Great improvement of phase controlling of the entirely independent stimulated Brillouin scattering phase conjugate mirrors by balancing the pump energies

For developing a beam combination laser with the stimulated Brillouin scattering-phase conjugate mirrors (SBS-PCMs), the phase control of the backward SBS waves is essentially required. We proposed a new effective and practical technique in previous works, in which entirely independent SBS-PCMs are used, so that there is no limit of the number of the beams for the beam combination laser. In this letter, we show that in the proposed technique, the phase of the SBS wave significantly depends on the pump energy and it can be stabilized—although the independently separate SBS-PCMs are used—provided that the pump energies are balanced under the density modulation. In this experimental work, the standard deviation of the relative phase difference between the SBS waves has been reduced less than λ∕30 by the amplitude dividing method to provide the pump beams with the nearly same energies.