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J. E. Sharping, M. Fiorentino,
P. Kumar
Opt. Lett.
26, 367-369 (2001)
Abstract
We report generation
of pulsed twin beams of light through optical parametric amplification
in a fiber Sagnac loop. By pumping the Sagnac loop with picosecond
pulses at a wavelength near the zero-dispersion wavelength of the
fiber, we achieve phase-matched nondegenerate four-wave mixing with
gain. For a gain of 2.2, the intensity noises of the amplified signal
and the generated idler (conjugate) pulses are found to be correlated
by 5.0 dB, and the subtracted noise drops below the shot-noise limit
by 1.1 dB (2.6 dB when corrected for losses). We have investigated
the gain dependence of the quantum-noise reduction as well as of the
intensity noises of the amplified signal and idler pulses. As the
gain increases, we observe the onset of excess noise on the idler
pulses.
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