In order to meet the domestic length metrological requirements of optical time-domain reflectometer(OTDR),a fiber length standard based on the principle of the modulation phase shift technique is realized,which adopts a modular design,including the main system units such as the laser driver,signal modulation,photoelectronic conversion and frequency conversion,as well as the length measurement capability of 1 550 nm window.By independently measuring the fiber temperature correction coefficient and wavelength correction coefficient the normalized corrections of fiber length changes caused by different temperature and wavelength of the test light source in communication window are realized,compared to other research results of fiber length standard reported in China,as well as a complete uncertainty evaluation,which provide experimental evidences,new ideas and methods for the traceability of fiber length in the field of OTDR calibration.The measurement uncertainties are U=(0.016+7.2×10-6L)m(k=2)at 1310 nm,and U=(0.028+7.2×10-6L)m(k=2)at 1550 nm respectively.And the uncertainty of calibrating by this standard a 14 km fiber used to OTDR transmission standard is 0.13 m(k=2),which is twice as good as the original device.
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