An optical data circuit includes threshold adjustment circuits to perform threshold adjustment compensation of asymmetrical optical noise. The optical data circuit includes an optical-to-electrical conversion circuit configured to produce first and second differential electrical data signals, at respective first and second electrical nodes, in response to an optical data signal. First and second digital-to-analog converter (DAC) circuits are each respectively coupled to the first and second electrical nodes and configured to respectively generate first and second adjustment signals. The first and second DAC circuits are configured to adjust the first and second differential electrical data signals such that a zero-crossing point of positive data is pulled up in response to the first adjustment signal and a zero-crossing point of negative data is pulled down in response to the second adjustment signal.