Brillouin amplification of weak stokes signals from water based on a double-stage non-collinear system with mixture medium

A scheme is presented for amplifying weak Stokes signals from water using mixture medium of CS₂/CCl₄ in a double-stage non-collinear Brillouin amplification system. A frequency doubled Nd:YAG laser is used to produce single-mode pulses of 5.5-ns duration. Results show that choosing mixture liquid of CS₂/CCl₄ as amplifier medium has advantages over pure CS₂. Maximum gain can be obtained by changing the mixed ratio of medium to eliminate the difference of the Brillouin frequency shift between the generator and amplifier. Signal gain as high as 10¹¹ is experimentally achieved with an input signal of 8.6×10^-14J using the mixture of 90% CS₂ and 10% CCl₄ as the amplifier medium.