RESUMO
This paper proposes a novel optical adaptive power transmission using automatic power control (APC)-erbium-doped fiber amplifier (EDFA) for turbulence-tolerant free-space optical (FSO) communications. Based on the quasi-stationary characteristics of turbulence channel and average power dependent optical gain features of EDFA, the channel state information (CSI) of the received upstream on-off keying (OOK) signal is optically conveyed to the orthogonally polarized transmitted downstream OOK signal with channel inversion via EDFA in APC mode. The performance is analyzed under various dynamic gain frequencies of APC-EDFA and different power ratios between downstream and upstream signals. Simulation results revealed that the power of downstream signal was adaptively transmitted according to the received upstream signal under effective turbulence suppression, transmitted power efficiency, and required SNR reduction without the estimation of CSI.
RESUMO
This paper proposes a polarization-dependent semiconductor optical amplifier (SOA)-based polarization shift keying (PolSK) modulation for turbulence-robust free-space optical (FSO) communication. Based on the nonlinear gain and polarization characteristics, the PolSK signal is modulated by the optical bit inversion using the polarization-dependent SOA and linear polarizer (LP). The capability of scintillation mitigation is analyzed under both balanced and polarization-independent SOA-based detections. The proposed technique is evaluated in experiments. The experimental results demonstrated that the bit-error-rate (BER) performance of the proposed technique was close to the conventional Mach-Zehnder modulator (MZM)-based PolSK modulation under various scintillation effects.
