In this paper, we propose an encryption technique for underwater visible light communication (UVLC) based on chaotic phase scrambling (PS) and conjugate frequency hopping (CFH). The tec

In this paper, we propose an encryption technique for underwater visible light communication (UVLC) based on chaotic phase scrambling (PS) and conjugate frequency hopping (CFH). The technique is experimentally tested using 8-level pulse amplitude modulation (PAM-8) and a 1.2-meter underwater link. The security key of the phase scrambling code is generated according to a logistic map, and the frequency hopping is achieved by adding same zero frequency points to the signal spectrum. The maximum transmission rate of 2.1 Gbps is measured with the bit error rate (BER) below 7% the hard decision forward error correction (HD-FEC) threshold of 3.8×10^-3. show less

High-order dispersion introduced by Gires-Tournois interferometer mirrors usually causes spectral sidebands in the near-zero dispersion region of mode-locked fiber lasers. Here, we demo

High-order dispersion introduced by Gires-Tournois interferometer mirrors usually causes spectral sidebands in the near-zero dispersion region of mode-locked fiber lasers. Here, we demonstrate a sideband-free Yb-doped mode-locked fiber laser with dispersion-compensating Gires-Tournois interferometer mirrors. Both simulation and experiment demonstrate that the wavelength and energy of the sidebands can be tuned by changing (i) the transmission coefficient of the output mirror, (ii) the pump power, and (iii) the ratio of net cavity dispersion to net third-order dispersion in the cavity. By optimizing these three parameters, the laser can generate a sideband-free, Gaussian-shaped spectrum with a 13.56-nm bandwidth at -0.0232-ps2 net cavity dispersion, which corresponds to a 153-fs pulse duration.show less

A circular-sided square microcavity laser etched a central hole has achieved chaos operation with a bandwidth of 20.8 GHz without external optical feedback or injection, in which intens

A circular-sided square microcavity laser etched a central hole has achieved chaos operation with a bandwidth of 20.8 GHz without external optical feedback or injection, in which intensity probability distribution of chaotic signal with a two-peak pattern was observed. Based on the self-chaotic microlaser, physical random numbers at 400 Gb/s were generated by extracting the four least significant bits without other complex post-processing methods. The solidary chaos laser and minimal post-processing have predicted a simpler and low-cost on-chip random number generator in the future.show less

In the scheme of fast ignition of inertial confinement fusion, the fuel temperature mainly relies on the fast electrons, which acts as an energy carrier and transfers the laser energy t

In the scheme of fast ignition of inertial confinement fusion, the fuel temperature mainly relies on the fast electrons, which acts as an energy carrier and transfers the laser energy to the fuel. Both conversion efficiency from laser to fast electron and the energy spectrum of the fast electron are essentially important to achieve a high effective heating. In this manuscript, a two-dimensional particle in cell simulation is applied to study the generation of fast electrons from solid-density plasmas with different laser waveforms. The results have shown that the slope of the rising edge has a significant effect on the fast electron generation and energy absorption. For the negative skew pulse with a relatively slow rising edge, the J×B mechanism can most effectively accelerate the electrons. The overall absorption efficiency of the laser energy is optimized, and the fast electron yield in the middle and low energy range is also improved.show less