An optical receiver converting an optical signal modulated by differential phase shift keying to electrical first and second data signals; generating a clock signal from the first data signal; demultiplexing the first data signal into two signals; latching the two signals using the clock signal; delaying the clock signal by a certain amount; latching the two signals using the delayed clock signal; demultiplexing the second data signal into two additional signals; generating an inverted clock signal by inverting the clock signal; latching the two additional signals using the inverted clock signal or the clock signal; and further latching the two additional signals using the delayed clock signal.