Homodyne detection of coherence and phase shift of a quantum dot in a cavity.

A homodyne measurement technique is demonstrated that enables direct observation of the coherence and phase of light that passed through a coupled quantum dot (QD)-microcavity system, which in turn enables clear identification of coherent and incoherent QD transitions. As an example, we study the effect of power-induced decoherence, where the QD transition saturates and incoherent emission from the excited state dominates at higher power. Further, we show that the same technique allows measurement of the quantum phase shift induced by a single QD in the cavity, which is strongly enhanced by cavity quantum electrodynamics effects.

Analysis of subwavelength metal hole array structure for the enhancement of back-illuminated quantum dot infrared photodetectors.

This paper is focused on analyzing the impact of a two-dimensional metal hole array structure integrated to the back-illuminated quantum dots-in-a-well (DWELL) infrared photodetectors. The metal hole array consisting of subwavelength-circular holes penetrating gold layer (2D-Au-CHA) provides the enhanced responsivity of DWELL infrared photodetector at certain wavelengths. The performance of 2D-Au-CHA is investigated by calculating the absorption of active layer in the DWELL structure using a finite integration technique. Simulation results show that the performance of the DWELL focal plane array (FPA) is improved by enhancing the coupling to active layer via local field engineering resulting from a surface plasmon polariton mode and a guided Fabry-Perot mode. Simulation method accomplished in this paper provides a generalized approach to optimize the design of any type of couplers integrated to infrared photodetectors. Experimental results demonstrate the enhanced signal-to-noise ratio by the 2D-Au-CHA integrated FPA as compared to the DWELL FPA. A comparison between the experiment and the simulation shows a good agreement.

Fast, electrically controlled polarization modulation of multimode vertical-cavity surface-emitting lasers by RF frequency modulation.

We report on a study of polarization properties of asymmetric, multimode vertical-cavity surface-emitting lasers (VCSEL) subjected to electrical RF modulation. When subjected to RF modulation, complex frequency-dependent polarization properties, especially near the polarization switching point are revealed. We propose a scheme of rapidly switching the two RF frequencies modulating the VCSEL, in order to achieve fast polarization modulation in these VCSEL. Polarization modulation up to 300 MHz by modulating the RF frequency and up to 1.5 GHz with RF power modulation has been demonstrated; the fastest reported electrically controlled polarization modulation for multimode VCSELs.