KR101670287B1 - wavelength variable optical filter and optical sensor system using the same - Google Patents

Abstract

According to an aspect of the present invention, there is provided a wavelength tunable optical filter and an optical sensor system using the tunable optical filter, the optical tunable optical filter including a core layer, a wavelength adjusting section capable of adjusting wavelengths of light transmitted or reflected by the core layer, An electric pulse generating unit connected to the optical waveguide so as to apply a pulse potential to the optical waveguide; and an electric pulse generating unit configured to generate the electric pulse, And a control section for controlling the driving of the electric pulse generating section so that the pulse potential is applied for a first time period, wherein the first time is a period during which the wavelength of the light transmitted or reflected by the wavelength adjusting section changes during the first time, And the reaction time before the state of change to the stable state at the refractive index corresponding to the applied electric potential is applied. According to the wavelength tunable optical filter and the optical sensor system using the tunable optical filter, the wavelength can be varied by using the linear wavelength tuning characteristic during the reaction time, which is an inherent characteristic of the electro-optical material.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength tunable optical filter using an optical pulse response characteristic,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunable optical filter and an optical sensor system using the tunable optical filter. More particularly, the present invention relates to a tunable optical filter capable of varying a wavelength using a change in refractive index during an electrical pulse response time And an optical sensor system using the same.

Optical sensors such as fiber gratings, which change the sensor signal in the wavelength range, require a very high level of wavelength accuracy up to 1 pm, so expensive complex wavelength tunable light sources are used in sensor systems.

Such a wavelength variable light source is variously disclosed in Korean Patent Laid-Open No. 10-2011-0070305.

The sensor system has developed to be able to operate as many sensors as possible with about 100 sensors.

On the other hand, sensor demand for power equipment such as protection relays, switchgear, and gas energy fields such as gas storage and piping is increasing. In these fields, optical sensor systems that operate small number of 10 sensors are needed. However, existing devices are expensive and difficult to apply to the field.

SUMMARY OF THE INVENTION The present invention has been devised to solve the problems described above, and it is an object of the present invention to provide a wavelength conversion device capable of generating light having a variable wavelength using a change in refractive index during a reaction time from an electro- A variable optical filter, and an optical sensor system using the variable optical filter.

According to an aspect of the present invention, there is provided a wavelength tunable optical filter including a core layer, a wavelength adjusting section capable of adjusting a wavelength of light transmitted or reflected by the core layer, And a cladding formed of an electrooptic material whose refractive index changes according to the applied electric energy; An electric pulse generator connected to the optical waveguide so as to apply a pulse potential to the optical waveguide; And a controller for controlling the driving of the electric pulse generator so that the pulse potential is applied for a first time set by the electric pulse generator, wherein the first time is a time when the wavelength of the light transmitted or reflected by the wavelength adjuster The reaction time until the electro-optical material forming the clad is changed to the stable state at the refractive index corresponding to the applied electric potential is applied so as to be varied during the first time.

According to an aspect of the present invention, an optical fiber grating formed on the core layer is applied to the wavelength adjusting section of the optical waveguide.

According to still another aspect of the present invention, the wavelength adjuster of the optical waveguide is formed of a pulsed orbital spaced apart from the core layer by 180 to 220 占 퐉 and has a diameter of 10 to 20 占 퐉.

Preferably, the electro-optical material forming the clad is at least one selected from the group consisting of poly-methylmethacrylate (PMMA), α-methylstyrene-co-maleic anhydride (Poly MSMA), P2ANS, KH2PO4, NH4H2PO4, LiTaO3, Ti: LiNbO3 and LiNbO3 do.

Also, the first time is 1 ns to 5 ms.

According to another aspect of the present invention, there is provided a sensor system including a core layer, a wavelength adjusting unit adapted to adjust a wavelength of light transmitted or reflected by the core layer, And a cladding formed of an electrooptic material whose refractive index changes according to the applied electric energy; A light source for introducing light into the core layer; An electric pulse generator connected to the optical waveguide so as to apply a pulse potential to the optical waveguide; A light distribution unit that receives light transmitted through or reflected by the wavelength adjusting unit and distributes the light to a plurality of distribution channels; Optical fiber grating sensors corresponding to the distribution channels of the optical distributor; A detection optical coupler connected to each of the distribution channels of the optical distributor and transmitting the incident light to the optical fiber grating sensor and outputting a signal traveling backward from the optical fiber grating sensor to a detection end; A photodetector for detecting a signal received from a detection terminal of each of the optical couplers for detection; And a controller for controlling the driving of the electric pulse generator so that the pulse potential is applied for a first time set by the electric pulse generator and processing a signal received by the optical detector, A reaction time until a stable state is obtained with a refractive index corresponding to a potential applied to the electrooptic material forming the clad is changed so that the wavelength of light transmitted or reflected by the adjusting unit varies during the first time.

According to an aspect of the present invention, an optical fiber grating formed on the core layer is applied to the wavelength adjuster of the optical waveguide, the light splitting unit causes the light emitted from the light source to enter the core layer, An optical circulator for outputting light traveling in a reverse direction to a main output terminal; And a distribution optical coupler for distributing the light output from the main output terminal of the optical circulator to each of the distribution channels.

According to the wavelength tunable optical filter and the optical sensor system using the wavelength tunable optical filter according to the present invention, the wavelength can be varied by using the linear wavelength tuning characteristic during the reaction time, which is an inherent characteristic of the electro-optical material, do. In addition, since it is possible to eliminate the inconvenience of using a wavelength locker that provides a reference wavelength in existing equipment in which wavelength offset occurs, and since there is no need for a separate device to secure wavelength accuracy, It is possible to simplify the manufacturing process. In addition, since the existing equipment is expensive, it is limited to applications where about 100 sensors can be utilized. However, since the present invention can be applied to small-sized sensor applications of less than 10, the application field is expanded.

1 is a view showing a wavelength tunable optical filter according to an embodiment of the present invention,
2 is a plan view of a light waveguide according to another embodiment of the present invention,
3 is a cross-sectional view of the optical waveguide of FIG. 2,
4 is a view showing a sensor system to which a wavelength tunable filter according to the present invention is applied.

Hereinafter, a wavelength tunable optical filter according to a preferred embodiment of the present invention and an optical sensor system using the same will be described in detail with reference to the accompanying drawings.

1 is a view showing a wavelength tunable optical filter according to an embodiment of the present invention.

Referring to FIG. 1, a tunable optical filter 100 according to the present invention includes a light waveguide 110, an electric pulse generator 130, and a controller 150.

The optical waveguide 110 includes a core layer 112 and an optical fiber grating 121 formed in a partial region of the core layer 112 as a wavelength adjusting section capable of adjusting the wavelength of light reflected on the light incident on the core layer 112 And a clad 116 surrounding the region corresponding to the optical fiber grating 121 and formed of an electrooptic material whose refractive index is changed according to the applied electric energy.

The optical waveguide 110 reflects light of a specific wavelength determined by the optical fiber grating 121 with respect to light incident through the core 112, and the wavelength of the reflected light is varied by changes in temperature, refractive index, and the like.

As another example of the optical waveguide, the structure shown in Figs. 2 and 3 can be applied.

2 and 3, the optical waveguide 210 includes a core layer 112 which surrounds the waveguide by the clad 116 and has a gap g of 180 to 220 μm and is formed into a pulsed orbit, A structure in which a microring 221 having a thickness of 10 to 20 占 퐉 is applied as a wavelength adjusting portion can be applied.

Here, the region corresponding to the microring 221 applied to the wavelength adjusting portion or the entire clad 116 is formed of an electro-optic material.

In this optical waveguide 210, the wavelength of the light transmitted by the microring 221 is determined.

On the other hand, a part of the clad 116 corresponding to the wavelength tuning region of the optical waveguide, or the electro-optical material applied to the entire clad 116, has a unique reaction time until it is stabilized corresponding to the potential applied with the refractive index a material having a response time and a refractive index linearly changing during a reaction time is applied.

Here, the reaction time refers to the time at which the refractive index changes until the refractive index gradually changes from the initial refractive index before the application of the potential to a stable refractive index value corresponding to the applied potential, before reaching a stable refractive index value with respect to the applied potential.

Preferably, the electro-optical material to be applied to the optical waveguide is one selected from the group consisting of PMMA (poly-methylmethacrylate), Poly MSMA (alpha-methylstyrene-co-maleic anhydride), P2ANS, KH2PO4, NH4H2PO4, LiTaO3, Ti: LiNbO3 and LiNbO3 do.

The electric pulse generating unit 130 is connected to the optical waveguide 110 and 210 so that a pulse potential can be applied to the optical waveguide 110 and 210 through a position corresponding to the wavelength adjusting unit.

The electric potential applied from the electric pulse generating unit 130 may be 1.8 to 2.2 volts.

The controller 150 controls the driving of the electric pulse generator 130 so that the pulse electric potential is applied for the first time set by the electric pulse generator 130.

Here, the first time is a potential applied to the electro-optical material forming the clad 116 such that the wavelength of the light reflected or transmitted by the wavelength adjusting unit to which the optical fiber grating 121 or the microring 221 is applied is varied during the first time The reaction time is changed to a stable state at a refractive index corresponding to the refractive index.

The first time may be applied in consideration of the characteristics of the electro-optical material at 1 ns to 5 ms.

According to such a tunable optical filter 100, when a pulse potential is applied to the optical waveguide 110 (210) for a first time set within the reaction time of the electro-optical material, light whose wavelength varies linearly with time Can be obtained.

Hereinafter, a sensor system to which the tunable optical filter 100 is applied will be described with reference to FIG. Elements that perform the same functions as those in the preceding figures are denoted by the same reference numerals.

4, the optical sensor system 300 includes a light source 310, an optical circulator 320, a light waveguide 110, a distribution optical coupler 330, a detection optical coupler 340, A light detector 360, an electric pulse generator 130, a controller 350,

In the following description, the optical waveguide 110 will be described in a case where a structure in which the optical fiber grating 121 of FIG. 1 is applied as a wavelength adjusting unit is applied.

The light source 310 applies a light source that emits broadband light.

As an example, the light source 310 has a wavelength width of 10 nm.

On / off driving of the light source 310 is controlled by the control unit 350, which will be described later.

The optical distributor is adapted to receive light transmitted through or reflected by the wavelength tuning section of the optical waveguide 110 to be distributed to a plurality of distribution channels. In the illustrated example, the optical circulator 320 and the distribution optical coupler (330) was applied.

The optical circulator 320 irradiates the light emitted from the light source 310 to the core layer 112 of the optical waveguide 110 and reflects the light reflected by the optical fiber grating 121 of the optical waveguide 110 To the distribution optical coupler 330, which will be described later, through the main output terminal.

The distribution optocoupler 330 distributes the light output from the main output of the optical circulator 320 to each of the distribution channels.

The distribution optical coupler 330 is preferably a 1x8 optical coupler having eight distribution channels.

The detecting optical couplers 340 are connected to each of the distribution channels of the distribution optical coupler 330 of the optical distributor and transmit the incident light to the corresponding optical fiber grating sensor 345 and the optical fiber grating sensor 345 To a detection end that leads to the photodetector unit 360.

It is preferable that a 1x2 optical coupler is applied to the optical coupler 340 for detection.

The optical fiber grating sensors 345 are connected to the first output end of the optical coupler 340 for detection and an optical fiber having an optical fiber grating is applied.

The photodetector 360 detects a signal received from each of the detection ends of the optical couplers 340 for detection and outputs an electrical signal corresponding to the detected signal to the controller 350.

The control unit 350 controls the driving of the electric pulse generating unit 130 so that the pulse electric potential is applied to the optical waveguide 110 for the first time set by the electric pulse generating unit 130, Signal.

The control unit 350 can be constructed so as to detect the temperature of the region where the fiber grating sensors 345 are installed, and the temperature detection method is known, and detailed description is omitted.

In addition, the control unit 350 displays the detection result through the display unit 370.

On the other hand, when the optical waveguide of FIG. 2 is applied, the optical circulator 320 may be omitted, and the light transmitted through the optical waveguide may be incident on the optical coupler for distribution 330.

Such a sensor system 300 can advantageously simplify the structure because the wavelength can be varied by using the linear wavelength tuning characteristic during the reaction time, which is a characteristic of the electro-optical material.

110, 210; Optical waveguide 130: Electric pulse generating unit
150, 350:

Claims (9)

A core layer; a wavelength adjusting unit adapted to adjust a wavelength of light transmitted or reflected by the core layer; and an electro-optical material surrounding the area corresponding to at least the wavelength adjusting unit and having a refractive index changed according to the applied electric energy, An optical waveguide having a cladding formed thereon;
An electric pulse generator connected to the optical waveguide so as to apply a pulse potential to the optical waveguide;
And a controller for controlling driving of the electric pulse generator so that the pulse electric potential is applied for a first time set by the electric pulse generator,
Wherein the first time is a time until the wavelength of the light transmitted or reflected by the wavelength adjuster changes during the first period of time until the electrooptic material forming the clad is changed to a stable state at a refractive index corresponding to the applied electric potential Wherein the time-varying optical filter is applied with time. The wavelength tunable optical filter according to claim 1, wherein the wavelength tuning section of the optical waveguide has an optical fiber grating formed on the core layer. 2. The wavelength tunable optical filter according to claim 1, wherein the wavelength tuning section of the optical waveguide is formed of a microwave ring having a diameter of 10 to 20 mu m, . 4. The electro-optical device according to claim 2 or 3, wherein the electro-optical material forming the clad is at least one selected from the group consisting of PMMA (poly-methylmethacrylate), Poly MSMA (alpha-methylstyrene-co- maleic anhydride), P2ANS, KH2PO4, NH4H2PO4, LiTaO3, Ti: LiNbO3 , And LiNbO3 are applied to the wavelength tunable optical filter. The tunable optical filter according to claim 1, wherein the first time is 1 ns to 5 ms. A core layer; a wavelength adjusting unit adapted to adjust a wavelength of light transmitted or reflected by the core layer; and an electro-optical material surrounding the area corresponding to at least the wavelength adjusting unit and having a refractive index changed according to the applied electric energy, An optical waveguide having a cladding formed thereon;
A light source for introducing light into the core layer;
An electric pulse generator connected to the optical waveguide so as to apply a pulse potential to the optical waveguide;
A light distribution unit that receives light transmitted through or reflected by the wavelength adjusting unit and distributes the light to a plurality of distribution channels;
Optical fiber grating sensors corresponding to the distribution channels of the optical distributor;
A detection optical coupler connected to each of the distribution channels of the optical distributor and transmitting the incident light to the optical fiber grating sensor and outputting a signal traveling backward from the optical fiber grating sensor to a detection end;
A photodetector for detecting a signal received from a detection terminal of each of the optical couplers for detection;
And a controller for controlling the driving of the electric pulse generator so that the pulse potential is applied for a first time set by the electric pulse generator and processing the signal received by the optical detector,
Wherein the first time is a time until the wavelength of the light transmitted or reflected by the wavelength adjuster changes during the first period of time until the electrooptic material forming the clad is changed to a stable state at a refractive index corresponding to the applied electric potential Time is applied to the optical sensor system. The optical fiber grating according to claim 6, wherein the wavelength adjuster of the optical waveguide is an optical fiber grating formed on the core layer,
The light-
A photocoupler for injecting light emitted from the light source into the core layer and outputting light propagating in a direction opposite to that of the light reflected from the optical fiber grating to a main output;
And a distribution optical coupler for distributing the light output from the main output terminal of the optical circulator to each of the distribution channels. 8. The electro-optical device according to claim 7, wherein the electro-optical material forming the clad is at least one selected from the group consisting of PMMA (poly-methylmethacrylate), Poly MSMA (alpha-methylstyrene-co- maleic anhydride), P2ANS, KH2PO4, NH4H2PO4, LiTaO3, Ti: LiNbO3, Wherein one of the first and second optical sensors is applied. The optical sensor system according to claim 6, wherein the first time is 1 ns to 5 ms.

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