Summary form only given. Mixed type-I/type-II GaAs/AlAs double quantum wells (QW) offer a means of generating electron-hole pairs with a lifetime which can exceed 400 /spl mu/s. For the sample chosen for the measurements discussed here, electrons excited in the /spl Gamma/-valley of the narrow well are transferred to the X-valley in the barrier material and subsequently to the /spl Gamma/-valley of the wider well. The recombination rate of the spatially separated electron-hole pairs is dominated by the tunneling rate of holes from the narrow well into the wider well. This leads to an intrinsically long life-time of the spatially separated electron-hole pairs which enables large carrier densities (7/spl times/10/sup 11/ cm/sup -2/) to be excited with low optical power densities (0.07 W/cm/sup 2/). We have exploited these high carrier lifetimes and densities to build an optically controlled THz-modulator with large contrast ratios for extremely low optical power.


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    Title :

    An optically-driven THz-modulator


    Contributors:
    Necker, N.E. (author) / Libon, I.H. (author) / Hempel, M. (author) / Feldmann, J. (author) / Koch, M. (author) / Dawson, P. (author)


    Publication date :

    1999-01-01


    Size :

    296125 byte




    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English