双泵浦两段高非线性光纤级联的光纤参量放大器

提出和设计了一种宽带宽、高增益和增益平坦的光纤参量放大器,它具有双泵浦和两段高非线性光纤级联的结构.选择光纤的四阶色散系数作为优化的指标之一,用普通的数组循环计算法,对双泵浦及两根高非线性光纤组成的系统进行模拟,获得了峰值增益62.46 dB,起伏小于5 dB,带宽高达424nm的光纤参量放大器.     

光纤参量放大器的最新进展

从单抽运和双抽运光纤参量放大器两种结构展开论述,着重介绍了光纤参量放大器对信号的放大能力及双抽运光纤参量放大器作为波分复用或密集波分复用系统放大器的可能性和所面临的问题,表明具有高增益和宽带宽的光纤参量放大器有可能成为新一代的光放大器.最后介绍了波长转换器方面的最新进展及双抽运偏振态相互正交时的光纤参量放大器在波长转换方面的独特性能.     

Multiwavelength Fiber Optical Parametric Oscillator

We demonstrate, for the first time to the best of our knowledge, a multiwavelength fiber ring laser using a continuous-wave dual-pump fiber optical parametric amplifier (FOPA) as gain medium. In the ring cavity, two high-power pumps are injected into a spool of 1-km highly nonlinear dispersion-shifted fiber to generate the parametric gain, and a superimposed chirped fiber Bragg grating is used as the comb-like filter. Benefiting from the high and flat gain of the dual-pump FOPA, seven lasing lines around 1.55 mum with wavelength spacing of 1 nm have been obtained. Each lasing line has a linewidth of as narrow as 20 pm and an extinction ratio of > 30 dB. The proposed mechanism using a dual-pump FOPA as gain medium is a promising alternative for generating multiwavelength laser.     

Polarization-insensitive fiber optical parametric amplifier based on polarization diversity technique with dual parallel pumps

By analyzing the principle of dual-pump parametric amplification and the polarization dependent gain of fiber optical parametric amplifier(FOPA),a polarization-insensitive FOPA based on polarization-diversity technique with dual parallel pumps is presented.The performances of polarization-insensitivity,gain and BER are theoretically analyzed and numerically simulated by comparing the proposed scheme with parallel pump solution and orthogonal pump solution.The presented solution can reduce the complexity of state of polarization(SoP) of pumps.     

光纤参量放大器增益特性的理论与仿真分析

为了优化光纤参量放大器的增益特性,利用理论分析,对FOPA在不同光纤长度、不同泵浦光功率及不同光纤非线性系数下的增益与带宽特性进行了比较与分析。结果表明:使用较长的高非线性光纤、较大的泵浦光、或较大的非线性系数,均可提高FOPA的增益,增益带宽也可随着泵浦光功率和非线性系数的增大而增大。此外,利用仿真模拟对理论分析结果进行了验证。虽然,仿真结果与理论分析结果间略有偏差,但仿真结果依然较好的验证了理论结果的正确性与可行性。     

Influence of Raman effect on the noise characteristics in a dual pump FOPA

Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier (FOPA) is investigated. Taking the Raman effect into account, the modified coupled amplitude equations are firstly built, then the influences of Raman effect on the stokes and anti-stokes wavelengths with different initial signal powers are further analyzed. Besides, the effect on the FOPA gain is also shown with the same initial signal power and constant noise figure (NF).     

具有高阶色散双抽运级联光纤参量放大器的增益

利用一组耦合方程,在理论上推导出了双抽运、三段光纤级联结构的参量放大器的增益表达式。研究表明在双抽运情况下,光纤参量放大器(FOPA)的增益随光纤长度、抽运光功率的增加而变大;同时,增益的大小和平坦性能也受到光纤色散特性的影响,从反常色散区到正常色散区,增益带宽逐渐变小,增益不平坦性有一定的改善;在二阶色散系数不变的情况下,光纤参量放大器增益带宽随四阶色散数的增加而减小。采用多段光纤级联结构,可以均衡光纤参量放大器增益的不平坦性。     

Noise characteristics of fiber optical parametric amplifiers

We derive an analytical theory for the noise figure of an undepleted and lossless fiber optical parametric amplifier (FOPA). Both the signal and the wavelength converted idler are investigated. Our theory is applicable for both an ideal pump power source, as well as a noisy one. We find that a noisy pump source can severely degrade the performance at high gain due to the stochastic gain-variations the signal and idler will experience. The theory is compared with Monte Carlo simulations of the FOPA and an excellent agreement is obtained. Simulations in the gain-depleted region show the possibility to reach below quantum-limited, phase-insensitive amplification for single channel transmission.     

Gain and Bandwidth Characterization in Fiber Optical Parametric Amplifiers

The fiber optical parametric amplifier (FOPA) is characterized using a optical time-domain reflectometer-based technique. The measurement technique visualizes how the parametric gain and bandwidth evolves as a function of length. Both gain and bandwidth are measured and compared to theory and a good agreement is found between them, making this technique useful for characterization of FOPAs. The impact of zero dispersion wavelength variations in the fiber and polarization dependence of the measurement technique are also discussed     

Theoretical demonstration for signal gain in multiple four-wave mixing processes based on cubic susceptibility medium

An insight into the signal gain in multiple four-wave mixing (MFWM) processes based on a cubic susceptibility medium is theoretically proposed and demonstrated. A dual-pumped fiber optical parametric amplification (FOPA) model is developed with the exact expressions for the signal gain and its 3-dB bandwidth successfully yielded. With these analytical expressions, we show that when pump-1 and pump-2 wavelengths tuned at 1549 and 1551.02nm, the 3-dB bandwidth of the signal gain can be achieved at about 2253.4nm theoretically by properly setting the pumped powers. Numerical simulations show that there is a small pinnacle emerging in the signal gain spectrum owing to the degenerate OPA process occurring. The proposed OPA model can find potential applications in all-optical wavelength conversion, optical amplifier, and all-optical sampling.     

Amplitude Regeneration of RZ-DPSK Signals in Single-Pump Fiber-Optic Parametric Amplifiers

The input power tolerance of a single-pump fiber-optic parametric amplifier (FOPA) is experimentally shown to be enhanced for return-to-zero differential phase-shift keying (RZ-DPSK) modulation compared to RZ on–off keying modulation at 40 Gb/s. The improved nonlinear tolerance is exploited to demonstrate amplitude regeneration of a distorted RZ-DPSK signal in a gain-saturated FOPA. An optical signal-to-noise ratio penalty of 3.5 dB after amplitude distortion is shown to be reduced to 0.2 dB after the FOPA, thus clearly demonstrating the regenerative nature of saturated FOPAs for RZ-DPSK modulation.      

Noise characteristics of dual-pump fiber-optic parametric amplifiers

The noise figure (NF) properties of an undepleted and lossless dual-pump fiber-optic parametric amplifier (FOPA) are theoretically and numerically investigated. The theoretical study takes into account the noise characteristics of the two pump waves that are considered to have parallel polarization states for gain maximization. It is shown that noisy pump waves degrade the amplifier's NF, especially when the amplifier is operating at high gain values and when the input signal is high. The theoretical observations are validated by Monte Carlo numerical simulations, and the agreement between them is excellent. Finally, a comparative study concerning the noise characteristics of dual-pump and single-pump FOPAs is performed.     

Fiber optical parametric amplifier pulse source: theory and experiments

An evaluation of a fiber optical parametric amplifier (FOPA)-based pulse source in terms of pulse width and chirp is presented. Experiments are performed when operating the FOPA as a pulse source, requiring a sinusoidally modulated pump. The FOPA is generating pulses at 10 GHz, and are measured using a streak camera capable of measuring pulses as a function of time, wavelength, and intensity. Experimental results are presented together with a theory for chirp and pulse widths that show good agreement.     

Design of fiber-optical parametric amplifiers by genetic algorithm

Genetic algorithm is adopted to give an automatic design scheme for fiber-based optical parametric amplifiers (FOPAs). Main steps of the optimization process and discussion about this algorithm are presented. The results show that present FOPA has more than 300-nm flat bandwidth with a central wavelength of 1500 nm and a gain ripple of less than 0.3 dB. Meanwhile, fluctuation in zero-dispersion wavelength of fibers is taken into consideration and its influence is briefly analyzed.     

Improved performance of polymer photodetectors using indium–tin-oxide modified by phosphonic acid-based self-assembled monolayer treatment

For organic photodetectors (OPDs), in order to realize high incident-photon-to-current conversion efficiency (IPCE) and high on/off ratio, the characteristics of hole-only devices and polymer photodetectors with indium–tin-oxide (ITO) modified by phosphonic acid-based self-assembled monolayer treatment in a short time are investigated. 1H,1H,2H,2H-Perfluorooctanephosphonic acid (FOPA) treatment results not only in lowering of the injection barrier at the ITO/organic layer interface but also in the lowering of the contact resistance between ITO and the organic layer. An OPD based on a blend of a donor, poly(9,9-dioctylfluorene-co-bithiophene) (F8T2), and an acceptor, fullerene derivative [6-6]phenyl-C61-butyric acid methyl ester (PCBM) with FOPA treatment exhibits blue-light sensitivity and IPCE of approximately 75% at −4 V. For the F8T2:PCBM device with FOPA, the IPCE is improved, and the dark current hardly increases. F8T2:PCBM device with FOPA treatment exhibits high on/off ratio, wide detector dynamic range and cut-off frequency of more than 10 MHz under reverse voltage.     

Fiber-optic parametric amplifier in a loop mirror configuration

A configuration of the fiber-optic parametric amplifier (FOPA) using an optical loop mirror is presented and evaluated. Previously presented setups usually suffer a 10-dB loss on the input for the signal wavelength. The setup presented in this letter allows, in principle, virtually lossless combination and separation of pump and signal. In addition, over 30-dB suppression of the pump was achieved in this configuration. Bit-error-rate measurements using the FOPA as preamplifier were compared to a thermal limited receiver. The receiver sensitivity for the FOPA was -30 dBm, which was 10 dB better than the thermally limited receiver.     

基于光纤光参量放大的多通道全光非归零/归零码转换器

提出了一种基于光纤光参量放大器(FOPA)的多通道全光非归零码(NRZ)/归零码(RZ)调制格式转换的方案.该方案中,非归零码信号与同步的时钟抽运光共同注入到高非线性光纤(HNLF)中,由高非线性光纤构成的参量放大器把非归零码信号转换为归零码信号,同时不改变信号光的波长.多通道的码型转换器以两路10 Gb/s的非归零码进行了实验论证.转换后的归零码信号的信噪比(SNR)高于7.6 dB,其脉冲宽度约为30 ps,并且具有3dB的消光比(ER)提高.根据多通道码型转换器的实现原理,该码型转换器可以应用于40 Gb/s或更高比特率的多通道码型变换操作.     

利用光纤参量放大器构成全光与门

利用光纤参量放大器(FOPA)中的波长转换特性完成全光与逻辑运算。以波长转换的原理为基础, 从两路输入光波的四种码字组合的相位匹配关系入手, 证明了FOPA的闲散光输出与两路输入光波的逻辑关系符合与门的逻辑。通过龙格-库塔方法数值求解非线性耦合方程组, 仿真证实了FOPA的输出与输入光波满足全光与门的逻辑, 研究了此全光与逻辑门闲散光波的输出功率随光纤长度、输入光波的功率比值以及输入光波波长位置的变化关系, 为实际中优化设计全光与门提供了参考。并对100 Gb/s的全光与逻辑运算中所应选择的输入光波脉冲宽度的问题进行了讨论。     

光纤参量放大技术及应用

光纤参量放大基于在技术上的优势,越来越引起研究人员的重视.文章介绍了光纤参量放大器的结构及近期的研究情况,概述了其在分立集总放大、波长透明转换、慢光的产生,归零码生成及光时分复用(OTDM)等方面的应用.     

常规DSF光纤参变放大器的带宽拓宽研究

为了拓宽常规色散位移光纤(DSF)型双抽运光纤参变放大器(FOPA)的放大带宽,提出了用DSF和单模光纤(SMF)级联来构造周期色散补偿双抽运FOPA的思想。利用SMF正的二阶色散以减小DSF负的四阶色散引起的相位失配,从而达到有效拓宽FOPA放大带宽的目的。结合四波混频耦合方程对该双抽运FOPA进行仿真研究,得到拓宽为69nm的放大带宽的结果。结果表明,光纤长度一定时,采用给出的最佳补偿光纤长度进行色散补偿,可有效减小因DSF四阶色散引起的相位偏移,进而拓宽放大带宽;分多段级联进行色散补偿时,可进一步拓展放大带宽。