METHOD OF LOGICALLY COMBINING OPTICAL SIGNALS

摘要

Optical signals of individual wavelengths are logically combined by directing the signals at an incident surface of an integrated series of photodiodes each comprising an undoped light-absorbing semiconductor region which absorbs a high proportion of a respective one of the individual wavelengths and a low proportion of the other individual wavelengths.
Each of the integrated series of photodiodes consists of an undoped light-absorbing semiconductor region contiguous with one component region of a pair of doped semiconductor regions forming a quantum mechanical tunnelling pn junction, the combined thickness of the pair of doped semiconductor regions being of the order of the mean a free path length of a charge carrier therein. The undoped light-absorbing region of a succeeding diode in the series is contiguous with the other component region of the pair of doped semiconductor regions of the preceding diode in the series.