We experimentally demonstrate that a type-II pulsed optical parametric amplifier operated in a phase-insensitive configuration works as a near-perfect classical optical amplifier whose noise figure approaches 3 dB at high gains. We further demonstrate that, when operated in a phase-sensitive configuration, this amplifier works as a quantum-optical amplifier whose noise figure goes below 3 dB and approaches 0 dB at high gains. The noise figure of 1.45 ± 0.2 dB, measured for a gain of 9 dB, is clearly in the quantum regime.
© 1993 Optical Society of America
J. A. Levenson, I. Abram, Th. Rivera, and Ph. Grangier, "Reduction of quantum noise in optical parametric amplification," J. Opt. Soc. Am. B 10, 2233-2238 (1993)