Pulse laser generator and optical fiber sensor system using same

Patent metadata

Field	Value
Publication number	US-9312656-B2
Application number	US-201314404116-A
Country	US
Kind code	B2
Filing date	May 31, 2013
Priority date	Jun 1, 2012
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

Disclosed are a pulse laser generator and an optical fiber sensor system using the same. The optical fiber sensor system includes a main optical coupler that receives pulse laser light generated from a pulse laser generator from a first input terminal, branches the light to first and second output terminals to output, and outputs, through a third output terminal, light input reversely from the first and second output terminals, a reference optical fiber that is connected to the first output terminal, a multi-point sensing optical fiber unit that is connected to the second output terminal, and in which optical fibers are connected in series or in parallel corresponding to a plurality of sensing points, an optical detection unit that is connected to the third output terminal, and a diagnosis processing unit that detects a change of the physical quantity for the sensing points from signals from the optical detection unit.

First claim

The invention claimed is:

1. An optical fiber sensor system using a pulse laser, comprising:
a pulse laser generator that generates and outputs pulse laser light;
a main optical coupler that receives the pulse laser light generated and outputted from the pulse laser generator from a first input terminal, branches the received light to a first output terminal and a second output terminal to output the branched light, and outputs, through a third output terminal, light input reversely from each of the first output terminal and the second output terminal;
a reference optical fiber that is connected to the first output terminal and reflects light input through the main optical coupler to provide a reference optical signal, and extends by a predetermined length as an optical fiber;
a multi-point sensing optical fiber unit that is connected to the second output terminal, and in which optical fibers are connected in series or in parallel corresponding to a plurality of sensing points so as to measure a physical quantity to be measured for each of the plurality of sensing points;
an optical detection unit that converts an optical signal input through the third output terminal into an electrical signal; and
a diagnosis processing unit that detects a change of the physical quantity which is set for the sensing points from a signal output from the optical detection unit,
wherein the multi-point sensing optical fiber unit is formed in such a manner that the optical fibers are mutually bonded in series and a bonded portion is the sensing point or the optical fibers having mutually different lengths are mutually coupled in parallel so that light made incident through the second output terminal is branched to be reflected at a termination of the optical fiber, or light is selectively made incident to the optical fibers having mutually different lengths by a multiplexer.

2. The optical fiber sensor system of claim 1 , wherein the pulse laser generator includes:
a pumping light source that emits light;
an amplification optical fiber doped with ytterbium or erbium that amplifies light made incident from the pumping light source;
an optical fiber resonator that forms a ring type resonator using the optical fiber so that light supplied from the pumping light source resonates while being circulated through the amplification optical fiber;
an optical input unit that causes light emitted from the pumping light source to be incident to the optical fiber resonator;
an output optical coupler that is coupled to the optical fiber resonator to output pulse light generated from the optical fiber resonator through a main output terminal;
a phase synchronization unit that is coupled to the optical fiber resonator to synchronize a phase; and
a dispersion compensation scanning unit that is coupled to both ends of the optical fiber resonator to compensate for dispersion of input light so that a pulse width is adjusted narrow, and is controlled by the diagnosis processing unit so that a resonance length of the optical fiber resonator is variable.

3. The optical fiber sensor system of claim 2 , wherein
the dispersion compensation scanning unit includes a first mirror that is disposed to reflect light made incident through one end of the optical fiber resonator in a direction different from an incident path, a second mirror that is disposed to face the first mirror and is disposed to reflect light made incident from the first mirror in a direction different from that of the first mirror, a third mirror that is disposed to reflect light made incident from the second mirror in a direction different from that of the second mirror, and a fourth mirror that is disposed to reflect light made incident from the third mirror so that the reflected light is made incident to the other end of the optical fiber resonator,
a grating having an uneven pattern is formed on surfaces of the first to fourth mirrors to compensate for dispersion of light, and
a separation distance is formed to be variable in a horizontal direction of the third and fourth mirrors with respect to the first and second mirrors, and the second and third mirrors are formed to be movable relative to the first and fourth mirrors in a vertical direction.

4. The optical fiber sensor system of claim 2 , wherein
the dispersion compensation scanning unit includes an optical circulator that is coupled to one end of the optical fiber resonator to output light made incident through the optical fiber resonator to an adjustment output terminal and causes light made incident through the adjustment output terminal to be incident to the other end of the optical fiber resonator, a fifth mirror that reflects light emitted through the adjustment output terminal of the optical circulator in a direction different from an incident path, a sixth mirror that is disposed to face the fifth mirror and disposed to reflect light made incident from the fifth mirror in a direction different from that of the fifth mirror, and a reference mirror that is disposed to reflect light made incident from the sixth mirror to the sixth mirror,
a grating having an uneven pattern is formed on surfaces of the fifth and sixth mirrors to compensate for dispersion of light, and
the reference mirror is controlled by the diagnosis processing unit and provided to be movable so that a separation distance between the reference mirror and the sixth mirror is variable.

5. A pulse laser generator that generates pulse laser light, comprising:
a pumping light source that emits light;
an amplification optical fiber doped with ytterbium or erbium that amplifies light made incident from the pumping light source;
an optical fiber resonator that forms a ring type resonator using the optical fiber so that light supplied from the pumping light source resonates while being circulated through the amplification optical fiber;
an optical input unit that causes light emitted from the pumping light source to be incident to the optical fiber resonator;
an output optical coupler that is coupled to the optical fiber resonator to output pulse light generated from the optical fiber resonator through a main output terminal;
a phase synchronization unit that is coupled to the optical fiber resonator to synchronize a phase; and
a dispersion compensation scanning unit that is coupled to both ends of the optical fiber resonator to compensate for dispersion of input light so that a pulse width is adjusted narrow, and is controlled by a diagnosis processing unit so that a resonance length of the optical fiber resonator is variable,
wherein
the dispersion compensation scanning unit includes a first mirror that is disposed to reflect light made incident through one end of the optical fiber resonator in a direction different from an incident path, a second mirror that is disposed to face the first mirror and is disposed to reflect light made incident from the first mirror in a direction different from that of the first mirror, a third mirror that is disposed to reflect light made incident from the second mirror in a direction different from that of the second mirror, and a fourth mirror that is disposed to reflect light made incident from the third mirror so that the reflected light is made incident to the other end of the optical fiber resonator,
a grating having an uneven pattern is formed on surfaces of the first to fourth mirrors to compensate for dispersion of light, and
a separation distance is formed to be variable in a horizontal direction of the third and fourth mirrors with respect to the first and second mirrors, and the second and third mirrors are formed to be movable relative to the first and fourth mirrors in a vertical direction.

6. A pulse laser generator that generates pulse laser light, comprising:
a pumping light

Assignees

• Korea Ind Tech Inst

Inventors

• Lee Ho Jae
• Joo Ki Nam

Classifications

• G01K11/3206

  at discrete locations in the fibre, e.g. using Bragg scattering · CPC title

• H01S3/1618

  ytterbium · CPC title

• H01S3/1112

  Passive mode locking · CPC title

• G01L11/025

  using a pressure-sensitive optical fibre · CPC title

• G01D5/35309

  using multiple waves interferometer · CPC title