Noise Figure in Near-Infrared Amorphous and Mid-Infrared Crystalline Silicon Optical Parametric Amplifiers

The noise figures (NF) of near-infrared (near-IR) amorphous silicon (a-Si) and mid-infrared (mid-IR) crystalline silicon (c-Si) optical parametric amplifiers (OPA) are numerically investigated. The impact of nonlinear losses, i.e., two-photon absorption (TPA) and TPA-induced free carrier absorption (FCA), as well as Raman-effect-induced complex nonlinear coefficient are taken into account in a-Si OPAs. The amplified spontaneous emission (ASE) of Erbium-doped fiber amplifiers (EDFA) and the relative intensity noise (RIN) of the pump laser are considered as the dominant pump noises when simulating the pump transferred noise (PTN) of near-IR a-Si and mid-IR c-Si OPAs, respectively. It is shown that in typical near-IR a-Si OPAs, the NF is ~5 dB on the Stokes side but increases sharply to above 10 dB at the gain edge on the anti-Stokes side. In high-gain mid-IR c-Si OPAs, the NF is dominated by the PTN and is well above 10 dB at the gain edge. These results indicate that both near-IR a-Si OPAs and mid-IR c-Si OPAs are promising alternatives to near-IR c-Si OPAs, but they both have limitations in broadband operation.