Investigation on the noise suppression of Brillouin amplification for weak Stokes signals

For weak Stokes Brillouin amplification, the speckle noise of the amplified spontaneous Brillouin scattering (ABS) of pump laser limits the signal to noise ratio (SNR). This paper introduces the design of a double signal Brillouin amplification scheme, it can improve the SNR for weak signal Brillouin amplification. The experimental results show that the non-collinear strong Stokes Brillouin amplification can reduce ABS noise by more than two orders of magnitude, the collinear weak Stokes signal optical magnification decreases only one order of magnitude, nJ collinear weak signal can still get 10⁵ magnification. Double signal Brillouin amplification scheme can substantially in the amplified signal, at the same time, can effectively improve the optical SNR, and improve the reliability of signal measurement.