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Quadrature demodulation of a quantum dot optical response to faint light fields

2016; Optica Publishing Group; Volume: 3; Issue: 12 Linguagem: Inglês

10.1364/optica.3.001397

2334-2536

Galan Moody, Corey McDonald, A. Feldman, Todd E. Harvey, Richard P. Mirin, Kevin L. Silverman,

Quantum Information and Cryptography

The amplitude and phase of a material's nonlinear optical response provide insight into the underlying electronic dynamics that determine its optical properties.Phase-sensitive nonlinear spectroscopy techniques are widely implemented to explore these dynamics through demodulation of the complex optical signal field into its quadrature components; however, complete reconstruction of the optical response requires measuring both the amplitude and phase of each quadrature, which is often lost in standard detection methods.Here, we implement a heterodyne-detection scheme to fully reconstruct the amplitude and phase response of spectral hole-burning from InAs/GaAs charged quantum dots.We observe an ultra-narrow absorption profile and a corresponding dispersive lineshape of the phase, which reflect the nanosecond optical coherence time of the charged exciton transition.Simultaneously, the measurements are sensitive to electron spin relaxation dynamics on a millisecond timescale, as this manifests as a magnetic-field dependent delay of the amplitude and phase modulation.Appreciable amplitude modulation depth and nonlinear phase shift up to ~0.09× radians (16°) are demonstrated, providing new possibilities for quadrature modulation at faint photon levels with several independent control parameters, including photon number, modulation frequency, detuning, and externally applied fields.