A method of synthesizing a modulated optical signal using a laser cascaded with an amplitude modulator. A phase drive signal V.sub.F(t) is derived for driving the laser to generate an optical carrier signal with a desired phase .phi.(t). An amplitude drive signal V.sub.S(t) is then derived for driving the amplitude modulator to impose a desired amplitude S(t) onto the optical carrier signal generated by the laser. The amplitude drive signal V.sub.S(t) is compensated for amplitude modulation of the optical carrier signal generated by the laser.