The invention relates to a passive device for the coherent combination of at least two optical amplifiers. According to the invention, said device comprises an interferometer having at least four branches (B1, B2, B3, B4) and comprising optical means for separating and combining polarization, said means having four inlet-outlet ports that are respectively connected to a branch. The first branch comprises a first polarization means, a first optical amplifier and a first mirror; the second branch comprises a second polarization means, a second optical amplifier and a second mirror; the third branch comprises a third polarization means and a third mirror; the fourth branch (B4) is an inlet-outlet branch of the interferometer; and the first, second and third polarization means are designed such that a polarized optical beam entering respectively into the first, second or third branch and reflected by the mirror at the end of said branch forms a polarized optical beam that leaves said branch with a polarization that is orthogonal to the polarization of the polarized optical beam entering said branch.