Integration of polyimide waveguides with traveling-wave phototransistors

Polymer waveguides with low optical losses are becoming increasingly important for photonic circuits. Among these, polyimide waveguides have properties which distinguish them as a versatile interconnect medium for practical optoelectronic integrated circuits. We have integrated these waveguides with traveling-wave phototransistors (TW-HPT's) in which optical power transfer occurs through leaky mode coupling of light from the waveguide along the length of the device. Independent optimization of the waveguide and phototransistor is now possible permitting superior coupling efficiency and detector bandwidth. We present proof-of-concept results for a 2-mm-long TW-HPT integrated with a 8×10-μm polyimide waveguide.