Photodiodes With Monolithically Integrated Wilkinson Power Combiner

We report the output power and linearity characteristics of two InP/InGaAs partially-depleted-absorber photodiodes monolithically integrated with a Wilkinson power combiner. Compared to a single photodiode an increase of 3 dB in output power is achieved and improved intermodulation distortion, as denoted by the figure of merit, OIP3, is observed in the frequency range up to 20 GHz. We also show that discrete photodiodes with single-stub tuning have improved OIP3 over a frequency range of a few GHz at the expense of reduced output power compared to those without tuning circuits. A model which provides good fits to the frequency dependence of the enhanced OIP3 is developed.