Pump-to-Stokes relative intensity noise transfer in Brillouin amplifiers

Abstract

This paper proposes for the first time an analytical expression of the relative intensity noise (RIN) transfer in Brillouin amplifiers. Theoretical modelling and experimental measurements have been performed in the case of narrow linewidth pump. Introduction Stimulated Brillouin scattering (SBS) has been widely investigated in optical sensors, fibre lasers [1,2], slow light applications [3] and narrow-band filter realizations [4]. The two major sources of noise in SBS process are: the spontaneous amplified emission (ASE) and the pump-to-Stokes relative intensity noise (RIN) transfer. RIN transfer has been thoroughly studied in Raman amplifiers [5], whereas in Brillouin amplification, most of the research on noise performance is up to now focused on ASE. For RIN transfer in SBS, there have been literatures on RIN transfer in Brillouin lasers [1-2]. However, there have paid little attention on the impact of RIN transfer on the performance of SBS amplifiers, which are usually used to induce slow light propagation. In this paper, we study the RIN transfer in SBS pumped by narrow band pump. We firstly propose to address the problem with a frequency domain model. Afterwards, an analytical expression is derived to characterize the RIN transfer in the pump undepletion regime. This expression can be used to study the Brillouin amplifiers with broadband pump. Experimental measurements are performed by using a monochromatic pump modulated by an electrical sinusoidal generator. Study on RIN transfer both in the pump depletion and undepletion regimes show an excellent agreement between the experimental measurements and theoretical predictions. Theoretical model The RIN transfer in Brillouin amplifiers can be characterized by following frequency domain model, which is derived from the temporal domain one [6]: 2 2 2 p g B B p p s s E n g g i E E E Q E Q z c A A α ω ∂Δ − − Δ = − Δ − Δ − Δ ∂