Measurement of third-order optical nonlinear susceptibility using four-wave mixing in a single-mode ridge waveguide

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Abstract
Nondegenerate four-wave mixing in a single-mode ridge waveguide has been demonstrated as a technique for simultaneous measurement of the imaginary component and the absolute magnitude of the third-order nonlinear susceptibility χ(3). In the same experimenal apparatus, Im χ(3)(ω2 = ω1 + ω2 − ω1) was obtained by measuring the pump-induced probe power loss and |χ(3)(ω3 = ω1 + ω1 − ω2)| was derived from Stokes wave generation efficiency. The ratio of these quantities was obtained without significant system uncertainties. The technique has been applied to AlGaAs/GaAs quantum-well waveguides with picosecond laser pulses. For ħω1 ≈ ħω2 ≈ 1.43 eV, it was found that Im χ(3) = (6.1 ± 0.5) × 10−11 esu, |χ(3)| = (7.6 ± 1.7) × 10−11 esu with a system uncertainty of 25%, and Im χ(3)/|χ(3)| = 0.8 ± 31%, indicating the dominance of two-photon absorption.