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Physical Review Letters

Broad-Band Parametric Deamplification of Quantum Noise in an Optical Fiber

Robert M. Shelby, M. D. Levenson, Stephen H. Perlmutter, Ralph G. DeVoe, Daniel F. Walls

Published Aug 11, 1986• 633 citations
Publisher

Abstract

Broad-band squeezed states of light are generated by forward nondegenerate four-wave mixing in a single-mode optical fiber cooled below 4.2 K. The minimum total noise level was (12.5 \ifmmode\pm\else\textpm\fi{} 0.5)% below the standard quantum limit.
DOI
10.1103/physrevlett.57.691

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Nondegenerate four-wave mixing in a single-mode optical fiber is proposed as a method of squeezed state generation. An analysis of the near-degenerate mixing process for forward propagation in realistic fibers is presented along with the theory of an experimentally feasible detection strategy. The effects of the quantum nature of the optical nonlinearity and absorption are modeled by treating the fiber medium as a collection of anharmonic oscillators. Methods of suppressing undesired effects such as stimulated Brillouin scattering are presented as is a technique for providing the phase-shifted local oscillator wave necessary for the detection of squeezing. Preliminary experiments on fiber characterization and the detection of four-wave parametric fluorescence are described.
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Forward nondegenerate four-wave mixing in an optical-fiber ring resonator is proposed as a method to generate squeezed states of light. The nonlinear interactions are analyzed both with a self-consistent propagation-equation technique and with Fokker-Planck equations in the Glauber-Sudarshan P representation. Excellent squeezing is predicted at modest input power levels, with perfect quantum-noise squeezing at the critical points for optical bistability. A method to suppress the stimulated Brillouin effect is proposed and demonstrated experimentally, and the effects of forward spontaneous guided acoustic wave Brillouin scattering inside the resonator are analyzed. Methods are suggested for minimizing this noise under conditions where squeezing can be detected. Experimental apparatus and procedures are outlined for verifying the predictions of our theory and demonstrating squeezing of classical and quantum noise.