The monitoring photodiode is the key building block for an optical triplexer at wavelengths of 1310, 1490, and 1550 nanometers. The InGaAs/InP photodetectors were proposed and fabricated to be monolithi-cally integrated with AlGaAs/GaAs optical waveguides using total internal reflection coupling. The metal coplanar waveguides on top of the polyimide planarization and passivation layer were then connected to illustrate the high speed monitoring functions. The full width half maximum of the temporal response and 3-dB bandwidth for the optical waveguide coupled photodiodes demonstrated 29.5 ps and 11 GHz, respectively. The bit error rate performance of this integrated photodiode at 10 Gbit/s with 2(7)-1 long pseudo-random bit sequence NRZ input data also showed error-free operation.