Triple quantum well electron transfer infrared modulator

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Abstract
In this letter, we present a new bicolor infrared modulator using intersubband absorptions in quantum wells. The structure consists of two wells of different widths on either side of a reservoir of electrons. Depending on the sign of the electric field, the electrons transfer either into the wide well or into the narrow well, and then give rise to an intersubband absorption of the corresponding wavelength. With no applied bias, all the carriers are located in the reservoir and no absorption occurs in the midinfrared wavelength range of interest. Two samples are studied by transmission measurements in a Fourier transform infrared spectrometer. The great importance of the space charge effects in this type of device is evidenced and simulated by a self-consistent model.