Micro-optical waveguide on micro-actuating platform and its application in variable optical attenuator

We present a novel variable optical attenuator (VOA) using a new micro-optical waveguide (MOW) on micro-actuating platform (MAP) structure. The device consists of a fused biconical taper (FBT) coupler mounted on an electromechanical system where the axial stress over the waist of FBT coupler is precisely controlled. Its operation is based on change of coupling constant by compressive stress induced photoelastic effects on the waist zone. Three different types of devices operating near 1450 nm were fabricated with different cross-sectional morphologies at the FBT waists. The device with a circular cross section showed the highest stress sensitivity, where π phase shifts in the coupling constant were observed at an axial displacement of 9.5 μm. The proposed device showed a monotonic and continuous attenuation control up to 34.45 dB, with a very low PDL of 0.06 dB and a relatively low operating voltage of 15.3 V.