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Fiber Link Stabilization with a Multicore Fiber Amplifier

Yifan Liu, Takuma Nakamura, Daniel J. Elson, Yuta Wakayama, Charles A. McLemore, Tetsuya Hayashi, Mikael Mazur, Nicolas Fontaine, Franklyn Quinlan, Nazanin Hoghooghi

Abstract

We study the use of separate cores of a multicore erbium-doped fiber amplifier (MC-EDFA) in a noise-canceled link for ultrastable optical frequency transfer. We demonstrate fractional frequency instability of $5\times10^{-19}$ at 1000 s averaging time for the stabilized MC-EDFA alone and $1.4\times10^{-18}$ at 1000 s averaging time when integrated with a 40 km-long 7-core spooled fiber. This study further establishes multicore fiber (MCF) networks as a promising platform for ultrastable frequency transfer, serving as an important step toward incorporating precision time and frequency distribution into future MCF communication infrastructures.

Fiber Link Stabilization with a Multicore Fiber Amplifier

Abstract

We study the use of separate cores of a multicore erbium-doped fiber amplifier (MC-EDFA) in a noise-canceled link for ultrastable optical frequency transfer. We demonstrate fractional frequency instability of at 1000 s averaging time for the stabilized MC-EDFA alone and at 1000 s averaging time when integrated with a 40 km-long 7-core spooled fiber. This study further establishes multicore fiber (MCF) networks as a promising platform for ultrastable frequency transfer, serving as an important step toward incorporating precision time and frequency distribution into future MCF communication infrastructures.
Paper Structure (8 sections, 7 figures)

This paper contains 8 sections, 7 figures.

Table of Contents

  1. Introduction
  2. Experiments
  3. Conclusion
  4. Cavity-stabilized laser
  5. Amplifier inter-channel phase correlation measurements
  6. Instability from pump power fluctuation
  7. Fractional frequency instability with other amplifier channel combinations
  8. Phase noise spectra of the stabilized links

Figures (7)

  • Figure 1: (a) Left: core-layout and labeling scheme of the 4-core fibers in the amplifier. Right: simplified illustration of the amplifier configuration. MC-ISO: multicore isolator. MC-PC: muticore pump combiner. MC-EDF: multicore erbium-doped fiber. MC-GFF: multicore gain-flattening filter. (b) Core-layout of the 40 km 7-core fiber. (c) Schematic of the Doppler-canceled link setup. Col: collimator. BS: beam splitter. PD: photodetector. AOM: acousto-optic modulator. CIR: fiber circulator. FI/FO: fan-in fan-out devices.
  • Figure 2: (a) Change in pump power under external modulation and the corresponding change in relative phase between the amplified signals of the two amplifier channels. (b) Fractional frequency instability limit estimated from the pump power fluctuation effect for each amplifier channel.
  • Figure 3: Modified Allan deviation characterizing the long-term performance of the amplifier alone and with the 40 km 7-core fiber.
  • Figure S1: (a) Schematic illustration of the inter-channel correlation measurements of the MCF amplifier. (b) Modified Allan deviation estimated from the inter-channel phase correlation measurements. (c) Phase noise spectrum of the measured correlation level.
  • Figure S2: (a) Schematic illustration of the pump power vs. phase change measurements of the MCF amplifier. (b) The measured pump power change and (c) the corresponding phase change.
  • ...and 2 more figures