Mechanism of a Variable Optical Attenuator Based on Guided Wave Resonance

The mechanism of an electrically controlled variable optical attenuator is investigated based on the varying energy coupling efficiency of a light beam into a guided wave resonance. Compared to the conventional attenuated total internal reflection devices based on the surface plasmon resonance, the driving voltage for this attenuator is greatly reduced because of the newly chosen working interior angle. This paper explains the principle of attenuator operation and presents experimental results obtained on a realization of the device.