Absorption Measurement Errors in Single-Mode Fibers Resulting From Re-Emission of Radiation

作者：Feng Yutong^*; Zhang Betty Meng; Zhao Junqing; Zhu Sheng; Price Jonathan H V; Nilsson Johan

来源：IEEE Journal of Quantum Electronics, 2017, 53(4): 6800611.

DOI：10.1109/JQE.2017.2708610

• Absorption
• fiber characterization
• spectroscopy

We investigate errors in small-signal absorption spectra that result from re-emission in single-mode fibers with overlapping absorption and emission spectra. Experiments on Er-doped fibers and simulations of Er-and Yb-doped fibers show that the re-emission can severely distort the spectrum, especially the peak, under common measurement conditions, and underestimate the absorption by well over 10% already at 30-dB peak absorption, if only the source or the detector is spectrally filtered. Re-emission can then be the dominant source of errors. The error increases for higher absorption and higher fiber-NA. For sufficiently high NA, a significant error remains even in the limit of zero absorption and reaches 5% at the peak of a 0.46-NA Yb-doped fiber. Furthermore, in contrast to the high-absorption case, the error is larger at longer wavelengths than at the peak. Simultaneous filtering of both source and detector with 0.1-nm bandwidth reduces the re-emission error to similar to 1% or less up to 90-dB absorption. Then, detector noise or saturation errors are likely to dominate and render re-emission errors insignificant. A standard amplifier model is well suited to the simulations of the rich physics of single-mode-fiber absorption measurements.

• 出版日期2017-8