基于光纤环形腔激光器的可调谐全光波长转换器的研究

在光纤环形腔激光器中引入周期极化反转铌酸锂(PPLN)光波导，用该激光器产生的连续光作为抽运光和控制光，使其与外加的信号光发生非线性效应实现可调谐波长转换.介绍了基于准相位匹配的PPLN光波导中的和频与差频级联型全光波长转换器的基本原理.对抽运光、信号光、控制光以及转换光的光功率随着PPLN光波导的变化进行了模拟.还对转换效率随着转换光波长的变化进行了数值计算.实验验证了该波长转换器的可调谐性. 关键词： 周期极化反转铌酸锂 和频与差频 可调谐全光波长转换 光纤环形腔激光器     

准相位匹配级联二阶非线性全光波长转换研究

对基于级联和频差频非线性效应铌酸锂光波导新型全光波长转换器进行了理论研究。这种新型波长变换器需要两束抽运光源,它将输入的抽运光波长置于信号光波段窗口的两边,抽运光波长与信号光波长相近容易实现最佳耦合又不会占用信号波段,而且具有偏振不敏感的优点。从建立级联和频差频铌酸锂光波导全光波长转换器的理论模型出发,给出了波导中光相互作用的耦合模方程;利用逐步法详细推导了耦合模方程的解,得出了物理意义清晰的转换光功率表达式,分析了非线性晶体相互作用长度、抽运光功率对转换效率的影响,为级联和频差频铌酸锂光波导全光波长转换器优化设计提供了理论依据。     

周期性极化铌酸锂波导全光开关特性分析

从理论方面研究了基于和频与差频级联二阶非线性效应的周期性极化铌酸锂波导全光开关的特性,给出了耦合模方程在满足相位匹配条件下小信号近似的解析表达式.用数值方法求解耦合模方程,讨论了相位失配情况下输出的信号光功率与控制光功率的关系.分析了全光开关器件的极化反转光栅周期、晶体温度、控制光波长等参量的容差特性与相互作用长度和晶体温度的关系 关键词： 级联二阶非线性 光开关 准相位匹配 周期性极化铌酸锂     

周期域反转铌酸锂可调谐波长转换器的皮秒脉冲实验

实验研究了周期域反转铌酸锂光波导级联和频与差频二阶非线性效应(cSFG/DFG)皮秒脉冲间的可调谐波长转换。信号光采用重复频率为40 GHz,脉宽为1.57 ps的脉冲信号。当输入信号光和第一个控制光波长分别为1554.4 nm和1532.5 nm时,通过调节第二个控制光波长由1550.5 nm到1541.0 nm,输出信号光波长可从1536.0 nm调谐至1545.2 nm。当输入信号光波长改变时,通过改变第一个控制光波长以满足和频过程的准相位匹配条件,同时调节第二个控制光波长可以实现输出信号光波长的可调谐。实验中利用两个窄带可调谐滤波器有效抑制了掺铒光纤放大器引入的放大自发辐射噪声,同时观察到了波长下转换和波长上转换。     

基于PPLN波导中倍频与差频效应的全光波长转换

对准相位匹配的铌酸锂光波导中基于倍频与差频级联二阶非线性效应的全光波长转换进行了研究.在建立理论模型的基础上,分别对单脉冲以及序列光脉冲的波长转换过程进行了数值模拟,并对转换过程中的走离现象以及脉冲延迟进行了分析.模拟结果表明信号光与抽运光脉冲非同步输入的情况下可以克服走离效应的影响,得到更好的转换效率.另外,在抽运时钟脉冲的驱动下,输入的40 Gb/s的NRZ信号光可以转换为RZ转换光,且波形较好.     

单到单和单到双信道皮秒脉冲全光波长转换的实验研究

基于周期极化反转铌酸锂（PPLN）光波导级联倍频和差频（SHG+DFG）的二阶非线性效应,提出并实验研究了皮秒脉冲的可调谐波长转换以及单信道到双信道的波长转换.信号光采用重复频率为40 GHz,脉宽为1.57 ps的脉冲信号.连续抽运光由光纤环形腔激光器（FRL）提供.不同于传统的SHG+DFG型波长转换,信号光固定在PPLN光波导倍频过程的准相位匹配（QPM）波长处,通过调节抽运光的波长实现了转换空闲光的可调谐输出.当使用两个抽运光时实验观察到了单信道到双信道的波长转换.     

基于周期极化反转铌酸锂光波导高速非归零码到归零码的转换

研究了基于周期极化反转铌酸锂光波导级联二阶非线性效应实现非归零码到归零码高速全光码型转换的新方案,使用的是马赫-曾德尔干涉仪结构.转换原理是非归零码信号光在级联倍频和差频过程中受到的放大作用引起马赫-曾德尔干涉仪的不平衡,进而通过干涉相消产生归零码信号光输出.首先从耦合波方程出发,数值模拟了非归零码到归零码码型转换过程.然后分析了波导长度、光功率、相对时延对消光比的影响并对码型转换进行了优化设计.最后分析了转换带宽,模拟计算表明信号光在90nm的3dB带宽内可调谐,进而可以实现多信道的同时转换. 关键词： 码型转换 级联倍频和差频 周期极化反转铌酸锂 马赫-曾德尔干涉仪     

基于PPLN光波导和频与差频级联型全光波长转换的研究

介绍了基于准相位匹配周期极化反转铌酸锂光波导的和频与差频(SFG DFG)级联型全光波长转换技术的基本原理.计算了SFG DFG级联型波长转换的转换效率,分析了抽运光功率以及两个抽运光之间的间距对转换效率的影响,抽运光功率越大,转换效率越高;转换效率随着间距的增大先增大后减小.单抽运调节时的抽运带宽为0.5 nm,同时对信号光脉冲还有压缩作用,压缩比是0.68.     

铌酸锂光波导在超宽带信号产生中的新应用

铌酸锂光波导具有非线性系数大、响应速度快、低噪声等优点,因此在高速光信号处理中有着非常广泛的应用。铌酸锂光波导中有倍频、和频、差频、级联倍频和差频、级联和频与差频等二阶和级联二阶非线性效应,利用这些非线性效应可以实现多种高速全光信号处理功能。     

1.5μm波段基于级联二阶非线性的铌酸锂光波导全光波长变换的理论分析

研究了基于级联二阶非线性的铌酸锂波导全光波长变换器的特性.首先从耦合模方程出发,比较了数值分析结果与小信号近似分析的结果.其次在数值分析基础上,分析了铌酸锂晶体的温度变化导致相应基频光波波长与极化反转光栅周期的变化关系.最后分析了在不同相互作用长度下,转换的光波功率与有效基频光波波长带宽、温度调谐带宽、极化反转光栅周期带宽等关系,以对全光波长变换器件进行优化设计 关键词： 级联二阶非线性 波长变换 准位相匹配 铌酸锂光波导     

Double-ring cavity configuration of actively mode-locked multi-wavelength fiber laser with equally tunable wavelength spacing

A novel actively mode-locked multi-wavelength tunable fiber laser with equally increased or decreased wavelength spacing is presented. It is constructed using a double-ring cavity combined with an amplitude modulator and cascaded fiber Bragg gratings (FBGs). The cavity lengths for all FBGs are intrinsically identical due to the double-ring configuration, and simultaneous mode locking of multiple wavelengths is therefore achieved by applying only one mode-locking signal to the modulator. The FBGs are mounted on a organic plate with angles between adjacent gratings such that the forces applied to the FBGs have an equal force increment; thus, stretching or compressing the cascaded FBGs can achieve a wavelength tuning with equally increased or decreased wavelength spacing.This revised version was published online in March 2005. In the previous version, the published online date was missing     

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.     

All-optical NRZ-to-RZ format conversion with dual channel wavelength multicasting functions exploiting cross-phase modulation in a dispersion-flattened nonlinear photonic crystal fiber

All-optical single-to-dual channel format conversion from NRZ to RZ at 10 Gbit/s using cross phase modulation (XPM) in dispersion flattened highly nonlinear photonic crystal fiber (DF-HNL-PCF) is demonstrated. Format conversion with dual channels signal multicasting function is achieved by filtering simultaneously the blue- and red-chirped components of broadened optical spectrum induced by XPM between NRZ signal and clock light. Moreover, the wavelength tunability and dynamics characteristics of proposed format converter are also exploited experimentally by using NRZ signal light with different central wavelength and varying input power. Our results show that a wide wavelength operation range of 21.2 nm, extinction ratio (ER) and Q factor of over 10.9 dB and 6.1 are obtained. Furthermore, the influence of central wavelength offset of optical bandpass filter on converted RZ signal quality is investigated. The proposed scheme is simple, robust, and transparent to bit rate, which makes it very potential for application in future photonic networks.     

A Novel Method for Wavelength Conversion with Dual-pump Four-wave Mixing in a Semiconductor Optical Amplifier

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All-optical wavelength conversion and multicasting for polarization-multiplexed signal using angled pumps in a silicon waveguide

We report all-optical wavelength conversion and multicasting for a 20 Gb/s (2×10 Gb/s) polarization-multiplexed (Pol-MUX) nonreturn-to-zero amplitude-shift keying signal using four-wave mixing (FWM) in a silicon waveguide. The temporal waveforms and eye diagrams demodulated from both polarization channels of the converted idler are clearly observed. Moreover, the wavelength multicasting of the Pol-MUX signal is also demonstrated by using two incident pumps.     

Theoretical Study of SOA-Based Wavelength Conversion with NRZ and RZ Format at 40 Gb/s

We theoretically discuss 40 Gb/s semiconductor optical amplifier （SOA）-based wavelength conversion （WC） using a detuning optical bandpass Jilter based on ultrafast dynamic characteristics of SOA. Both the inverted and noninverted WCs are obtained by shifting the filter central wavelength with respect to the probe wavelength when input data signal is in return-to-zero （RZ） format. However, we can obtain format conversion from nonreturn- to-zero （NRZ） to pseudo-return-to-zero （PRZ） and inverted WC when the input signal is in NRZ format.     

The Study on the Performance of the Wavelength Conversion Based on a Tunable External Cavity Semiconductor Laser

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The Study on the Performance of the Wavelength Conversion Based on a Tunable External Cavity Semiconductor Laser

In this paper, the performance of the wavelength conversion based on a tunable external cavity semiconductor laser (ECL) was studied. The static wavelength conversion was achieved in the tunable wavelength range of the ECL. The dynamic wavelength conversions of 155 Mb/s and 622 Mb/s nonreturn to zero (NRZ) signals were realized. The simulation of the ECL output characteristics using modified compound cavity rate equation shows that the higher bit rate wavelength conversion can be realized by increasing the relaxation oscillation frequency of the ECL. When the modulated bit rate is much lower than the relaxation oscillation frequency, under a fixed input signal power, there is an optimal bias current for the wavelength converter based on ECL.