High-Speed Evanescently-Coupled Waveguide Type-II MUTC Photodiodes for Zero-Bias Operation

We demonstrate evanescently-coupled GaAs _0.5 Sb _0.5 /In _0.53 AlyGa _0.47-y As modified uni-traveling carrier (MUTC) waveguide photodiodes (PDs) with high bandwidth (BW) of 66 GHz at zero bias and over 100 GHz bandwidth under low bias condition. An In _x Al _y Ga _1-x-y As dual-integrated waveguide-drift layer which can facilitate efficient light coupling from the waveguide into the absorber over a short length is utilized. A 7-μm long waveguide PD has an internal responsivity of 0.48 A/W at 1550 nm and clearly open eye diagrams at 40 Gb/s are demonstrated at zero bias.