The sensitivity of photoconductor receivers for long-wavelength optical communications.

We calculate the sensitivity of In0.53Ga0.47As photoconductor receivers for use in moderate to high bit rate lightwave transmission applications. It is found that the noise of photoconductive receiver is dominated at all bit rates B 4 Gb/s by Johnson noise in the conductive channel. Nevertheless, the total noise current decreases approximately linearly with photoconductive gain and therefore the sensitivity of photoconductive receivers can be comparable to high sensitivity pin photodiode receivers. The sensitivity of practical photoconductive receivers compares most favorably with pin receivers in the bit rate range of 500 to 2 Gb/s. However, receivers employing high speed In0. 53Ga0.47As/InP avalanche photodiodes are expected to be more sensitive than photoconductive receivers over the entire bit rate range considered.