Waveguide-integrated InP/InGaAs/InAlGaAs MSM photodetectors

We report on novel waveguide-integrated MSM photodetectors with significantly enlarged coupling efficiency. This is achieved by using a vertically coupled In/sub 0.53/Al/sub 0.31/Ga/sub 0.16/As:Fe buried strip waveguide embedded in InP:Fe. The optical coupling efficiency from the guide into the photo-absorbing InGaAs:Fe was modeled using eigenmode calculations. The simulation results and the experimental data indicate that for an absorber thickness greater than 300 nm a coupling length as short as 15 /spl mu/m is sufficient for 95% absorption. The high vertical coupling efficiency is obtained without using an additional impedance matching layer.