The electrical crosstalk between elements in a monolithic array of long wavelength p-i-n photodiodes is analyzed theoretically. It is shown that the parisitic capacitances in the external package are the dominant effects contributing to crosstalk, whereas resistive coupling leads to a negligible crosstalk. A general theory is derived to determine the effects of the capacitive coupling between channels on digital optical receiver sensitivity. The case of a raised cosine output waveform and an FET transimpedance amplifier is then considered to illustrate the tradeoff between crosstalk and receiver sensitivity. It is shown that the tradeoff may be optimized by varying the feedback resistance in a transimpedance amplifier.