 0.4 %, a 20 % improvement on NISTs current Calibration and Measurement Capability. We verified the performance of the new standard by comparing it to our current standard using four transfer detectors at nominal wavelengths 850 nm, 1295 nm and 1550 nm. The comparison agreed within the combined expanded measurement uncertainty of 0.65 %. Whilst the new standard is intended primarily to service the telecommunications industry, it is limited only by available sources and optical fibre.