The Experts below are selected from a list of 53520 Experts worldwide ranked by ideXlab platform

Masayuki Matsumoto - One of the best experts on this subject based on the ideXlab platform.

  • adaptive delay control for time interleaved multi channel amplitude limiter based on saturation of four wave mixing in a fiber
    Optics Express, 2011
    Co-Authors: Nor Shahida Mohd Shah, Masaru Sato, Masayuki Matsumoto
    Abstract:

    An adaptive delay control to maintain time-interleaving condition of multi-channel input Signals of all-optical amplitude limiter based on saturation of four-wave mixing (FWM) in a nonlinear fiber is demonstrated. The delay control utilizes as a Monitor Signal the optical power after the nonlinear fiber at a wavelength that is affected by interchannel FWM in the fiber. When the scheme is applied to 2 x 10 Gbit/s return-to-zero differential phase-shift keying Signals where the time separation between the input channels is intentionally changed randomly, the delay control works well and error free detection after transmission is obtained.

  • location optimization and distribution of polarization mode dispersion compensators using polarizers
    Journal of Lightwave Technology, 2004
    Co-Authors: Daniele Alzetta, Masayuki Matsumoto
    Abstract:

    This paper investigates the benefits of using compensators with either linear or elliptic variable polarizers in order to mitigate the effects of polarization-mode dispersion (PMD) in high-speed optical fiber transmission systems. Such compensators are characterized by only one or two degrees of freedom and the optical average power of the compensated Signal is used as a Monitor Signal, which simplifies the control algorithm. We maximize the tolerable differential group delay for the compensated system with two different approaches. In the first, we optimize the position of the compensator along the transmission line. In the second, we distribute a number of compensators through the transmission line. The attenuation of the optical Signal, caused by the use of polarizers in the PMD compensators, induces additional noise in amplified systems. We assess the impact of this impairment and show that the noise enhancement is limited in systems with erbium-doped fiber amplifiers operating in gain saturation.

Rongqing Hui - One of the best experts on this subject based on the ideXlab platform.

  • an adaptive first order polarization mode dispersion compensation system aided by polarization scrambling theory and demonstration
    Journal of Lightwave Technology, 2000
    Co-Authors: Hok Yong Pua, K V Peddanarappagari, Benyuan Zhu, C Allen, K Demarest, Rongqing Hui
    Abstract:

    An adaptive polarization-mode dispersion (PMD) compensation system has been developed to cancel the effects of first-order PMD by producing a complementary PMD vector in the receiver. Control parameters for the PMD compensation system comprised of a polarization controller and a PMD emulator are derived from the nonreturn-to-zero (NRZ) Signal in the channel to be compensated. Estimates of the link's differential group delay (DGD) and principal states of polarization (PSPs) based on this Signal are reliable when the Signal power is equally split between the link's two PSP's; however this condition cannot be assumed. To meet this requirement, we scramble the state of polarization (SOP) of the input Signal at a rate much greater than the response time of the PMD Monitor Signal so that each sample represents many different SOP alignments. This approach allows the effective cancellation of the first-order PMD effects within an optical fiber channel.

Daniele Alzetta - One of the best experts on this subject based on the ideXlab platform.

  • location optimization and distribution of polarization mode dispersion compensators using polarizers
    Journal of Lightwave Technology, 2004
    Co-Authors: Daniele Alzetta, Masayuki Matsumoto
    Abstract:

    This paper investigates the benefits of using compensators with either linear or elliptic variable polarizers in order to mitigate the effects of polarization-mode dispersion (PMD) in high-speed optical fiber transmission systems. Such compensators are characterized by only one or two degrees of freedom and the optical average power of the compensated Signal is used as a Monitor Signal, which simplifies the control algorithm. We maximize the tolerable differential group delay for the compensated system with two different approaches. In the first, we optimize the position of the compensator along the transmission line. In the second, we distribute a number of compensators through the transmission line. The attenuation of the optical Signal, caused by the use of polarizers in the PMD compensators, induces additional noise in amplified systems. We assess the impact of this impairment and show that the noise enhancement is limited in systems with erbium-doped fiber amplifiers operating in gain saturation.

Hok Yong Pua - One of the best experts on this subject based on the ideXlab platform.

  • an adaptive first order polarization mode dispersion compensation system aided by polarization scrambling theory and demonstration
    Journal of Lightwave Technology, 2000
    Co-Authors: Hok Yong Pua, K V Peddanarappagari, Benyuan Zhu, C Allen, K Demarest, Rongqing Hui
    Abstract:

    An adaptive polarization-mode dispersion (PMD) compensation system has been developed to cancel the effects of first-order PMD by producing a complementary PMD vector in the receiver. Control parameters for the PMD compensation system comprised of a polarization controller and a PMD emulator are derived from the nonreturn-to-zero (NRZ) Signal in the channel to be compensated. Estimates of the link's differential group delay (DGD) and principal states of polarization (PSPs) based on this Signal are reliable when the Signal power is equally split between the link's two PSP's; however this condition cannot be assumed. To meet this requirement, we scramble the state of polarization (SOP) of the input Signal at a rate much greater than the response time of the PMD Monitor Signal so that each sample represents many different SOP alignments. This approach allows the effective cancellation of the first-order PMD effects within an optical fiber channel.

Hirth Thomas - One of the best experts on this subject based on the ideXlab platform.

  • In-situ real-time Monitoring of spurious modes in HE$_{11}$ transmission lines using multi-hole couplers in miter bends
    EDP Sciences, 2020
    Co-Authors: Zach Alexander, Kasparek Walter, Lechte Carsten, Plaum Burkhard, Monaco Francesco, Schütz Harald, Stober Jörg, Idei Hiroshi, Hirth Thomas
    Abstract:

    Transmission of high-power millimeter waves for ECRH is often realised with oversized corrugated circular waveguides. Coupling from the gyrotron source to the waveguide is typically done via matching mirrors in free space. Small alignment errors of the system lead to the excitation of higher-order modes inside the waveguide beside the main transmission mode HE$_{11}$. Tose modes have comparably higher losses and can in worst case result in local fields exceeding the breakdown limit of the medium inside the waveguide. For alignment control over the whole pulse duration of the gyrotron, a set of hole-array couplers placed into a miter bend mirror probes the field inside the waveguide. The arrays are designed to detect the marker modes for beam offset and tilt (LP$^{(e=0)}$$_{11}$) as well as for beam waist mismatch (LP$_{02}$). In addition, a main mode coupler sensitive mostly for the HE$_{11}$ content is used as a power Monitor. By maximizing the Signal of the power Monitor and minimizing the content of marker modes, a first-order optimization of the coupling from free space to the waveguide can be achieved. Signal processing of the 140 GHz information is done at kHz range after downmixing, using a frequency shifted part of the power Monitor Signal. As the measurement system is placed in a miter bend mirror, it can also be easily installed at various locations along the transmission line to check for possible misalignments of the waveguide connections between miter bends. Simulation and low power experimental results will be shown

  • In-situ real-time Monitoring of spurious modes in HE11 transmission lines using multi-hole couplers in miter bends
    EDP Sciences, 2019
    Co-Authors: Zach Alexander, Kasparek Walter, Lechte Carsten, Plaum Burkhard, Monaco Francesco, Schütz Harald, Stober Jörg, Idei Hiroshi, Hirth Thomas
    Abstract:

    Transmission of high-power millimeter waves for ECRH is often realised with oversized corrugated circular waveguides. Coupling from the gyrotron source to the waveguide is typically done via matching mirrors in free space. Small alignment errors of the system lead to the excitation of higher-order modes inside the waveguide beside the main transmission mode HE11. Those modes have comparably higher losses and can in worst case result in local fields exceeding the breakdown limit of the medium inside the waveguide. For alignment control over the whole pulse duration of the gyrotron, a set of hole-array couplers placed into a miter bend mirror probes the field inside the waveguide. The arrays are designed to detect the marker modes for beam offset and tilt (LP(e=o)11 )as well as for beam waist mismatch (LP02). In addition, a main mode coupler sensitive mostly for the HE11 content is used as a power Monitor. By maximizing the Signal of the power Monitor and minimizing the content of marker modes, a first-order optimization of the coupling from free space to the waveguide can be achieved. Signal processing of the 140 GHz information is done at kHz range after downmixing, using a frequency shifted part of the power Monitor Signal. As the measurement system is placed in a miter bend mirror, it can also be easily installed at various locations along the transmission line to check for possible misalignments of the waveguide connections between miter bends. Simulation and low power experimental results will be shown