A method is provided for co-site interference mitigation in an RF communication system. Spectral nulls created in an optical domain may be used to mitigate interfering signals in an RF signal. The method includes: receiving an RF input signal via an antenna; generating two optical signals that are each modulated using the RF signal; creating a phase delay in one of the two optical signals that corresponds with a spectral null at a frequency of an interfering signal; converting the two optical signals into two corresponding electrical signals and combining the two electrical signals to create spectral nulls via interference between the two signals and form a mitigated output signal. In this way, the spectral null offsets the amplitude of the interfering signal, thereby reducing the signal strength of the interfering signal.