Equipment and method for measuring loss and crosstalk that occur in optical fiber transmission line
US-2024377282-A1 · Nov 14, 2024 · US
Apparatus and method for measuring the delay time difference between propagation modes
US12517008B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-12517008-B2 |
| Application number | US-202118688185-A |
| Country | US |
| Kind code | B2 |
| Filing date | Sep 15, 2021 |
| Priority date | Sep 15, 2021 |
| Publication date | Jan 6, 2026 |
| Grant date | Jan 6, 2026 |
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Abstract
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The present disclosure relates to a device, including: a first light source for outputting incident light to a measured optical fiber or optical device; a second light source for outputting local light for being multiplexed with transmitted light through the measured optical fiber or optical device; and a signal processing unit for performing digital signal processing on a light-receiving signal I(t) obtained by multiplexing the transmitted light and the local light, wherein the signal processing unit is configured to calculate an autocorrelation function between the light-receiving signal I(t) and a signal I(t+τ) obtained by shifting the light-receiving signal by a time τ, and to measure a delay time difference between propagation modes in the measured optical fiber or optical device, from a peak position of the autocorrelation function.
First claim
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The invention claimed is: 1 . A device, comprising: a first light source for outputting incident light to a measured optical fiber or optical device; a second light source for outputting local light for being multiplexed with transmitted light through the measured optical fiber or optical device; and a signal processing unit for performing digital signal processing on a light-receiving signal I(t) obtained by multiplexing the transmitted light and the local light, wherein the signal processing unit is configured to calculate an autocorrelation function between the light-receiving signal I(t) and a signal I(t+τ) obtained by shifting the light-receiving signal by a time τ, and to measure a delay time difference between propagation modes in the measured optical fiber or optical device, from a peak position of the autocorrelation function. 2 . The device according to claim 1 , wherein a coherence time of the incident light is shorter than a propagation mode delay time in the measured optical fiber or optical device, and a coherence time of the local light is longer than the propagation mode delay time in the measured optical fiber or optical device. 3 . The device according to claim 1 , wherein the signal processing unit is configured to obtain mode dispersion in the measured optical fiber or optical device, using a distribution of peaks of an autocorrelation function R(τ) with respect to τ. 4 . The device according to claim 3 , wherein the signal processing unit is configured to obtain mode dispersion in the measured optical fiber or optical device, from a standard deviation σ obtained using the following equation [ Math . C4 ] R ( τ ) ∝ e - τ 2 4 σ 2 . ( C 4 ) 5 . A method comprising: injecting incident light from a first light source into a measured optical fiber or optical device; multiplexing transmitted light of the measured optical fiber or optical device with local light output from a second light source different from the first light source; calculating, by a signal processing unit, an autocorrelation function R(τ) between a light-receiving signal I(t), obtained by multiplexing the transmitted light and the local light, and a signal I(t+τ), obtained by shifting the light-receiving signal by a time τ, and measuring a delay time difference between propagation modes in the measured optical fiber or optical device, by a signal processing unit using a peak position of the autocorrelation function R(τ) with respect to τ. 6 . The method according to claim 5 , wherein the signal processing unit is configured to measure mode dispersion in the measured optical fiber or optical device, using a distribution of peaks of the autocorrelation function R(τ) with respect to τ.
Assignees
Inventors
Classifications
- G01M11/336Primary
by measuring polarization mode dispersion [PMD] · CPC title
- G01M11/331Primary
by using interferometer · CPC title
using an out-of-service signal (H04B10/071 takes precedence) · CPC title
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- What does patent US12517008B2 cover?
- The present disclosure relates to a device, including: a first light source for outputting incident light to a measured optical fiber or optical device; a second light source for outputting local light for being multiplexed with transmitted light through the measured optical fiber or optical device; and a signal processing unit for performing digital signal processing on a light-receiving signa…
- Who is the assignee on this patent?
- Ntt Inc
- What technology area does this patent fall under?
- Primary CPC classification G01M11/336. Mapped technology areas include Physics.
- When was this patent published?
- Publication date Tue Jan 06 2026 00:00:00 GMT+0000 (Coordinated Universal Time) (B2). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 7 related publications on this page (citations in our corpus or others sharing the same primary CPC).