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The impact of fiber polarization mode dispersion (PMD) on the bit error rate (BER) performance of a direct sequence optical code-division multiple-access system is analyzed by the split-step Fourier method based on the coupled nonlinear Schrödinger equation, the three-dimensional Poincare sphere theory and the Jones matrix method. When the incident pulse's width is bigness than the chip duration, which causes spreading and overlapping of chips and degrades system performance due to increased interchip interference and reduced received optical power conduce cannot decoding or error decoding. When the incident pulse's width is less than the chip duration, good encoding/decoding performance can be achieved. 相似文献
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We analyzed the effect of PMD on RZ format signal transmission with and without the use of FEC. The results indicate that FEC can partially improve the system BER performance, but with limited effectiveness for large average DGD values. 相似文献
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为了研究非线性相位噪声对差分正交相移键控(DQPSK)调制系统性能的影响,在理论推导非线性相位噪声数学模型的基础上,通过固定接收端信噪比不变,仿真分析了40Gb/s速率时DQPSK调制系统误码率随输入信噪比的变化情况。结果表明:与二进制差分相移键控(DPSK)调制相比,DQPSK调制对非线性相位噪声的影响更为敏感,当非线性效应较大时,非线性相位噪声将使系统误码率显著增大,严重影响系统通信质量。因此,当采用DQPSK调制时,必须考虑非线性相位噪声对系统性能的影响。 相似文献
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The paper proposes an OCDM/WDM PON system solution based on DQPSK which has passed theoretical and simulative tests. This solution can realize the effective integration between OCDMA technology and DWDM system. Compared with the traditional OCDMA/WDM system, this solution saves a large number of OCDMA decoders/encoders, effectively reduces the complexity of the system integration process, and accomplishes seamless integration and upgrade. The results show that compared with the OCDM/WDM PON system based on OOK, the OCDM/WDM PON system based on DQPSK has advantages as follows: higher sensitivity for the receiving system; better system security and wider system noise margin. These advantages provide the DQPSK-based OCDM/WDM PON system solution with a better application prospect. 相似文献
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In this paper, we evaluate the performance of 40 Gb/s duobianry optical transmitter for different scattering section dispersion and polarization-mode dispersion coefficient of single mode fiber. We observe that the variable scattering section dispersion considerably improves the performance of duobinary optical system as compared to fixed scattering section dispersion where the Q value fluctuates over wide frequency range. Also, duobinary system observes pulse delay of 7 ps for the fixed scattering section dispersion while there is no delay in the received output signal if variable scattering section dispersion is considered. 相似文献
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This paper mainly studies the combination of quadrature modulation of the phase modulation/amplitude modulation. Phase domain modulation formats mainly study the differential quadrature differential phase shift keying (DQPSK) and amplitude domain modulation format mainly studies the on–off keying (OOK). Through the above analysis, we know orthogonal to modulation technology of OCDMA system solution-PON DQPSK/OOK based on has a large advantage over the ordinary PON system. 相似文献
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通常情况下,评价光学成像系统像质的几个重要参数,如能量集中度(Strehl比)、分辨率、焦深等,都是以标量衍射理论为基础进行计算和分析的.考虑光波的矢量偏振特性,尤其是在高数值孔径系统中,标量衍射的精度已不能满足精度要求.本文讨论了在采用矢量衍射计算方法基础上,上述成像参数的变化,所讨论系统入瞳面各点为偏振方向一致的线偏光或部分偏光,以便于考察偏振对所述成像参数的影响,通过公式推导和数值计算,得出了由于偏振的影响.系统衍射斑能量极大值变小,像面和偏振平行方向分辨率降低,分辨率出现各向异性,只有系统焦深受偏振影响较小.而这些矢量效应会随着系统数值孔径的提高而愈加明显,因此在分析处理数值孔径较高的光学系统时必须使用矢量衍射方法.最后讨论了轴外点衍射斑的计算. 相似文献
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We propose a novel modulation format of 50% RZ polarization interleaved multiplexing DQPSK for high-speed self-homodyne receiving systems. The proposed modulation format enables excellent tolerance of chromatic dispersion and polarization crosstalk. In self-homodyne receiving systems, the proposed format can reduce the cost of adaptive equalization module. It has potential applications in long-reach self-homodyne optical communication systems. 相似文献
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提出利用变焦系统设计思想来快速实现复杂航空相机光学系统消热差设计的新方法,基于光学式补偿基础,建立了变焦设计与消热差设计的对应关系模型。设计常温下满足成像质量要求的消色差的良好光学系统;建立多个变焦位置,分别对应于不同的工作温度状态;通过优化设计快速发现材料组合,满足宽工作温度范围内像质均良好的要求。利用该方法设计了一工作于0.45~0.70 m波段,焦距650 mm,F数为5.6,视场为5.5的航空CCD相机光学系统,结果表明系统在-40~60 ℃之间成像均保持良好,调制传递函数下降5%。 相似文献
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An optical transfer matrix (OTM) is introduced and proposed to analyze the performance of optical polarization imaging systems. This 4 × 4 OTM describes the frequency transfer characteristics of the optical system for each Stokes parameter. It includes the transfer functions and the crosstalk functions. The transfer functions can be used to analyze the imaging quality of the system for each polarization component, while crosstalk functions indicate the polarization errors. We calculate the modulation transfer matrix as an example and numerically simulate the Stokes vector imaging for a polarization imaging system with a singlet and rotating polarization elements. The simulated imaging results show conformance with the analysis. 相似文献
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提出利用变焦系统设计思想来快速实现复杂航空相机光学系统消热差设计的新方法,基于光学式补偿基础,建立了变焦设计与消热差设计的对应关系模型。设计常温下满足成像质量要求的消色差的良好光学系统;建立多个变焦位置,分别对应于不同的工作温度状态;通过优化设计快速发现材料组合,满足宽工作温度范围内像质均良好的要求。利用该方法设计了一工作于0.45~0.70 m波段,焦距650 mm,F数为5.6,视场为5.5的航空CCD相机光学系统,结果表明系统在-40~60 ℃之间成像均保持良好,调制传递函数下降5%。 相似文献
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PMD对不同线路码型高速光纤通信系统影响的研究 总被引:4,自引:0,他引:4
研究了在采用NRZ码、电RZ码、光RZ码及CSRZ码四种不同的线路码型并在接收机不同光滤波器带宽下,研究了偏振模色散(PMD)对40Gbit/s单波道光纤通信系统产生的不可用概率。 相似文献
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We characterize theoretically and experimentally the degradation of polarization entanglement in a fiber-optic entanglement distribution system where one of the optical fibers is exposed to the effects of polarization mode dispersion (PMD). We show gradual reduction of entanglement with increasing PMD and find that the highest PMD tolerance is achieved when the bandwidth of the pump used to generate the entangled photons in a χ((3)) process is approximately half the bandwidth of the quantum channels. 相似文献
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为了实现NA1.35投影光刻光学系统高质量成像,在设计过程中除了控制波像差,还需进一步优化光学系统的偏振像差。利用Jones光瞳和物理光瞳表达了NA1.35投影光刻光学系统的偏振像差,并用二向衰减量与延迟量分析了光学系统偏振像差的大小;根据光线入射到不同光学面上最大入射角度的不同,为每个光学面设计相应的膜系以优化光学系统的偏振像差。相比于采用常规膜系,膜系优化后NA1.35投影光刻光学系统的二向衰减量和延迟量分别减小到了0.021 8、0.057 2 rad,即减小了光学系统的偏振像差。利用Prolith光刻仿真软件,分别对采用常规膜系和优化膜系的NA1.35投影光刻光学系统进行曝光性能仿真,结果显示:膜系优化后光学系统的成像对比度提高了4.4%,证明了NA1.35投影光刻光学系统偏振像差优化方法的有效性。 相似文献
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The effect of coherence properties of illumination on image resolution, well known in a scalar case, is studied for the case of vector electromagnetic illumination. Using an example of vector Gaussian Schell-model illumination, we analyze the dependence of optical system resolution on the transverse correlation lengths of the orthogonal field components and on the ratio of the powers of these components, each taken separately. 相似文献
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Md. Nur-Al-Safa Bhuiyan Motoharu Matsuura Hung Nguyen Tan Naoto Kishi 《Optical Review》2014,21(1):48-53
Transmission characteristics of polarization shift keying (PolSK) signal is experimentally demonstrated in this work. Performance degradation due to transmission is improved using optical phase conjugation (OPC) technique. The wavelength converter based on the proposed state of polarization (SOP) transparent scheme for PolSK signal is effective to use it as mid-link optical phase conjugator and which is difficult to achieve using conventional wavelength conversion scheme. It is found that for fiber transmission, the performance of both of the orthogonal SOPs of the PolSK signal is different for their respective chirping characteristics which can be optimized to be similar using proposed OPC technique. 相似文献