Gigahertz-bandwidth optical memory in Pr 3+ :Y 2 SiO 5

Abstract

We experimentally study a broadband implementation of the atomic frequency comb (AFC) rephasing protocol with a cryogenically cooled P r 3 + : Y 2 S i O 5 crystal. To allow for storage of broadband pulses, we explore a novel, to the best of our knowledge, regime where the input photonic bandwidth closely matches the inhomogeneous broadening of the material ( ∼ 5 G H z ) , thereby significantly exceeding the hyperfine ground and excited state splitting ( ∼ 10 M H z ) . Through an investigation of different AFC preparation parameters, we measure a maximum efficiency of 10% after a rephasing time of 12.5 ns. With a suboptimal AFC, we witness up to 12 rephased temporal modes.