KR101975521B1 - Optical fiber interrogator using wavelength variable optical device - Google Patents

Abstract

The present invention relates to an optical fiber interrogator using an optical device capable of optical wavelength conversion and, more specifically, to an optical fiber interrogator using an optical device capable of optical wavelength conversion, which has a wavelength conversion light source function by changing a reflection wavelength by changing light intensity of pump light and performs a high resolution function. The optical fiber interrogator using the optical device capable of optical wavelength conversion includes a wideband light source unit, a first light transmitting unit, a first optical circulator, a second light transmitting unit, a first optical device, a third light transmitting unit, a second optical circulator, a fourth light transmitting unit, a second optical device, a pump light output unit, a fifth light transmitting unit, and a light collection unit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an optical fiber interrogator using a wavelength variable optical device,

The present invention relates to an optical fiber interrogator using an optical wavelength tunable optical device, and more particularly, to an optical fiber interrogator using an optical wavelength tunable optical fiber, and more particularly, to an optical fiber interrogator using an optical wavelength variable optical fiber, The present invention relates to an optical fiber interrogator using an optical wavelength tunable optical device capable of exhibiting high resolution as well as having a wavelength variable function as a core element required for a wavelength variable light source.

The optical fiber sensor measures changes in the characteristics of light such as light intensity, phase, wavelength, and polarization state and converts it into displacement, velocity, temperature, humidity, strain, pressure, current, voltage, Or a sensor that can be measured in a high current environment.

The optical fiber sensor is capable of high sensitivity, high precision measurement and telemetry in a noncontact manner, can measure almost all physical quantities, can transmit low light loss to a desired distance, and can perform optical measurement without exposing light to the outside.

Such an optical fiber sensor changes the refractive index of the core by exposing ultraviolet rays to a core of a part of the optical fiber, and the change of the periodic refractive index induces reflection of the proceeding light at a specific wavelength. At this time, the reflected wavelength is called Bragg wavelength, and the Bragg wavelength is determined by the spatial periodicity in which the effective refractive index and the refractive index in the core region change. (Reflection, temperature, pressure, etc.) that can affect the effective index of refraction or the periodicity, and can have different reflected wavelengths by measuring the reflected light from the optical fiber sensor or observing the transmitted spectrum, The change can be measured.

The optical sensing method using a wavelength selective optical element such as an optical fiber sensor is a commonly used measurement method in which light output from a light source is incident on an optical element having wavelength selectivity and a reflected light having a specific wavelength is measured to measure a physical quantity The system is called an interrogator.

The interrogator is used as a method of dispersion measurement for the diagnosis of soundness of building or multipoint measurement, and it is used to measure various physical quantities such as temperature and strain.

The above-described interrogator is generally implemented by a technique using a multi-wavelength light source and a spectroscope, and a technique using a photodetector as a variable wavelength light source and a light receiving element.

Using a dual-wavelength light source and a spectroscope, a broadband source simultaneously emits multiple wavelengths through an optical fiber, and the wavelength of the light reflected from the FBG or wavelength-selective optical device is measured through a spectroscope, It is a technique to measure change of physical quantity.

A technique using a photodetector, which is a variable wavelength light source and a light receiving element, is a technique in which the wavelength of the emitted light is separated by time, and the light reflected from the FBG or an optical element having wavelength selectivity is measured by a light receiving element having no wavelength selectivity .

The conventional technique using the multi-wavelength light source and the spectroscope requires a high-resolution spectroscope because it can distinguish the reflected light of an optical device having wavelength selectivity. Further, in order to drive at a high speed, an additional driving circuit is required, which raises a problem that the system price is increased.

The technique using a photodetector, which is a variable wavelength light source and a light receiving element, maintains a high-speed measurement but requires an expensive variable wavelength light source, and emits light having a line width narrower than the spectrum reflected by an optical element having wavelength selectivity An element having a wavelength filter function having an expensive narrow line width is indispensable. In addition, stability is a problem for the wavelength variable light source to operate at high speed, and the accuracy of the synchronization directly affects the analysis result.

Korean Patent Publication No. 10-2005-0025760 Korea Patent Publication No. 10-2009-0050208 Korea Patent Publication No. 10-2011-0112086 Korean Patent Publication No. 10-2015-0146468

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a wavelength tunable light source that does not use a technique using a conventional multichromatic light source and a spectroscope or a technique using a variable wavelength light source and a photodetector, A variable wavelength light source function as a core element required for a wavelength variable light source and an optical fiber interrogator using an optical wavelength variable optical element capable of exhibiting high resolution through an optical element having a very narrow line width .

In addition, the present invention provides an optical fiber interrogator using an optical wavelength tunable optical system that can be implemented as a low-cost simple system without expensive high-resolution spectroscope or expensive high-speed wavelength variable light source required in conventional interrogators It has its purpose.

In addition, the present invention is an optical element having wavelength selectivity, which can be manufactured easily by applying a technique using FBG (Fiber Bragg Grating) as it is, and can be fabricated with various wavelengths, and has a wavelength variable reactivity And to provide an optical fiber interrogator using an optical device capable of performing optical signal processing with simple optical wavelength tuning.

According to an aspect of the present invention, there is provided an optical fiber interrogator using an optical wavelength tunable optical device, the optical fiber interrogator comprising: a broadband light source for outputting a reference light having a wide wavelength range; A first optical transmission unit for transmitting the reference light output from the wideband light source unit; A first port connected to the first light transmitting portion, receiving the reference light transmitted through the first light transmitting portion, outputting the received reference light to the second port, and outputting the first reflected light, which is input to the second port, A first optical circulator for outputting a signal to a port; A second optical transmission unit for transmitting the reference light output from the second port of the first optical circulator; A first optical element formed in the second optical transmission portion and selectively reflecting only light of a specific wavelength band from the plurality of wavelength bands included in the reference light passing through the second optical transmission portion toward the first optical circulator; Wow; A third optical transmission unit that receives a first reflected light input to a second port of the first optical circulator and output to a third port of the first optical circulator; A first port connected to the third optical transmission portion and configured to receive the first reflected light transmitted through the third optical transmission portion, to output the received first reflected light to the second port, A second optical circulator for outputting the reflected light to the third port; A fourth optical transmission unit transmitting a first reflected light output from a second port of the second optical circulator; And an output intensity of the pump light, which is formed in the fourth light transmitting portion and that is externally input to selectively reflect the light of the wavelength band corresponding to the first reflected light passing through the fourth light transmitting portion toward the second optical circulator, A second optical element whose refractive index is changed according to the refractive index; A pump light output unit for adjusting the intensity of the pump light so as to vary a specific wavelength band reflected by the second optical device and outputting the adjusted intensity; A fifth optical transmission unit that receives a second reflected light input to a second port of the second optical circulator and output to a third port of the second optical circulator; And a light receiving unit receiving the second reflected light transmitted through the fifth light transmitting unit.

The first optical device includes a fiber Bragg grating.

And a determination unit that determines a wavelength band to be received by the light receiving unit, wherein the pump light output unit adjusts the intensity of the pump light according to a value of an applied current, and the determination unit determines whether the second reflected light is received And the wavelength band of the second reflected light is determined by using the current value applied to the pump light output section.

The third optical transmission unit may further include an optical amplifier for amplifying the first reflected light output from the third port of the first optical circulator.

According to another aspect of the present invention, there is provided an optical fiber interrogator using an optical wavelength tunable optical device, including: a broadband light source for outputting a reference light having a wide wavelength range; A first optical transmission unit for transmitting the reference light output from the wideband light source unit; A first port connected to the first light transmitting portion, receiving the reference light transmitted through the first light transmitting portion, outputting the received reference light to the second port, and outputting the first reflected light, which is input to the second port, A first optical circulator for outputting a signal to a port; A second optical transmission unit for transmitting the reference light output from the second port of the first optical circulator; And a second optical transmission unit for receiving light of a predetermined wavelength band from the plurality of wavelength bands included in the reference light passing through the second optical transmission unit to selectively reflect the light of a specific wavelength band toward the first optical circulator, A first optical element whose refractive index is changed according to an output intensity of the pump light; A pump light output unit for adjusting the intensity of the pump light toward the first optical device so as to vary a specific wavelength band reflected from the first optical device; A third optical transmission unit that receives a first reflected light input to a second port of the first optical circulator and output to a third port of the first optical circulator; A first port connected to the third optical transmission portion and configured to receive the first reflected light transmitted through the third optical transmission portion, to output the received first reflected light to the second port, A second optical circulator for outputting the reflected light to the third port; A fourth optical transmission unit transmitting a first reflected light output from a second port of the second optical circulator; A second optical element formed in the fourth optical transmission unit and selectively reflecting the light of a wavelength band corresponding to the first reflected light passing through the fourth optical transmission unit to the second optical circulator; A fifth optical transmission unit that receives a second reflected light input to a second port of the second optical circulator and output to a third port of the second optical circulator; And a light receiving unit receiving the second reflected light transmitted through the fifth light transmitting unit.

The second optical device includes a fiber Bragg grating.

And a determination unit that determines a wavelength band to be received by the light receiving unit, wherein the pump light output unit adjusts the intensity of the pump light according to a value of an applied current, and the determination unit determines whether the second reflected light is received And the wavelength band of the second reflected light is determined by using the current value applied to the pump light output section.

The third optical transmission unit may further include an optical amplifier for amplifying the first reflected light output from the third port of the first optical circulator.

The optical fiber interrogator using an optical wavelength tunable optical device according to the present invention can function as a wavelength variable light source, which is a core device required for a wavelength variable light source, because it can control wavelength tunable characteristics with light intensity, Because it is a device, high-resolution characteristics can be maintained.

In addition, the optical fiber interrogator using an optical wavelength tunable optical device according to the present invention can perform the role of a conventional interrogator without the expensive high-resolution spectroscope or the expensive high-speed wavelength variable light source required in the existing interrogator, Since a tunable light source or a spectroscope is not used, a low cost interrogator can be realized as a simplified system.

In addition, the optical fiber interrogator using an optical wavelength tunable optical device according to the present invention is an optical device having the existing wavelength selectivity and can be manufactured easily because it uses the characteristics of the FBG as it is, and can be manufactured with various wavelengths. Because of its excellent linearity and variable wavelength reactivity, it is not only simple to process the signal of the sensor, but also has the advantage of replacing the optical fiber system or facilitating implementation because it is an optical fiber device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an optical fiber interrogator using an optical wavelength tunable optical device according to a first embodiment of the present invention; FIG.
FIG. 2 is a diagram illustrating an optical fiber interrogator using an optical wavelength tunable optical device according to a second embodiment of the present invention. FIG.
FIGS. 3A to 3E are diagrams for explaining a reflected wavelength determination process of an optical fiber interrogator using an optical wavelength tunable optical device according to the present invention at a first temperature condition; FIG.
FIGS. 4A to 4E are diagrams for explaining a reflected wavelength determination process of an optical fiber interrogator using an optical wavelength tunable optical device according to the present invention at a second temperature condition. FIG.
5 is a graph showing a temperature response curve measured by applying an optical fiber interrogator using an optical wavelength tunable optical device according to the present invention.

Hereinafter, an optical fiber interrogator using an optical wavelength tunable optical device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an optical fiber interrogator using an optical wavelength tunable optical device according to a first embodiment of the present invention. 1, an optical fiber interrogator using an optical wavelength tunable optical device according to a first embodiment of the present invention includes a broadband light source unit 10, a first optical transmission unit 20, a first optical circulator 30, the second optical transmission unit 40, the first optical device 50, the third optical transmission unit 60, the second optical circulator 70, the fourth optical transmission unit 80 A second optical element 90, a pump light output section 100, a fifth light transmission section 110, a light receiving section 120, and a judging section.

The broadband light source 10 outputs a reference light having a wide wavelength range. The broadband light source 10 has a wide wavelength band including a plurality of different wavelength bands, and outputs the reference light to the first optical transmission unit 20 in the form of a laser beam.

The first optical transmission portion 20 is connected to the broadband light source portion 10 so that the reference light outputted from the broadband light source portion 10 as an optical fiber is transmitted to the first optical circulator 30, Is connected to the first port (31) of the lighter (30).

The first optical circulator 30 includes a first port 31 to a third port 33 and outputs an optical signal input to one port to the port on the other adjacent port. The first optical circulator 30 receives the reference light transmitted through the first optical transmission unit 20 by connecting the first port 31 to the end of the first optical transmission unit 20. The received reference light is output to the second port 32 and the first reflected light reflected by the first optical element 50 and input to the second port 32 is output to the third port 33 do.

One end of the second optical transmission unit 40 is connected to the second port 32 and the other end thereof is extended by a predetermined length so as to transmit the reference light output from the second port 32 of the first optical circulator 30 .

The first optical element 50 is formed in the second optical transmission portion 40 and is formed of a plurality of wavelength bands of a specific wavelength band? _B among the plurality of wavelength bands included in the reference light passing through the second optical transmission portion 40 And selectively reflects only the light toward the first optical circulator 30 side. Hereinafter, the light reflected by the first optical element 50 is referred to as a first reflected light.

In this embodiment, the first optical element 50 exposes the ultraviolet rays to a certain region of the optical fiber core of the first light transmitting portion 20 to change the refractive index of the core, Fiber Bragg grating (FBG) that reflects only the light of the band is applied, but it is needless to say that other types of optical devices can be applied.

The third optical transmitter 60 receives the first reflected light that is input to the second port 32 of the first optical circulator 30 and is output to the third port 33 of the first optical circulator 30 One end is connected to the third port 33 of the first optical circulator 30 and the other end is connected to the first port 71 of the second optical circulator 70.

Although not shown in the drawing, the third optical transmitter 60 may further include an optical amplifier 61 amplifying the first reflected light output from the third port 33 of the first optical circulator 30 have.

The second optical circulator 70 receives the first reflected light transmitted through the third optical transmission unit 60 by connecting the first port 71 to the third optical transmission unit 60. The second reflected light reflected by the second optical element 90 and input to the second port 72 is reflected by the third port 73 to the second port 72, .

The fourth optical transmission unit 80 is connected to the second optical circulator 70 so that the first optical transmitter 90 transmits the first reflected light output from the second port 72 of the second optical circulator 70 to the second optical circulator 90 70, and the other end is extended by a predetermined length.

The second optical element 90 is formed in the fourth optical transmission unit 80 and transmits the light of the wavelength band corresponding to the first reflected light passing through the fourth optical transmission unit 80 to the second optical circulator 70, The refractive index is changed according to the intensity of the pump light input from the outside.

Hereinafter, the light reflected by the second optical element 90 is referred to as a second reflected light.

The second optical element 90 has a refractive index that is set so as to reflect light of a wavelength band set at the time of fabrication unless the pump light is inputted from the outside, but has a characteristic that the refractive index changes when the output intensity of the pump or input is changed . That is, the second optical element 90 can reflect only light of a specific wavelength band when there is no pump light, but it can selectively reflect light of a plurality of wavelength bands or only light of a desired wavelength band by adjusting the intensity of the input pump light It is possible to selectively reflect it.

The pump light output unit 100 is coupled to a point of the fourth optical transmission unit 80 between the second optical element 70 and the second optical element 90 through the WDM coupler 81, 90). The pump light output unit 100 adjusts the intensity of the pump light so as to vary a specific wavelength band reflected by the second optical device 90 and outputs the output intensity of the pump light output from the pump light output unit 100 to the pump light output unit 100. [ (100). Preferably, the pump light output unit 100 gradually increases or decreases the applied current so that the output intensity of the pump light gradually increases or decreases.

The fifth optical transmission unit 110 receives the second reflected light that is input to the second port 72 of the second optical circulator 70 and output to the third port 73 of the second optical circulator 70, One end is connected to the third port of the second optical circulator 70 and the other end is connected to the light receiving unit 120 so as to transmit the light to the light receiving unit 120.

The light receiving unit 120 receives the second reflected light transmitted through the fifth light transmitting unit 110.

The determination unit determines the wavelength band to be received by the light receiving unit 120 and determines the wavelength band of the second reflected light by using the current value applied to the pump light output unit 100 at the time point when the second reflected light is received by the light receiving unit 120 . To this end, the judging unit judges the wavelength of light received by the light receiving unit 120 through a lookup table (LUT) in which the current value applied to the pump light output unit 100 and the wavelength information corresponding to each current value are respectively matched can do.

When the wavelength of the first reflected light reflected by the first optical element 50 and the wavelength of the second reflected light reflected by the second optical element 90 do not coincide with each other in the light receiving unit 120 The second reflected light is not received, and the wavelength of the first reflected light reflected by the first optical element 50 and the wavelength of the second reflected light of the second optical element 90 (i.e., when the current value is not coincident with the current value corresponding to the wavelength of the second reflected light) (When the current value applied to the pump light output section 100 coincides with the current value corresponding to the wavelength of the second reflected light), the second reflected light is received. At this time, Compares the current value applied to the pump light output unit 100 when the second reflected light is received to the lookup table and extracts the wavelength information corresponding to the current value to determine the wavelength of the second reflected light.

Hereinafter, a process of determining the wavelength of the optical fiber interrogator using the optical wavelength tunable optical device according to the first embodiment of the present invention will be described.

The reference light output from the wideband light source 10 is reflected by the first optical element 50 only with a specific wavelength λ _B and is incident on the second optical element 90, The refractive index is changed according to the output intensity of the pump light applied to the pump light output unit 100, and the reflected wavelength is varied.

In the light receiving unit 120, the reflection wavelength of the second optical element 90, which varies according to the current value applied to the pump light output unit 100, is equal to the wavelength? _B of the light reflected by the first optical element 50 The wavelength of the second reflected light can be determined through the current value applied to the pump light output unit 100 at the instant when the reflected light signal is measured at the light receiving unit 120. [

When the reflection wavelength of the first optical element 50 changes due to the influence of the surrounding environment (temperature change, tensile force, compressive force, deforming force, etc.), the other current value applied to the pump- The reflected wave of the two optical elements 90 is changed so that the light reflected by the first optical element 50 is received by the light receiving unit 120. In this case, as described above, the optical signal is received by the light receiving unit 120 The reflected wave of the first optical element 50 or the wavelength of the optical signal received by the light receiving unit 120 can be determined and determined by grasping the current value applied to the pump light output unit 100. [

On the other hand, when the intensity of the received light exceeds a specific noise value, it is considered that the reflected light is measured, and the specific wavelength reflected by comparing the current value or the current value applied to the pump light output unit 100 at this time is determined .

The optical fiber interrogator using the optical wavelength tunable optical device according to the present invention can fabricate the first optical device 50 and the second optical device 90 in the same fabrication process, And the like.

In addition, the optical fiber interrogator using an optical wavelength tunable optical device according to the present invention does not use a technique using a conventional multi-wavelength light source and a spectroscope, or a technique using a photodetector as a variable wavelength light source and a light receiving device, It is possible to exhibit high resolution through a wavelength tunable light source function as a core element necessary for a wavelength variable light source and an optical element having a very narrow line width.

Further, the present invention is advantageous in that it can be implemented as a low-cost, simplified system without expensive high-resolution spectroscope or expensive high-speed wavelength variable light source required in existing interrogators.

FIG. 2 illustrates an optical fiber interrogator using an optical wavelength tunable optical device according to another embodiment of the present invention.

Referring to FIG. 2, an optical fiber interrogator using an optical wavelength tunable optical device according to a second embodiment of the present invention includes a broadband light source unit 10, a first optical transmission unit 20, a first optical circulator 30, the second optical transmission unit 40, the first optical device 50, the pump light output unit 60, the third optical transmission unit 70, the second optical circulator 80, A fourth optical transmission unit 90, a second optical device 100, a fifth optical transmission unit 110, a light receiving unit 120, and a determination unit.

The broadband light source 10 outputs a reference light having a wide wavelength range. The broadband light source 10 has a wide wavelength band including a plurality of different wavelength bands, and outputs the reference light to the first optical transmission unit 20 in the form of a laser beam.

The first optical transmission portion 20 is connected to the broadband light source portion 10 so that the reference light outputted from the broadband light source portion 10 as an optical fiber is transmitted to the first optical circulator 30, Is connected to the first port (31) of the lighter (30).

The first optical circulator 30 includes a first port 31 to a third port 33 and outputs an optical signal input to one port to the port on the other adjacent port. The first optical circulator 30 receives the reference light transmitted through the first optical transmission unit 20 by connecting the first port 31 to the end of the first optical transmission unit 20. The received reference light is output to the second port 32 and the first reflected light reflected by the first optical element 50 and input to the second port 32 is output to the third port 33 do.

One end of the second optical transmission unit 40 is connected to the second port 32 and the other end thereof is extended by a predetermined length so as to transmit the reference light output from the second port 32 of the first optical circulator 30 .

The first optical element 50 is formed in the second optical transmission portion 40 and transmits only the light of a specific wavelength band among the light of the plurality of wavelength bands included in the reference light passing through the second optical transmission portion 40, The refractive index is changed according to the intensity of the pump light input from the outside so as to selectively reflect the light to the side of the optical circulator 30.

The first optical element 50 has a refractive index that is set so as to reflect light in a predetermined wavelength band at the time of fabrication unless pump light (light for causing a refractive index change) is input from the outside, The refractive index is changed. In other words, the first optical element 50 can reflect only light of a specific wavelength band when there is no pump light, but it can selectively reflect light of a plurality of wavelength bands or light of a desired wavelength band by adjusting the intensity of the input pump light It is possible to selectively reflect it.

The pump light output unit 60 is coupled to a point of the second optical transmission unit 40 between the first optical circulator 30 and the first optical device 50 through the WDM coupler 61, 50). The pump light output unit 60 adjusts the intensity of the pump light so as to vary a specific wavelength band reflected by the first optical device 50 and outputs the output intensity of the pump light output from the pump light output unit 60 to the pump output unit 60. [ (60). ≪ / RTI > Preferably, the pump light output section 60 gradually increases or decreases the applied current so that the output intensity of the pump light gradually increases or decreases.

The pump light output section 60 for outputting the pump light to the first optical element 50 is provided with a WDM coupler (not shown) at one point of the second optical transmission section 40 between the first optical circulator 30 and the first optical element 50, (61) and outputs the pump light to the first optical element (50).

The third optical transmission portion 70 receives the first reflected light that is input to the second port 32 of the first optical circulator 30 and output to the third port 33 of the first optical circulator 30, One end of which is connected to the third port 33 of the first optical circulator 30 and the other end of which is connected to the first port 81 of the second optical circulator 80 .

The first reflected light that is input to the second port 32 of the first optical circulator 30 and output to the third port 33 of the first optical circulator 30 is transmitted to the second port 32 of the second optical circulator 30, The optical transmitter 71 further includes an optical amplifier 71 for amplifying the first reflected light output from the third port 33 of the first optical circulator 30, .

The second optical circulator 80 receives the first reflected light transmitted through the third optical transmission unit 80 by connecting the first port 81 to the third optical transmission unit 70. The second reflected light reflected by the second optical element 100 and input to the second port 82 is reflected by the third port 83, .

The fourth optical transmission unit 90 transmits the first reflected light output from the second port 82 of the second optical circulator 80 to the second optical device 100 to be described later, Is connected to the second port (82) of the lighter (80), and the other end extends a predetermined length.

The second optical element 100 is formed in the fourth optical transmitter 90 and transmits light of a wavelength band corresponding to the first reflected light passing through the fourth optical transmitter 90 to the second optical transmitter 80, As shown in FIG. In this embodiment, the second optical element 100 is an optical fiber Bragg grating, but it is needless to say that various types of optical elements can be applied.

The fifth optical transmission unit 110 receives the second reflected light that is input to the second port 72 of the second optical circulator 70 and output to the third port 73 of the second optical circulator 70, One end is connected to the third port of the second optical circulator 70 and the other end is connected to the light receiving unit 120 so as to transmit the light to the light receiving unit 120.

The light receiving unit 120 receives the second reflected light transmitted through the fifth light transmitting unit 110.

The determination unit determines the wavelength band to be received by the light receiving unit 120 and determines the wavelength band of the second reflected light by using the current value applied to the pump light output unit 60 at the time point when the second reflected light is received by the light receiving unit 120 . To this end, the judging unit judges the wavelength of the light received by the light receiving unit 120 through a lookup table (LUT) in which the current value applied to the pump light output unit 60 and the wavelength information corresponding to each current value are respectively matched do.

Hereinafter, a process of determining the wavelength of the optical fiber interrogator using the optical wavelength tunable optical device according to the first embodiment of the present invention will be described.

First, the reference light emitted from the broadband light source unit 10 is reflected by the first optical element 50 only with a specific wavelength, and the first reflected light is transmitted to the second optical element 100. At this time, the reflection wavelength of the first optical element 50 varies depending on the intensity of the pump light. At this time, the output intensity of the pump light is controlled by the current value applied to the pump light output unit 60, and the reflection wavelength of the first optical device 50 is determined by the current value applied to the pump light output unit 60. When the current value applied to the pump light output unit 60 is periodically changed, the reflection wavelength of the first optical device 50 is periodically varied. This is advantageous in that the first optical element 50 and the pump light output unit 60 can easily replace the functions of the conventional tunable light source, thereby realizing the interrogator at a low cost.

On the other hand, only when the first reflected light of a specific wavelength reflected by the first optical element 50 coincides with the intrinsic reflection wavelength of the second optical element 100 in the second optical element 100, 100, and the second reflected light reflected by the second optical element 100 is finally received by the light receiving portion 120.

The light receiving unit 120 receives the first reflected light reflected by the first optical device 50 varying according to the current value applied to the pump light output unit 60 and the wavelength of the second reflected light reflected by the second optical device 100 The determination unit may determine the wavelength of the second reflected light through the current value applied to the pump light output unit 60 at the moment when the second reflected light is measured by the light receiving unit 120. [

3A to 3E illustrate an environmental factor (temperature) applied to the first optical device 50 or the second optical device 100 by applying the optical fiber interrogator using the optical wavelength tunable optical device according to the present invention, The wavelength measurement process is shown in this variable situation. The first optical element 50 is adapted to reflect light of a first specific wavelength? _B1 at a first temperature T ₁ as shown.

First, the first optical element 50, the first temperature (T ₁₎ when the state is maintained in the state, the reflection wavelength of the first optical element 50, i.e., the first pump to measure the specific wavelength (λ _B1) The light receiving unit 120 sequentially or gradually increases the current applied to the output unit 60 to the initial current value I ₀ , the first current value I ₁ and the second current value I ₂ , It monitors the reception status. Since the optical signal is received in the light-receiving unit 120 when the current value applied to the pump light output unit 60 is the first current value I ₁ , the determination unit determines that the optical signal corresponding to the first current value I ₁ And extracts the wavelength information to determine a first specific wavelength? _B1 which is a reflection wavelength of the first optical element 50 when the first temperature T ₁ is in the state. 3B to 3D, red portions of the reflected light are respectively received by the light receiving portion when the current values applied to the pump light output portion 60 are the initial current value I ₀ and the second current value I ₂ , Quot; optical signal "

4A to 4E, when the temperature applied to the first optical element 50 is changed from the first temperature T ₁ to the second temperature T ₂ , the first optical element 50, (Blue display in Fig. 4A) to the second specific wavelength? _B2 at the first specific wavelength? _B1 (indicated by the dotted line in Fig. 4A) as shown in Fig.

The current to be applied to the pump light output section 60 is sequentially set to the initial current value I ₀ , the first current value I ₁ and the second current value I ₂ to detect the second specific wavelength λ _B2 Or gradually increases to monitor the reception of the optical signal to the light receiving unit 120. Then, the identification unit a second current value of the pump output current value is a second current value that is applied to the (60) (I ₂₎ when, since shown to be received optical signal to the light receiving portion 120 in a look-up table (I ₂₎ And determines the second specific wavelength? _B2 , which is the reflected wave field of the first optical element 50, at the second temperature (T ₂ ) state.

On the other hand, FIG. 5 shows the temperature response curve for the reflected wavelength reflected by the first optical element 50 under a plurality of temperature conditions as described above.

The illustrated temperature response curve has a linearity with respect to the current value applied to the pump light output section 60. Through the temperature response curve, the process of determining the wavelength band by knowing the temperature condition is inversely analyzed, The temperature information applied to the first optical element 50 can be inferred and determined based on the determination of the wavelength received by the light receiving unit 120 and the determined wavelength information when the temperature applied to the first optical element 50 varies.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It will be appreciated that other equivalent embodiments are possible.

Accordingly, the true scope of protection of the present invention should be determined only by the technical idea of the appended claims.

10:
20: first light transmitting portion
30: first broadcaster
31: First port
32: second port
33: Third port
40: second light transmitting portion
50: first optical element
60: Third light transmitting portion
70: Second broadcaster
71: First port
72: second port
73: Third port
80: Fourth light-
90: second optical element
100: Pump light output section
110: fifth optical transmission portion
120:

Claims (8)

A broadband light source for outputting a reference light having a wide wavelength range;
A first optical transmission unit for transmitting the reference light output from the wideband light source unit;
A first port connected to the first light transmitting portion, receiving the reference light transmitted through the first light transmitting portion, outputting the received reference light to the second port, and outputting the first reflected light, which is input to the second port, A first optical circulator for outputting a signal to a port;
A second optical transmission unit for transmitting the reference light output from the second port of the first optical circulator;
A first optical element formed in the second optical transmission portion and selectively reflecting only light of a specific wavelength band from the plurality of wavelength bands included in the reference light passing through the second optical transmission portion toward the first optical circulator; Wow;
A third optical transmission unit that receives a first reflected light input to a second port of the first optical circulator and output to a third port of the first optical circulator;
A first port connected to the third optical transmission portion and configured to receive the first reflected light transmitted through the third optical transmission portion, to output the received first reflected light to the second port, A second optical circulator for outputting the reflected light to the third port;
A fourth optical transmission unit transmitting a first reflected light output from a second port of the second optical circulator;
And an output intensity of the pump light, which is formed in the fourth light transmitting portion and that is externally input to selectively reflect the light of the wavelength band corresponding to the first reflected light passing through the fourth light transmitting portion toward the second optical circulator, A second optical element whose refractive index is changed according to the refractive index;
A pump light output unit for adjusting the intensity of the pump light so as to vary a specific wavelength band reflected by the second optical device and outputting the adjusted intensity;
A fifth optical transmission unit that receives a second reflected light input to a second port of the second optical circulator and output to a third port of the second optical circulator;
And a light receiving unit for receiving the second reflected light transmitted through the fifth light transmitting unit,
And a judging unit for judging a wavelength band to be received by the light receiving unit,
The pump light output unit adjusts the intensity of the pump light according to an applied current value,
Wherein the judging unit judges the wavelength band of the second reflected light by using the current value applied to the pump light output unit at the time when the second reflected light is received by the light receiving unit. The optical fiber interrogator .
The method according to claim 1,
Wherein the first optical element comprises an optical fiber Bragg grating (FBG). ≪ Desc / Clms Page number 19 >
delete A broadband light source for outputting a reference light having a wide wavelength range;
A first optical transmission unit for transmitting the reference light output from the wideband light source unit;
A first port connected to the first light transmitting portion, receiving the reference light transmitted through the first light transmitting portion, outputting the received reference light to the second port, and outputting the first reflected light, which is input to the second port, A first optical circulator for outputting a signal to a port;
A second optical transmission unit for transmitting the reference light output from the second port of the first optical circulator;
A first optical element formed in the second optical transmission portion and selectively reflecting only light of a specific wavelength band from the plurality of wavelength bands included in the reference light passing through the second optical transmission portion toward the first optical circulator; Wow;
A third optical transmission unit that receives a first reflected light input to a second port of the first optical circulator and output to a third port of the first optical circulator;
A first port connected to the third optical transmission portion and configured to receive the first reflected light transmitted through the third optical transmission portion, to output the received first reflected light to the second port, A second optical circulator for outputting the reflected light to the third port;
A fourth optical transmission unit transmitting a first reflected light output from a second port of the second optical circulator;
And an output intensity of the pump light, which is formed in the fourth light transmitting portion and that is externally input to selectively reflect the light of the wavelength band corresponding to the first reflected light passing through the fourth light transmitting portion toward the second optical circulator, A second optical element whose refractive index is changed according to the refractive index;
A pump light output unit for adjusting the intensity of the pump light so as to vary a specific wavelength band reflected by the second optical device and outputting the adjusted intensity;
A fifth optical transmission unit that receives a second reflected light input to a second port of the second optical circulator and output to a third port of the second optical circulator;
And a light receiving unit for receiving the second reflected light transmitted through the fifth light transmitting unit,
Wherein the third optical transmission unit further comprises an optical amplifier for amplifying the first reflected light output from the third port of the first optical circulator.
A broadband light source for outputting a reference light having a wide wavelength range;
A first optical transmission unit for transmitting the reference light output from the wideband light source unit;
A first port connected to the first light transmitting portion, receiving the reference light transmitted through the first light transmitting portion, outputting the received reference light to the second port, and outputting the first reflected light, which is input to the second port, A first optical circulator for outputting a signal to a port;
A second optical transmission unit for transmitting the reference light output from the second port of the first optical circulator;
And a second optical transmission unit for receiving light of a predetermined wavelength band from the plurality of wavelength bands included in the reference light passing through the second optical transmission unit to selectively reflect the light of a specific wavelength band toward the first optical circulator, A first optical element whose refractive index is changed according to an output intensity of the pump light;
A pump light output unit for adjusting the intensity of the pump light toward the first optical device so as to vary a specific wavelength band reflected from the first optical device;
A third optical transmission unit that receives a first reflected light input to a second port of the first optical circulator and output to a third port of the first optical circulator;
A first port connected to the third optical transmission portion and configured to receive the first reflected light transmitted through the third optical transmission portion, to output the received first reflected light to the second port, A second optical circulator for outputting the reflected light to the third port;
A fourth optical transmission unit transmitting a first reflected light output from a second port of the second optical circulator;
A second optical element formed in the fourth optical transmission unit and selectively reflecting the light of a wavelength band corresponding to the first reflected light passing through the fourth optical transmission unit to the second optical circulator;
A fifth optical transmission unit that receives a second reflected light input to a second port of the second optical circulator and output to a third port of the second optical circulator;
And a light receiving unit for receiving the second reflected light transmitted through the fifth light transmitting unit,
And a judging unit for judging a wavelength band to be received by the light receiving unit,
The pump light output unit adjusts the intensity of the pump light according to an applied current value,
Wherein the judging unit judges the wavelength band of the second reflected light by using the current value applied to the pump light output unit at the time when the second reflected light is received by the light receiving unit. The optical fiber interrogator .
6. The method of claim 5,
Wherein the second optical device comprises a fiber Bragg grating (FBG). ≪ Desc / Clms Page number 20 >
delete A broadband light source for outputting a reference light having a wide wavelength range;
A first optical transmission unit for transmitting the reference light output from the wideband light source unit;
A first port connected to the first light transmitting portion, receiving the reference light transmitted through the first light transmitting portion, outputting the received reference light to the second port, and outputting the first reflected light, which is input to the second port, A first optical circulator for outputting a signal to a port;
A second optical transmission unit for transmitting the reference light output from the second port of the first optical circulator;
And a second optical transmission unit for receiving light of a predetermined wavelength band from the plurality of wavelength bands included in the reference light passing through the second optical transmission unit to selectively reflect the light of a specific wavelength band toward the first optical circulator, A first optical element whose refractive index is changed according to an output intensity of the pump light;
A pump light output unit for adjusting the intensity of the pump light toward the first optical device so as to vary a specific wavelength band reflected from the first optical device;
A third optical transmission unit that receives a first reflected light input to a second port of the first optical circulator and output to a third port of the first optical circulator;
A first port connected to the third optical transmission portion and configured to receive the first reflected light transmitted through the third optical transmission portion, to output the received first reflected light to the second port, A second optical circulator for outputting the reflected light to the third port;
A fourth optical transmission unit transmitting a first reflected light output from a second port of the second optical circulator;
A second optical element formed in the fourth optical transmission unit and selectively reflecting the light of a wavelength band corresponding to the first reflected light passing through the fourth optical transmission unit to the second optical circulator;
A fifth optical transmission unit that receives a second reflected light input to a second port of the second optical circulator and output to a third port of the second optical circulator;
And a light receiving unit for receiving the second reflected light transmitted through the fifth light transmitting unit,
Wherein the third optical transmission unit further comprises an optical amplifier for amplifying the first reflected light output from the third port of the first optical circulator.

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