Cladding layer thickness-controlled directional coupler optical switch

The AlGaAs/GaAs cladding layer thickness-controlled directional coupler optical switch (CTC-SW) is discussed. To increase the efficiency of coupling between two waveguides, the CTC-SW was designed with a thin i-AlGaAs cladding layer h between the two waveguides. The coupling length L/sub c/ can be reduced, without reduction of the extinction ratio and increase of the switching voltage. For instance, L/sub c/ of CTC-SW (h=0.07) can be reduced 40% more than that of a conventional directional coupler switch (h=0). The extinction ratio is near 20 dB, both for the crossover (applied voltage V=0 V) and straight-through (V=19 V) states. A technique for adjusting L/sub c/ to the device length was developed.<
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