新型全光逻辑与门的理论和实验研究

提出一种基于级联单端半导体光放大器（SOA）中交叉增益调制效应的新型全光逻辑与门， 建立了该方案的理论模型，数值模拟和实验实现了10Gb/s的全光逻辑与运算功能，分析了逻辑与运算结果与输入信号功率和消光比之间的关系，理论分析结果与实验结果相符合. 关键词： 半导体光放大器 交叉增益调制 全光逻辑与门     

基于半导体光放大器四波混频效应的多种调制格式的波长转换实验

实验报道了利用半导体光放大器(SOA)的四波混频(FWM)效应实现多种码型的波长转换.其中对于非归零(NRZ)信号实现了从单信道到三信道的多波长转换.调制速率从10 Gb/s到40 Gb/s均实现多波长转换.对于归零(RZ)信号分别实现了20 Gb/s和40 Gb/s的RZ格式的波长转换和40 Gb/s的载波抑制归零(CSRZ)格式的波长转换,利用光纤布拉格光栅(FBG)作为带陷滤波器消除共轭光和抽运光之间的串扰.对于非归零差分相移键控(NRZ_DPSK)信号分别实现了20 Gb/s和40 Gb/s的波长转换,利用实验室自制的光纤延时干涉仪进行NRZ-DPSK信号的解调.基于FWM效应的转换光的输出消光比大于7 dB,转换后消光比退化约为3 dB.     

High-Order Ultrawideband Pulse Generation from NRZ-DPSK Signals

A simple method to generate ultrawideband （UWB） doublet and triplet from nonreturn-to-zero （NRZ） differential phase shift keying （DPSK） signals is proposed and experimentally demonstrated. The proposed configuration consists of a Mach-Zehnder modulator （MZM） to generate NRZ-DPSK signals, a section of single-mode fibre to form a microwave bandpass filter, which is used to generate doublet pulses, and a Gaussian optical bandpass filter （OBF）, which serves as a frequency discriminator to generate higher-order UWB pulses. A pair of polarity- reversed triplet pulses is achieved by locating the optical carrier at the positive and negative linear Mopes of the OBF, where the OBF detuning is 0.12nm and -0.2 nm, respectively. The spectra of the pair of UWB triplets have a central frequency of 5 GHz and 5.6 GHz, and have a -10 dB bandwidth of 6.9 GHz and 8.1 GHz, respectively. The UWB pulses remain doublet shape when the light wavelength is located at the peak of the OBF. The spectrum of the doublet has a central frequency of 5.6 GHz and a -10 dB bandwidth of 6.9 GHz.     

Microwave photonic filter with a continuously tunable central frequency using an SOI high-Q microdisk resonator

Utilizing a high-Q microdisk resonator(MDR) on a single silicon-on-insulator(SOI) chip, a compact microwave photonic filter(MPF) with a continuously tunable central frequency is proposed and experimentally demonstrated. Assisted by the optical single side-band(OSSB) modulation, the optical frequency response of the MDR is mapped to the microwave frequency response to form an MPF with a continuously tunable central frequency and a narrow 3-dB bandwidth. In the experiment, using an MDR with a compact size of 20×20 μm2and a high Q factor of 1.07×105, we obtain a compact MPF with a high rejection ratio of about 40 dB, a 3-dB bandwidth of about 2 GHz, and a frequency tuning range larger than12 GHz. Our approach may allow the implementation of very compact, low-cost, low-consumption, and integrated notch MPF in a silicon chip.     

基于半导体光放大器和光学滤波器的同相波长转换理论研究

采用半导体光放大器(SOA)级联滤波器的方案可以实现高速全光波长转换,其中,滤波器实质上是对SOA输出信号的光谱进行优化操作.文中利用带通滤波器(BPF)和延时干涉仪(DI)组成的光谱优化器,不仅实现了80Gbit/s同相波长转换,而且基于遗传算法设计光谱优化器的参数,极大地提高了输出信号的质量.同时,也从理论上分析了SOA中超快带内效应对信号光谱的影响以及光谱优化器中BPF和DI的消光比对输出信号质量的影响.