[OPTICAL REVIEW Vol. 8, No. 2 (2001) 126-132]
Optimum Temporal Pulse Shape of Launched Light for Optical Time Domain Reflectometry Type Sensors Using Brillouin Backscattering
Hiroshi NARUSE1 and Mitsuhiro TATEDA2
1Access Network Service Systems Laboratories, NTT, 1-7-1, Hanabatake, Tsukuba, Ibaraki, 305-0805 Japan, 2Department of Information and Image Science, Faculty of Engineering, Chiba University, 1-33, Yayoicho, Inage, Chiba, 263-8522 Japan
(Received December 18, 2000; Accepted February 5, 2001)
We investigated numerically the relationship between the temporal shape of an optical pulse launched into an optical fiber and the power spectrum of the Brillouin backscattered light it produces. We analyzed the measurement error of the peak-power frequency of the Brillouin backscattered light power spectra obtained from the launched light with various pulse shapes. In this investigation and analysis, we characterized the pulse shape by the width, leading-trailing time, and steepness. Regardless of the launched pulse shape, the peak-power frequency-measurement error increases as the pulse width shortens. For identical launched pulse widths, a triangular pulse generates the Brillouin backscattered-light power spectrum with both the narrowest profile and the largest peak power, and consequently provides the minimum error when we measure the peak-power frequency. This shows that a temporally triangular pulse is the best for the launched light.
Key words : Brillouin backscattered light, power spectrum, pulse shape, launched light, error analysis, optical fiber measurement