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Schematic of the dispersive Fourier-transform imaging experiment based on amplified dispersive Fourier transformation. DCF: dispersion compensation fiber, and WDM: wavelength division multiplexer. The Raman-amplified DCF maps the spectrally encoded reflectivity profile of the sample into a temporal waveform, which is then captured by the photodetector and digitized by the oscilloscope.
Calibrated reflectivity profile of the sample (shown in the inset drawing) with the calibrated length axis above the figure. The sample is scanned by the piezoelectric transducer (PZT) with a ramp function. One end of the PZT is attached to the sample while the other end is anchored to a heavy mount. The fast displacement of the sample from the right to the left was clearly captured. Although the image acquisition period is , only 1 out of every 625 scans (1 scan every ) is plotted for clarity.
Improved sensitivity of the dispersive Fourier-transform imaging method enabled by distributed Raman post-amplification of a weak reflection signal from the sample at various pump powers. The otherwise invisible reflectivity profile is improved by the Raman amplification. The -axis is calibrated to be length whereas the -axis is the uncalibrated voltage measured by the photodetector.
Calibrated reflectivity profile of a test barcode with its known code pattern in the background and the calibrated length axis above the figure. The figure clearly shows a matched barcode pattern of 1001010100 captured within only .
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