An apparatus for despreading in an optical domain configured to split a received optical signal into a first optical signal and a second optical signal, perform phase deflection on the second optical signal, output a third optical signal, perform phase deflection on the first optical signal and the third optical signal, output a fourth optical signal and a fifth optical signal to a balanced receiver, and superimpose the fourth optical signal and the fifth optical signal to generate a first electrical signal. A multiplication operation in conventional code division multiple access (CDMA) despreading is transferred from an electrical domain to an optical domain such that a chip rate can be easily raised to 20 gigahertz (GHz) or even to 25 GHz, a maximum rate of 100 gigabits per second (Gbps) can be provided in a single wavelength, and a user requirement for high bandwidth can be met.