Optical phase-locked loop for coherent transmission over 500km using heterodyne detection with fiber lasers

Keisuke Kasai; Jumpei Hongo; Masato Yoshida; Masataka Nakazawa

doi:10.1587/elex.4.77

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Optical phase-locked loop for coherent transmission over 500km using heterodyne detection with fiber lasers

Keisuke Kasai, Jumpei Hongo, Masato Yoshida, Masataka Nakazawa

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Keywords: optical phase-locked loop, coherent transmission, fiber laser, frequency stabilization

JOURNAL FREE ACCESS

2007 Volume 4 Issue 3 Pages 77-81

DOI https://doi.org/10.1587/elex.4.77

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Abstract

We have developed an optical phase-locked loop (OPLL) that can operate over 500km. The coherent transmitter is a 1.54µm ¹³C₂H₂ frequency-stabilized CW fiber ring laser with a frequency stability of 2.0 × 10^-11 and a linewidth of 4kHz. To obtain wide band operation with a bandwidth of 1GHz, we fabricated a high-speed fiber laser as a local oscillator. By using these fiber lasers, the OPLL circuit successfully generated an intermediate frequency signal with a phase error variance of 7.9 × 10^-3 rad.

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