High-speed monolithic GaInAs twin- pin photodiode for balanced optical coherent receivers

A high-speed, monolithic GaInAs twin-pin photodiode has been fabricated for balanced optical coherent receiver applications. A very small capacitance of 80 fF, a high quantum efficiency of 80% and −3dB cutoff frequency of more than 13 GHz have been achieved. An intensity modulation suppression of −30 dB has been measured up to 7 GHz, which provides evidence of an excellent balance between the characteristics of the two photodiodes.