Stimulated Brillouin Scattering

Our experiment setup is shown schematically in Fig. S1. We use two tunable continuous-wave diode lasers operating at wavelengths near 1.55 μm, with output frequencies offset by 9.6 GHz. The output intensities are modulated using Mach-Zehnder modulators to create the write, read and data pulses. The modulators are driven by two independent outputs of a pulse-pattern generator. We cascade three Erbium-doped fiber amplifiers to increase the peak power of the write and read pulses. The fiber loop formed by two 3-dB couplers, a 1-km-long single-mode fiber (SMF28e) and a fiber polarization controller is used to remove the weak coherent background and amplified-spontaneous-emission noise. It is a nonlinear transmission element adjusted to pass with high efficiency the write and read pulses and reject the weak background. The write and read pulses enter a 5-m-long highly nonlinear optical fiber – the stored-light medium – where they counterpropagate with respect to the data pulses that enter the fiber via a circulator. The write and read pulses are ~1.5 ns long, have a nearly rectangular shape as shown in Fig. S2, and have a peak power of ~100 W. They leave the fiber via another circulator and are attenuated before reaching a fast photoreceiver. The data pulses leave the fibe