Measuring device for polarization-maintaining optical fiber spindle differential delay

Patent metadata

Field	Value
Publication number	US-11159233-B2
Application number	US-202117194290-A
Country	US
Kind code	B2
Filing date	Mar 7, 2021
Priority date	Mar 28, 2019
Publication date	Oct 26, 2021
Grant date	Oct 26, 2021

Abstract

A measurement device for polarization-maintaining optical fiber spindle difference delay is provided. The measurement device comprises a polarization-maintaining fiber (PM) Sagnac interferometer, a signal generator, a microwave detector, a microprocessor. The PM Sagnac interferometer comprises a laser, a photoelectric modulator, and a PM fiber coupler that are connected in sequence. The PM Sagnac interferometer further comprises an optical fiber interface J1 and an optical fiber interface J2 arranged at the two output ends of the PM fiber coupler, a PM fiber to be measured located between the fiber interface J1 and the fiber interface J2, and a photodetector arranged at the other output end of the PM fiber coupler.

First claim

What is claimed is:

1. A measurement device for polarization-maintaining (PM) optical fiber spindle differential delay, comprising:
a PM fiber Sagnac interferometer;
a signal generator;
a microwave detector; and
a microprocessor;
wherein the PM fiber Sagnac interferometer comprises a laser, a photoelectric modulator and a PM fiber coupler, which are connected in sequence;
the PM fiber Sagnac interferometer further comprises a first fiber interface and a second fiber interface arranged respectively at a first output port and a second output port of the PM fiber coupler, a to-be-measured PM fiber located between the first fiber interface and the second fiber interface, and a photoelectric detector arranged at a third output port of the PM fiber coupler;
a low-coherence linear polarized light emitted by the laser is applied with a RF (radio frequency) signal by the photoelectric modulator, and divided into two output lights;
a first output light of the two output lights along a fast axis of the PM fiber coupler enters the to-be-measured PM fiber through the first fiber interface and a first end of the to-be-measured PM fiber, and transmits along the fast axis of the to-be-measured PM fiber; a second output light of the two output lights along the fast axis of the PM fiber coupler is coupled to a slow axis of the to-be-measured PM fiber through the second fiber interface and a second end of the to-be-measured PM fiber; the two output lights are transmitted in opposite directions and in different axes;
the first output light in the fast axis of the to-be-measured PM fiber is redirected into the slow axis of the to-be-measured PM fiber through the second fiber interface when the first output light arrives at the second end of the to-be-measured PM fiber; the second output light in the slow axis of the to-be-measured PM fiber will not change transmission axis when entering the slow axis of the PM fiber coupler;
the microwave detector is arranged at an output end of the photoelectric detector and is configured to detect the power of the RF signal output by the photoelectric detector;
the microprocessor is connected to the microwave detector, and is configured to calculate a light delay generated by the to-be-measured PM fiber according to an output signal of the microwave detector.

2. The measurement device according to claim 1 , wherein the laser is a broad-spectrum light source with a coherence length less than 30 μm; the coherence length of the laser is much smaller than the optical path difference caused by different propagation constants of the fast and slow axes of the to-be-measured PM fiber.

3. The measurement device according to claim 2 , wherein the laser emits linearly polarized light.

4. The measurement device according to claim 1 , wherein the PM fiber coupler is a 2×2, 3 dB PM fiber coupler.

5. The measurement device according to claim 2 , wherein two fibers on the PM fiber coupler that connect to the first fiber interface and second fiber interface have identical length.

6. The measurement device according to claim 1 , wherein the optical fiber spindle differential delay is calculated by the microprocessor based on the following formula:

τ
=

1



f

R
⁢
F
⁢
0

-

f

R
⁢
F
⁢
1



wherein, f RF0 and f RF1 are the frequency values at which the voltage output by the adjacent microwave detector is 0.

Assignees

• Univ Zhejiang

Inventors

• Jin Xiaofeng
• Qin Donglin
• Zhang Chenghui
• Jin Xiangdong
• Yu Xianbin
• Zheng Shilie
• Zhang Xianmin
• Cong Bo

Classifications

• G01M11/331

  by using interferometer · CPC title

• G02B6/024

  with polarisation maintaining properties · CPC title

• H04B10/503

  Laser transmitters · CPC title

• H04B10/0795 Primary

  Performance monitoring; Measurement of transmission parameters · CPC title

• H04B10/0731 Primary

  Testing or characterisation of optical devices, e.g. amplifiers · CPC title