A novel scheme of all-optical clock recovery from mutiwavelength non-return-to-zero （NRZ） data stream is proposed and demonstrated. The chirp induced by a chirped fibre Bragg grating and a semiconductor optical ampl...A novel scheme of all-optical clock recovery from mutiwavelength non-return-to-zero （NRZ） data stream is proposed and demonstrated. The chirp induced by a chirped fibre Bragg grating and a semiconductor optical amplifier is used to enhance the clock. The clock is recovered after injecting the enhanced signal into the scheme based on the stimulated Brillouin scattering. The experiment is carried out and the dual-wavelength clock is recovered. This novel scheme can realize clock recovery of multiwavelength NRZ signal in the total wavelength range of 3.3nm. This clock recovery technology is transparent to the data bit rate and modulation format, also without pattern dependence.展开更多
将散射信道建模为低莱斯因子衰落信道,并基于高斯近似和快速傅里叶变换推导了LDPC码在该信道中的误码率。针对差分进化中码字度分布值可能无效的问题,对算法进行修改并得到了优化的LDPC码。仿真结果表明推导的理论误码率与实际码字性能...将散射信道建模为低莱斯因子衰落信道,并基于高斯近似和快速傅里叶变换推导了LDPC码在该信道中的误码率。针对差分进化中码字度分布值可能无效的问题,对算法进行修改并得到了优化的LDPC码。仿真结果表明推导的理论误码率与实际码字性能非常接近,且优化后的不规则码相对规则码有0.5~0.7 d B的性能增益。展开更多
The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve ...The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve communication in non-line-of-sight (NLOS) transmission mode. Compared to line-of-sight (LOS) transmission, NLOS transmission does not require alignment and can be adapted to various underwater environments. The scattering coefficients of seawater at different depths are different, which makes the scattering of light in different depths of seawater different. In this paper, the received optical power and bit error rate (BER) of the photodetector (PD) were calculated when the scattering coefficients of blue-green light in seawater vary from large to small with increasing depth for NLOS transmission. The results show that blue-green light in different depths of seawater in the same way NLOS communication at the same distance, the received optical power and BER at the receiver are different, and the received optical power of green light is greater than that of blue light. Increasing the forward scattering coverage of the laser will suppress the received optical power of the PD, so when performing NLOS communication, appropriate trade-offs should be made between the forward scattering coverage of the laser and the received optical power.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 60437010.
文摘A novel scheme of all-optical clock recovery from mutiwavelength non-return-to-zero （NRZ） data stream is proposed and demonstrated. The chirp induced by a chirped fibre Bragg grating and a semiconductor optical amplifier is used to enhance the clock. The clock is recovered after injecting the enhanced signal into the scheme based on the stimulated Brillouin scattering. The experiment is carried out and the dual-wavelength clock is recovered. This novel scheme can realize clock recovery of multiwavelength NRZ signal in the total wavelength range of 3.3nm. This clock recovery technology is transparent to the data bit rate and modulation format, also without pattern dependence.
文摘将散射信道建模为低莱斯因子衰落信道,并基于高斯近似和快速傅里叶变换推导了LDPC码在该信道中的误码率。针对差分进化中码字度分布值可能无效的问题,对算法进行修改并得到了优化的LDPC码。仿真结果表明推导的理论误码率与实际码字性能非常接近,且优化后的不规则码相对规则码有0.5~0.7 d B的性能增益。
文摘The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve communication in non-line-of-sight (NLOS) transmission mode. Compared to line-of-sight (LOS) transmission, NLOS transmission does not require alignment and can be adapted to various underwater environments. The scattering coefficients of seawater at different depths are different, which makes the scattering of light in different depths of seawater different. In this paper, the received optical power and bit error rate (BER) of the photodetector (PD) were calculated when the scattering coefficients of blue-green light in seawater vary from large to small with increasing depth for NLOS transmission. The results show that blue-green light in different depths of seawater in the same way NLOS communication at the same distance, the received optical power and BER at the receiver are different, and the received optical power of green light is greater than that of blue light. Increasing the forward scattering coverage of the laser will suppress the received optical power of the PD, so when performing NLOS communication, appropriate trade-offs should be made between the forward scattering coverage of the laser and the received optical power.
