A novel long wavelength photodetector with dual-wavelength spectral response is designed and fabricated using a step-shaped Fabry-P′erot (F-P) filter structure. The step-shaped GaAs/AlGaAs distributed Bragg reflectors and the InP PIN photodetector are grown on a GaAs substrate using low pressure metal organic chemical vapor deposition. High quality GaAs/InP heteroepitaxy is realized by employing a thin low temperature buffer layer. The photodetector structure is optimized by theoretical simulation. This device has a dual-peak distance of 19 nm (1 558 and 1 577 nm). The 3-dB bandwidth of 16 GHz is simultaneously obtained with peak quantum efficiencies of 8.5% and 8.6% around 1 558 and 1 577 nm, respectively.