A laser cavity closed via the first-order diffracted light of an intracavity acousto-optic modulator is referred to as a frequency-shifted feedback laser laser. It has been proven that the laser output consists of a chirped frequency comb evenly spaced at a cavity-free spectral range. In this letter a phase correlation between the chirped comb components is discussed. A homodyne experiment with a Mach–Zehnder interferometer was carried out to examine the problem. It was clarified that the comb components are highly correlated in phase. ©1998 American Institute of Physics.