Cladding Layer Impedance Reduction to Improve Microwave Propagation Properties in p-i-n Waveguides

The cladding layer effect on microwave propagation properties of semiconductor p-i-n waveguides is investigated in this letter. Through the optical excitation in quantum wells of p-i-n waveguides, high-speed photocurrent is used to examine the microwave propagation. Two devices of p-i-n waveguides with different cladding layers are fabricated and measured, showing that a higher speed is found in the waveguide of wider cladding width. Verified by the microwave propagation properties, the higher speed is mainly attributed to lower microwave propagation loss due to the lower impedance in the wider cladding layer, suggesting this kind of structure can be applied to high-speed waveguide-based devices