High amplification and low noise achieved by a double-stage non-collinear Brillouin amplifier

We report a double-stage non-collinear Brillouin amplifier structure with high amplification and low noise, achieving an energy amplification of 6 × 10¹¹ and a signal-to-noise ratio of 10³ for an input signal of 5.5 × 10^-14J in the regime above the pump's stimulated Brillouin scattering threshold. The signal of the first-stage amplifier is efficiently amplified and separated from the noise output. The saturation amplification with noise suppressing is implemented in the second stage. The design principles of system parameters such as the intersection angle between the pump and signal beams, the pump energy, and the beam diameter are given.