  Photonic and optoelectronic devices may offer the opportunity to realize
efficient signal processing at speeds higher than in conventional electronic
devices. Switches form the building blocks for circuits and fast photonic
switches have been realized [1,2,3,4,5,6]. Recently, proof of principle of
exciton optoelectronic devices was demonstrated [7,8]. Potential advantages of
excitonic devices include high operation and interconnection speed, small
dimensions, and the opportunity to combine many elements into integrated
circuits. Here, we demonstrate experimental proof of principle for the
operation of excitonic switching devices at temperatures around 100 K. The
devices are based on an AlAs/GaAs coupled quantum well structure and include
the exciton optoelectronic transistor (EXOT), the excitonic bridge modulator
(EXBM), and the excitonic pinch-off modulator (EXPOM). This is a two orders of
magnitude increase in the operation temperature compared to the earlier
devices, where operation was demonstrated at 1.5 K [7,8].
