Abstract: A method for isolating an optical signal comprising the following steps: receiving the optical signal from a transmitter with a receiver after the optical signal has propagated through a turbulent medium separating the transmitter from the receiver; splitting the received signal into first and second signals; filtering the first signal with an in-band spectral filter to create an in-band signal centered at an operating wavelength of the transmitter; filtering the second signal with an out-of-band spectral filter to create an out-of-band signal slightly out-of-band with respect to the operating wavelength of the transmitter; and subtracting the out-of-band signal from the in-band signal with a balanced detector in order to generate an output signal, whereby the output signal is a real-time representation of the intensity of the optical signal without background intensity.