Vibration sensing over passive optical networks (PONs) using forwarding optical phase retrieval and time-domain multiplexed (TDM) switching

Patent metadata

Field	Value
Publication number	US-12405136-B2
Application number	US-202217713167-A
Country	US
Kind code	B2
Filing date	Apr 4, 2022
Priority date	Apr 5, 2021
Publication date	Sep 2, 2025
Grant date	Sep 2, 2025

Abstract

Aspects of the present disclosure describe systems and methods that advantageously enable vibration-induced optical phase measurement at a centralized optical line terminal (OLT) in a PON architecture. In sharp contrast to existing distributed fiber sensing systems and methods, the optical phase measurements of the present disclosure do not rely on back scattering mechanisms and maintain a sufficient optical signal to noise ratio (OSNR) even after round-trip splitting loss in the PON.

First claim

The invention claimed is:

1. A system for vibration sensing over passive optical networks (PON) using forwarding optical phase retrieval and time domain multiplexed (TDM) switching, the system comprising:
an optical line terminal (OLT);
a plurality of optical network units (ONUs);
a passive optical network optically connecting the OLT to the ONUs);
wherein the plurality of ONUs each include an optical switch optically connected to the PON and to an optical reflector; and
said OLT is configured to provide a continuous optical phase interferometry signal to the PON and receive signals reflected by the plurality of optical reflectors.

2. The system of claim 1 wherein the OLT includes a coherent receiver for reception/detection of the reflected signals.

3. The system of claim 2 wherein the OLT includes a single laser for both sensing and local oscillation.

4. The system of claim 3 further configured to selectively activate an optical switch in each one of the plurality of ONUs, such that only one of the plurality of ONUs provides a reflected signal at a given point of time.

5. The system of claim 4 wherein the PON carries telecommunications traffic simultaneously with the continuous optical phase interferometry signal and any reflected signal(s).

6. The system of claim 5 wherein the PON includes N ONUs a 1×N splitter, a single feeder fiber optically connecting the OLT to the 1×N splitter and N drop fibers optically connecting the 1×N splitter to each individual ONU, respectively.

7. The system of claim 6 wherein the OLT determines reflection sources other than the ONU.

8. The system of claim 6 wherein the continuous optical phase interferometry signal provided to the PON is reflected back to the OLT for detection on a same fiber path on which it was provided.

Assignees

• Nec Lab America Inc
• Nec Corp

Inventors

• Huang Yue-Kai
• Ip Ezra
• Wang Ting

Classifications

• H04B10/61

  Coherent receivers · CPC title

• H04B10/071 Primary

  using a reflected signal, e.g. using optical time domain reflectometers [OTDR] · CPC title

• G01H9/004

  using fibre optic sensors (light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125) · CPC title

• H04B10/0773

  Network aspects, e.g. central monitoring of transmission parameters · CPC title

• G01D5/35361 Primary

  using elastic backscattering to detect the measured quantity, e.g. using Rayleigh backscattering · CPC title