Sampling Function

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Hongpu Li - One of the best experts on this subject based on the ideXlab platform.

  • DC-Sampled Helical Fiber Grating and its Application to Multi-Channel OAM Generator
    IEEE Photonics Technology Letters, 2019
    Co-Authors: Peng Wang, Hua Zhao, Ryo Mizushima, Shoma Ishikami, Hongpu Li
    Abstract:

    A novel DC-Sampling method allowing generation of a multichannel helical long-period fiber grating (HLPG) has been proposed. Unlike the previous phase-only Sampling method where phases of the continuous Sampling Function must be discretely adopted and inserted into the local pitches of the grating (thus high precision setups for controlling all the individual pitches of the grating are essential), the proposed method can greatly facilitate the fabrication of the multichannel HLPG by using the CO2 laser writing technique. As one typical example, the DC-sampled 3-channel HLPG has been demonstrated both theoretically and experimentally. The orbital angular momentum (OAM) modes inherently existed in this kind of HLPGs have also been verified. This is the first report for generation of a multi-channel (wavelength) OAM mode by using only one HLPG.

  • Multichannel Long-Period Fiber Grating Realized by Using the Helical Sampling Approach
    Journal of Lightwave Technology, 2019
    Co-Authors: Shoma Ishikami, Hua Zhao, Hongpu Li
    Abstract:

    A simple and efficient Sampling approach enabling fabrication of a multichannel long-period fiber grating (LPG) was proposed and demonstrated for the first time both theoretically and experimentally. Unlike the previous Sampling methods in which a Sampling Function is employed to modulate only the amplitude of the seed grating, i.e., the ac part of the grating's index-modulation, in this study, a helical-type Sampling is used to modulate only the dc part of the grating's index-modulation. The proposed method enables a significant enhancement in the utilization efficiency of the fiber, and it will greatly facilitate the fabrication of multichannel LPG by using the CO2 laser technique. As one typical example, a helically sampled three-channel LPG was successfully demonstrated both numerically and experimentally, and it was found that the experimental results agree well with the theoretical predictions.

  • reflection equalization of the simultaneous dispersion and dispersion slope compensator based on a phase only sampled fiber bragg grating
    Optics Express, 2008
    Co-Authors: Ming Li, Hongpu Li
    Abstract:

    A novel approach for the reflection equalization of a phase-only sampled fiber Bragg grating (FBG) is presented, where the grating is specially designed as a simultaneous dispersion and dispersion-slope compensator with channels up to 51. The Sampling-Function used is given with an analytical form with a linearly-chirped Sampling period and is optimized by using the simulated annealing algorithm.

  • Optimization of a continuous phase-only Sampling for 81-channel fiber Bragg gratings
    2006 Digest of the LEOS Summer Topical Meetings, 2006
    Co-Authors: Hongpu Li, Ming Li, K. Ogusu, Yunlong Sheng, J.e. Rothenberg
    Abstract:

    In this paper, a novel continuous phase-only Sampling Function is introduced, in which optimization for an 81-channel phase-only Sampling Function with excellent channel uniformity and high in-band energy efficiency is obtained by using the simulated annealing algorithm. Compared to the numerical results, an 81-channel (spacing 50 GHz) phase-only sampled linearly chirped FBG are successfully demonstrated

  • Split of phase shifts in a phase mask for fiber Bragg gratings
    IEEE Photonics Technology Letters, 2004
    Co-Authors: Y. Sheng, Hongpu Li, J.e. Rothenberg, Ying Wang, J. Zweiback
    Abstract:

    Using rigorous finite-difference in time-domain analysis for near field diffraction of a phase-shifted phase mask, we discover that the phase shift is not replicated in the fiber by side-writing through the mask, but is split into two half-magnitude phase shifts with a separation proportional to the fiber-to-phase mask spacing. We show by a physical model for cumulated phase that spectral asymmetry observed in a multichannel fiber Bragg grating (FBG) with a binary phase Dammann Sampling Function is caused by this split. We propose a new binary phase-only Sampling design, which precompensates the phase-shift splitting effect and produces high channel count FBGs without asymmetry in the channel spectrum.

Jing Wang - One of the best experts on this subject based on the ideXlab platform.

  • LCN - S3: Smart selection of Sampling Function for passive network measurement
    2011 IEEE 36th Conference on Local Computer Networks, 2011
    Co-Authors: Xingyu Ma, Chengchen Hu, Junchen Jiang, Jing Wang
    Abstract:

    Flow size statistics is a fundamental task of passive measurement. In order to bound the estimation error of passive measurement for both small and large flows, previous probabilistic counter updating algorithms used linear or nonlinear Sampling Function to automatically adjust the Sampling rate. However, each of these methods employed a pre-set and fixed Sampling Function during the measurement period. As a result, the performance would vary for different flow distributions. In this paper, we propose a Smart Selection Sampling (S3) approach, which can tune the Sampling Function to reach a comparatively lower relative error. The key component of S3 is a heuristic algorithm leveraging the flow distribution information to determine a better Sampling Function so as to achieve better measurement accuracy. Experiments under real trace and synthetic traces demonstrate that S3 is more accurate than the previous work if given the same memory sizes to accommodate flow statistics counters.

  • S3: Smart selection of Sampling Function for passive network measurement
    2011 IEEE 36th Conference on Local Computer Networks, 2011
    Co-Authors: Chengchen Hu, Junchen Jiang, Jing Wang
    Abstract:

    Flow size statistics is a fundamental task of passive measurement. In order to bound the estimation error of passive measurement for both small and large flows, previous probabilistic counter updating algorithms used linear or nonlinear Sampling Function to automatically adjust the Sampling rate. However, each of these methods employed a pre-set and fixed Sampling Function during the measurement period. As a result, the performance would vary for different flow distributions. In this paper, we propose a Smart Selection Sampling (S3) approach, which can tune the Sampling Function to reach a comparatively lower relative error. The key component of S3 is a heuristic algorithm leveraging the flow distribution information to determine a better Sampling Function so as to achieve better measurement accuracy. Experiments under real trace and synthetic traces demonstrate that S3 is more accurate than the previous work if given the same memory sizes to accommodate flow statistics counters.

Jia Feng - One of the best experts on this subject based on the ideXlab platform.

G.p. Agrawal - One of the best experts on this subject based on the ideXlab platform.

Ming Li - One of the best experts on this subject based on the ideXlab platform.

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