Voltage tunable SiGe photodetector: a novel tool for crypted optical communications through wavelength mixing

G. Masini, L. Colace, F. Galluzzi, G. Assanto, T.P. Pearsall, and H. Presting

Appl. Phys. Lett. 70, 3194-3196 (1997)


We demonstrate a novel tandem SiGe-Si device which, based on different photoresponses in two back-to-back diodes, exhibits a voltage tunable spectral responsivity. This feature, in conjunction with a wavelength-dependence in the current direction, allows the efficient decryption of a signal when substantial noise is added to distinct carrier frequencies. Time dependent encryption schemes are also possible via a modulated voltage bias.