传统的可见光通信(VLC)调光方案利用冗余的补偿符号实现调光控制, 导致传输效率低。为了提高VLC系统传输效率, 提出一种基于整形极化码的调光控制方案, 通过预编码器改变码字中“1”出现的概率, 从而在无需添加冗余补偿符号的情况下实现调光控制功能。实验结果表明: 相比通过补偿符号实现调光控制的极化码方案, 整形极化码方案具备更高的传输效率和更好的纠错性能, 在25%和12.5%这2种典型的调光率场景中, 编码增益至少可以分别达到1.9 dB和3.3 dB。

针对强度调制直接检测-滤波器组多载波(IMDD-FBMC)系统中低比特位数数字模拟转换器(DAC)量化性能较差的问题，提出一种基于信号分布估计的非均匀量化方案。该方案采用基于FBMC信号分布的非线性规划方法获得量化误差最小时的量化阶距，进而提升基于低比特位数DAC的IMDD-FBMC系统性能。仿真结果表明:与均匀量化方式相比，该方案在3~5位量化比特位数的情况下可以使IMDD-FBMC系统的误码率(BER)性能提升15.9~60.7倍，且在保证系统性能的情况下，基于信号分布的量化方案可以减少1~2位量化比特位数，降低系统成本。

针对发射端频率选择性IQ(同相/正交相)不平衡对CO-OFDM(相干光正交频分复用)系统传输性能的影响,提出一种基于DF(判决反馈)的IQ不平衡估计算法,并与传统的PA(导频插入)算法进行了对比.仿真研究和理论推演表明,所提算法可以有效地估计IQ不平衡和信道参数,提高系统的BER(误码率)性能.

In this letter, two kinds of continuous wavelength-tunable light sources are achieved and investigated experimentally using a self-seeding reflective semiconductor optical amplifier (RSOA). Over 40 single mode wavelengths with 100 GHz spacing are generated by setting the parameters of the wavelength selective switch. The peak power of each wavelength reaches over 0.2 dBm with the signal-to-noise ratio (SNR) > 35 dB. The proposed schemes are appropriate for multi-wavelength-tunable light sources; the maximum number of wavelengths generated can reach to 4.

We propose a scheme for mitigating Rayleigh backscattering noise and demodulating differential phase-shift keying (DPSK) signals in wavelength-division-multiplexed passive optical networks (WDM-PONs) with injection-locked Fabry-Perot laser diodes (FP-LDs). Signal demodulation and wavelength conversion are simultaneously realized on the basis of the frequency deviation and red shift of longitude modes in the FP-LDs. Experimental results demonstrate that the demodulation and wavelength conversion of 2.5-Gb/s DPSK signals are achieved. A power penalty of about 1.6 dB at a bit error rate of 10-9 is measured after transmission over 25-km single mode fiber.

拓扑学上的光网络由边（光传输）和节点（光交换）组成。从业务属性出发，基于连接和无连接方式，分析了光交换的时间结构，包括光分组和光突发的时间结构，以及不同动态性的光电路交换的时长及其度量标准，结合实验结果分析了最短光电路交换的时长极限。从多端口和大容量的要求出发，重点讨论了基于微电子机械系统(MEMS)开关、波长选择开关(WSS)和阵列波导光栅(AWG)的三种光交换结构。分析了光交换结构的扩展方法，并讨论了光交换的几个具有挑战性的问题，包括缓存和能耗问题。通过分析，希望从时间和空间两个维度更清晰地认识光交换的本质及其与电交换的异同。

A spectral amplitude coded-optical code division multiplexing time division multiplexing (SAC-OCDM/TDM) passive optical network (PON) for upgrading the traditional TDM PON is proposed. To the best of our knowledge, our work is the first to report on the use of both spectral and orthogonal code domains, which are transparent to optical network unit (ONU) for hybrid PON, in order to upgrade TDM PON seamlessly. The fewer encoder/decoders and cheaper optical source under the conditions of high bite rate and large ONU accommodation make the system cost-effective. A downstream experiment is demonstrated, and the results demonstrate that the proposed system is feasible.

In wavelength-division multiplexing (WDM) ethernet passive optical networks (EPONs), to realize the statistical multiplexing of upstream wavelength resources, some optical tunable components are introduced in the optical network units. However, the switch latency (SL) of these tunable components constrains the performance of WDM-EPON. In this letter, we extend the mathematical model of the WDM interleaved polling with adaptive cycle time (IPACT) scheme by additionally considering the SL conditions. We also investigate the effect of channel SL on network performance. The simulation results show that the performance of WDM-IPACT-SL deteriorates as the SL increases.

We propose and demonstrate a simple configuration of wavelength-tunable fiber laser made up of a tunable band-pass filter, a Sagnac loop reflector, and a Fabry-Perot laser diode. Based on the self-seeded operation, the proposed fiber laser can obtain a single-longitudinal-mode output in the wavelength tuning range of 1544.69–1563.39 nm with tuning step of 1.34 nm. The performances of output power (>-9 dBm), optical side-mode suppression ratio (> 65.5 dB), and power and wavelength stabilities are well exhibited.

We propose a novel wavelength-division multiplexed passive optical network (WDM-PON) to simultaneously transmit unicast data and multicast services with upstream data re-modulation in optical network units (ONUs). For each wavelength channel in the optical line terminal (OLT), the downstream unicast data are applied to one arm of a dual-parallel Mach-Zehnder modulator (DPMZM) to generate baseband unicast non-return-to-zero (NRZ) signal. A radio frequency (RF) control signal is applied to the other arm to present two un-modulated sidebands for multicast data modulation in a differential phase-shift keying (DPSK) format. The flexible and dynamic multicast services are realized by simply switching the RF control signal on or off. The proposed scheme is experimentally demonstrated with 1.25-Gb/s downstream unicast, multicast, and upstream data.