Long-distance underwater optical wireless communication with PPLN wavelength conversion

摘要

In this thesis, we designed and experimentally demonstrated a high-power high-speed underwater optical wireless communication (UOWC) system with wavelength conversion construction 1,2. External modulation based on 1064nm laser is used for high-speed information communication, as well as the optical amplifier is used to obtain enough optical power of 1064nm laser. After that, according to the quasi-phase-matching (QPM) conditions, the PPLN optical structure is designed to improve the wavelength conversion efficiency for achieving higher 532nm laser output power in 24.5°C～40°C. Compared to the 532nm LD modulation system, this system can output 1.4W 532nm laser power in lOOMbps. This system experiments in single link 100m water tap of the attenuation coefficient 0.73dB/m equivalent to the clear ocean, and the measured bit error rate (BER) is 6.2×10~(-6) in 100Mbps pseudo-random binary sequence (PRBS) data without the forward error correction (FEC). Based on receiver sensitivity and the seawater channel optical transmission model, the transmission performance was predicted to be 340m@100Mbps and 100m@2Gbps in the attenuation coefficient equivalent to pure seawater.