研究了基于半导体光放大器(SOA)结合延迟干涉仪(DI)结构的全光波长转换。分析了SOA-DI结构的工作原理和DI参数的作用, 进行了10 Gb/s和40 Gb/s归零码全光波长转换实验研究。实验结果表明, 基于SOA中交叉增益调制(XGM)效应实现的波长转换为反相转换, 输出信号消光比较低, 当工作速率较高时波长转换信号质量明显恶化。而SOA-DI结构可实现同相波长转换并可改善波长转换信号的消光比, 从而改善单个SOA实现波长转换的性能并提高系统的工作速率, 该结构还具有结构简单、可光子集成等优点。

研究了160 Gb/s 光时分复用(OTDM)系统的解复用技术。针对160 Gb/s速率的特点,对高非线性光纤(HNLF)的光纤环镜(NOLM) 特性及解复用进行了数值仿真。计算了低信号光时间抖动下解复用误码特性对时钟与信号的走离及时钟功率的依赖关系。计算了三种走离值消光比随时钟功率增加的变化趋势并给出：存在一个能获得最大的解复用窗口消光比、并能降低相邻信道串扰的合适的时钟功率范围。利用自制的基于电吸收调制器和压缩技术的超短光脉冲源建立了160 Gb/s OTDM实验系统,测量了不同信号光功率下NOLM的消光比,它基本不随信号增大而变化,在信号功率为7.3 dBm时仍大于23 dB。利用上述装置实现了无误码的160 Gb/s到10 Gb/s全光解复用。

A 16*10-Gb/s optical time-division-multiplexing (OTDM) system was demonstrated experimentally with a well-designed ultrashort pulse source based on an electro-absorption modulator (EAM) and nonlinear fiber compressor. The obtained 10-GHz stable and pedestal-free pulse train has 2-ps width, high extinction ratio, and low timing jitter. An ultrafast demultiplexer based on a nonlinear optical loop mirror (NOLM) including a commercially available highly nonlinear fiber (HNLF) is employed to demultiplex data signal from 160 to 10 Gb/s. A back-to-back error-free demultiplexing experiment is carried out to verify the system performance.

Polarization mode dispersion (PMD) mitigation is performed using an optical 3R (re-amplification, re-shaping, re-timing) regenerator based on electro-absorption modulator (EAM) with wavelength conversion. System performance without and with 3R regeneration was separately studied by eye analysis and bit-error rate (BER) measurements. The signal quality was significantly improved by 3R regeneration under serious first order PMD (up to 40% of the bit interval) combined with second order PMD (up to about 520 ps2). The PMD mitigation margin of the proposed method is also investigated by measuring the sensitivity at BER 10^(-10). Further studies indicate that 3R regenerators have the potential to combat with the effects of PMD combined with polarization dependent loss (PDL) and polarization hole-burning (PHB).

An 8*10 Gb/s optical time-division-multiplexing (OTDM) system was demonstrated with an electroabsorption modulator (EAM) based short pulse generator followed by a two-stage nonlinear compression scheme which generated stable 10-GHz, 2-ps full-width at half-maximum (FWHM) pulse train, an opto-electronic oscillator (OEO) that extracted 10-GHz clock with a timing jitter of 300 fs from 80-Gb/s OTDM signal and a self cascaded EAM which produced a switching window of about 10 ps. A back-to-back error free demultiplexing experiment with a power penalty of 3.25 dB was carried out to verify the system performance.

In-line synchronous modulation as a way of mitigating the signal quality degradation induced by polarization mode dispersion (PMD) was experimentally studied using 10-Gb/s return to zero signal. Bit error rate of the degraded signal and the synchronously modulated signal under the differential group delay (DGD) values of 10, 20, 34, and 70 ps was measured and compared. The experimental results showed that in-line synchronous modulation is useful to mitigate the signal quality degeneration induced by PMD. 1-dB power penalty reduction was obtained even when the PMD was as high as 70% of the bit interval. The limitation of method is also discussed.

A Fabry-Perot (F-P) etalon and a semiconductor optical amplifier (SOA) were combined to preprocess the data signals before clock recovery. With this technology in the 10-Gb/s clock recovery utilizing injection mode-locked laser (IMLL) based on SOA, the amplitude fluctuation and timing jitters caused by the pattern effect in recovered clock pulses were greatly reduced, experimentally. It also demonstrated that clock could be recovered from the very degraded signals.

We experimentally demonstrate a novel multiwavelength continuous wave (CW) optical source with precise 25-GHz spacing based on the longitudinal mode-carving of a supercontinuum (SC) spectrum. The CW light was modulated with a 10-Gb/s non-return zero (NRZ) format. The experimental results show that the multiwavelength CW optical source is promising for dense wavelength division multiplexing (DWDM) systems.