OPTICALLY CONTROLLED S-SHAPED AND N-SHAPED NEGATIVE DIFFERENTIAL RESISTANCES BY RESONANT-TUNNELING TRIANGULAR-BARRIER OPTOELECTRONIC SWITCH(R-TOPS)

We report novel optoelectronic functions in a resonant-tunnelling tria ngular-barrier optoelectronic switch (R-TOPS). We successfully observe d optically controlled S- and N-shaped negative differential resistanc es (NDRs) simultaneously in a single device. Different types of optoel ectronic bistabilities originating from S- and N-shaped NDRs were obta ined by changing the input light power. We also obtained the different ial gain characteristics and latch characteristics from S-shaped NDR b y changing the bias voltages. These characteristics with their differe nt behaviours make it possible to realize novel optoelectronic switchi ng.