KR101704731B1 - Optical current sensors with photonic crystal fibers and a method of its prodution - Google Patents

Abstract

The present invention relates to an optical current sensor using a photonic crystal optical fiber and a manufacturing method thereof, and more particularly, to an optical current sensor using a photonic crystal optical fiber using an optical fiber to detect a phase difference of light caused by a magnetic field so as to measure the intensity of a current flowing in a line. According to the present invention, the sensor comprises: an optical integrated circuit (IC) manufactured by being integrated on a substrate; and an optical fiber coil unit connected to the optical IC to convert a linear polarized light passing therethrough into a circular polarized light through a quadrant wavelength plate (QWP) installed on one side of a sensor head unit. Thus, since two factors, a QWP part and an optical sensing coil unit, increasing temperature dependency in the optical current sensor are improved, the temperature dependency of the optical current sensor is removed and thereby an optical current sensor having an identical response characteristic that does not change over a wide temperature range can be realized. Moreover, the QWP part is made by using the photonic crystal optical fiber instead of a basic polarization-maintaining (PM) optical fiber and the sensing coil unit is made by using a spun PM fiber which is made by rotating an optical axis instead of a normal optical fiber annealing method, so the temperature dependency of the sensor is reduced, correctness of the sensor is raised, and an application range of a tube current sensor can be widen due to a reduced manufacturing time and a high yield rate.

Description

TECHNICAL FIELD [0001] The present invention relates to a photocurrent sensor using a photonic crystal fiber and a manufacturing method thereof,

The present invention relates to a photocurrent sensor using a photonic crystal optical fiber for reducing temperature dependency and a manufacturing method thereof, and more particularly, to a photocurrent sensor using a photonic crystal fiber for measuring the intensity of light generated by a magnetic field The present invention relates to a photocurrent sensor using a photonic crystal optical fiber for detecting a difference and a manufacturing method thereof.

The photocurrent sensor has various advantages compared to the electric current measuring apparatus widely used in the past, and has received a great interest in the electric power industry at present. Various advantages include wide measurement range and high accuracy, possibility of measuring AC current of DC and high frequency, small size and light weight, high safety without risk of breakage due to surge current, Environment-friendly lighting without using gas and insulating oil. With the development of optical communication, along with the advancement of optical device technologies which have been widely developed, research results on various optical sensors are actively coming out.

The basic principle of the proposed photocurrent sensor is as follows. When the optical fiber is wrapped around the current-carrying wire, a fine refraction change occurs in the optical fiber due to the magnetic field induced from the current. This phenomenon is called the Faraday effect, and the change in the refractive index, which is proportional to the magnetic field strength, is confirmed by the change in polarization state of the light incident on the optical fiber. However, the polarization state change caused by the Faraday effect is very weak, and the polarization state of the light easily changes due to the change of characteristics of the optical fiber coil part which is wound around the wire according to changes in the external environment such as temperature and vibration.

In order to solve these problems, a polarization rotation reflection type photocurrent sensor using a polarization maintaining optical fiber has been proposed (Fiber-optic current sensor, US 2003/6636321 B2, October 21, 2003. Optical fiber electric current sensor and electric current measurement method , US 2010/0253320 A1, October 10, 2010.). In such a structure, when two perpendicularly polarized light beams are incident, the two-line polarized light in the optical fiber coil portion is converted into two kinds of circularly polarized light components rotating in different directions, and the two circularly polarized light have a phase difference due to the Faraday effect. Therefore, the current amount can be confirmed by measuring the phase difference of the two polarized lights at the output portion. The two polarized lights are reflected again through the optical fiber coil portion and pass through the same condensation, so that the phase difference generated on the path due to temperature or vibration is canceled out to disappear. The quarter wave plate (QWP) of the optical fiber coil part fabricated with the polarization maintaining optical fiber element that converts the linearly polarized light into the circularly polarized light is a factor that degrades the accuracy of the sensor due to the change of the characteristic according to the temperature change . In order to solve this problem, a method of canceling the two temperature dependencies of the QWP and the Faraday effect is used (Temperature-stabilized sensor coil and current sensor, US 2005/0088662 A1, published on April 28, 2005).

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a method of manufacturing a quartz waveguide (QWP) by replacing a PM optical fiber with a photonic crystal fiber, The purpose of this study is to solve the temperature dependent characteristics of polarization rotation type reflection type photocurrent sensor based on optical integrated circuit by using polarization maintaining fiber optic sensor coil manufactured by rotating.

According to an aspect of the present invention, there is provided an optical integrated circuit, which is an integrated optical device integrated on a substrate. And an optical fiber coil portion that converts linearly polarized light into circularly polarized light through a quarter wave plate (QWP) provided at one side of the sensor head portion, the linearly polarized light being connected to and passing through the optical integrated circuit, A photonic crystal fiber which lowers the temperature dependency can be used.

In the photocurrent sensor using the photonic crystal fiber, the optical integrated circuit may include an optical coupler, a phase modulator, a polarization converter, an optical interferometer, an optical power distributor, and a polarizer.

In the photocurrent sensor using the photonic crystal fiber, the quarter wave plate can be brought into contact with the optical axis of the photonic crystal fiber and the optical axis of the polarization maintaining optical fiber shifted by 45 degrees.

In the photocurrent sensor using the photonic crystal fiber, the linearly polarized light can be converted into the left circularly polarized light and the right circularly polarized light due to the quarter wave plate (QWP).

In the photocurrent sensor using the photonic crystal fiber, the left circularly polarized light and the right circularly polarized light pass through the optical fiber coil part, the phase delay is accumulated, and they are reflected by the mirror provided on the other side of the sensor head part and can be converted into linearly polarized light.

According to an aspect of the present invention, there is provided a method of manufacturing a photonic crystal optical fiber, comprising: a bonding step of contacting an optical axis of a photonic crystal optical fiber and an optical axis of a polarization maintaining optical fiber such that the optical axis is shifted by 45 degrees; And cutting the photonic crystal optical fiber according to a position where the length of the photonic crystal fiber reaches a difference in phase by a quarter wavelength; And attaching a polarization maintaining optical fiber fabricated by rotating an optical axis, which is another optical fiber used as a sensing coil, at a cut position after the cutting step; A photonic crystal optical fiber that changes linearly polarized light to circularly polarized light to lower the temperature dependency can be used.

In the method of manufacturing such a photonic crystal optical fiber, the optical axis of the photonic crystal optical fiber and the optical axis of the polarization maintaining optical fiber are shifted by 45 占 so that linearly polarized light can be changed to circularly polarized light.

According to the photocurrent sensor using the photonic crystal fiber and the manufacturing method thereof, the temperature dependency of the photocurrent sensor is solved by improving the QWP component and the optical fiber sensing coil, which are two factors that increase the temperature dependency in the photocurrent sensor, A photocurrent sensor having the same response characteristics without changing its characteristics can be realized.

In place of the basic polarization maintaining optical fiber, a QWP part is fabricated using a photonic crystal optical fiber, and a sensing coil part is fabricated by using a spun PM fiber fabricated by rotating an optical axis instead of annealing a general optical fiber By improving the temperature dependence of the sensor, increasing the accuracy of the sensor, shortening the manufacturing time and achieving high yield, the scope of the photocurrent sensor can be widened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an integrated photocurrent sensor comprising an optical fiber coil part and an optical waveguide device for optical signal processing according to a preferred embodiment of the present invention; FIG.
FIG. 2 (a) is a graph illustrating a relationship between a temperature of a photocurrent sensor using a photonic crystal fiber according to a preferred embodiment of the present invention and a quaternary wavelength plate A change in phase difference at the time when the phase difference is changed;
FIG. 2 (b) is a graph illustrating a change in the size of a sensor output signal detected by a photodetector due to a phase delay error of a quarter wavelength plate according to a temperature change of a photocurrent sensor using a photonic crystal fiber according to a preferred embodiment of the present invention. A drawing;
FIG. 3 is a view illustrating a step of fabricating a quarter wave plate using a polarization maintaining optical fiber according to a preferred embodiment of the present invention; FIG.
FIG. 4 illustrates a quarter wave plate configuration according to a preferred embodiment of the present invention; FIG.
5 is a flowchart illustrating a process of manufacturing an integrated optical device based on a polymer optical waveguide according to a preferred embodiment of the present invention;
6 is a graph showing the relationship between the output signal magnitudes due to the phase delay error due to the temperature change of each quarter wavelength plate 210 made of the photonic crystal polarization maintaining optical fiber and the panda type polarization maintaining optical fiber according to the preferred embodiment of the present invention FIG.
FIG. 7 is a graph comparing temperature dependency of PMF-QWP, an annealed fiber coil, a PCF-QWP, and an integrated photocurrent sensor composed of a spun PM fiber according to a preferred embodiment of the present invention;
8 is a diagram illustrating output characteristics of an integrated photocurrent sensor fabricated using a PCF-QWP and a spun PM fiber according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 8. FIG. On the other hand, those skilled in the art to which the present invention applies, such as related arts for bonding the respective optical fibers, related arts for connecting optical fibers and optical fibers, and program-related technologies for measuring temperature dependency, The details of the present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a block diagram of an integrated photocurrent sensor comprising an optical fiber coil part according to a preferred embodiment of the present invention and an optical waveguide device for optical signal processing; FIG.

Referring to FIG. 1, a photocurrent sensor using a photonic crystal fiber is composed of an optical integrated circuit and an optical fiber coil portion.

A photocurrent sensor using such a photonic crystal fiber is provided with an optical integrated circuit, which is an integrated optical device manufactured by being integrated on a substrate. A linearly polarized light beam, which is connected to and passes through the optical integrated circuit, is composed of an optical fiber coil part converted into circularly polarized light through a quarter wave plate (QWP) provided on one side of the sensor head part, Use optical fiber.

Polarization rotation reflection type photocurrent sensor has stability against external disturbance (temperature, vibration) by compensating initial phase difference between two vertical polarized light. A structure of a polarization rotation type reflection type photocurrent sensor to which a photonic crystal polarization maintaining optical fiber is applied is shown in Fig.

The optical integrated circuit includes an optical coupler 180, a phase modulator 120, a polarization converter 160, an optical interferometer 140, an optical power splitter 170, a polarizer 150, and the like. The basic operation principle of the photocurrent sensor is as follows. The 45-degree linearly polarized light output from the SLED light source 100 is split into the fast and slow axis components of the PM fiber after passing through the integrated optical device.

A quarter wave plate (QWP) 210 made of photonic crystal fiber (PCF) aligned by rotating the optical axis by 45 ° is located at the front side of the sensor head part (Sensor head part). Due to the quarter wave plate 210, the linearly polarized light of the two fast and slow axis components is converted into Left-Handed Circular Polarization (LHCP) and Right-Handed Circular Polarization (RHCP), respectively. The phase lag is accumulated due to the Faraday effect in the two circularly polarized lights that communicate with the optical fiber coil 200. [ After being reflected by the mirror 220, the two circularly polarized lights are converted into the linearly polarized light while communicating with the optical fiber coil 200 and the quarter wave plate 210 in the opposite direction. At this time, the linearly polarized light of the fast axis component is converted into the linearly polarized light of the slow axis component upon input, and returned to the polarization maintaining optical fiber again.

Therefore, the phase difference between the fast axis component and the slow axis component generated while passing through the polarization maintaining optical fiber when input into the optical fiber coil portion is canceled in the opposite direction. The two polarized light returned with the phase information delayed by the Faraday effect are incident on the integrated optic device again through the polarization maintaining optical fiber. Due to the optical power splitter 170, the two linearly polarized lights are incident on the upper branch and the lower branch in half-halves. The two-line polarized light inputted into the lower branch is converted into the TE component by the polarization converter 160 and the TM component by the polarization converter 160 into the TE component. The TE component thus converted exhibits an interference phenomenon at the splint 140. The TM components traveling through the two branches are absorbed by the polarizer 150 using a metal thin film and do not affect the interferometer. the phase modulator 120 located in the upper branch will maintain the initial phase difference of the two interfering TE components after correction. The two TE components are input to the photodetector 110 after experiencing an interference phenomenon in the optical coupler 180.

FIG. 2 (a) is a graph illustrating a relationship between a temperature of a photocurrent sensor using a photonic crystal fiber according to a preferred embodiment of the present invention and a quaternary wavelength plate In the case of the first embodiment of the present invention. FIG. 2 (b) is a graph illustrating a change in the size of a sensor output signal detected by a photodetector due to a phase delay error of a quarter wavelength plate according to a temperature change of a photocurrent sensor using a photonic crystal fiber according to a preferred embodiment of the present invention. Fig.

During the operation of the photocurrent sensor, the integrated optical device is placed in a controlled environment, but since the optical fiber coil portion is exposed to the external environment, it is very important to eliminate the temperature dependency of the optical fiber coil portion. Also, the portion of the optical fiber coil portion that is most sensitive to temperature is the quarter wave plate 210. The response of the photocurrent sensor according to the temperature sensitivity effect of the quarter wave plate 210 was calculated using the Jones matrix. The polarization of the reflected signal can be expressed as follows.

(1)

(One)

(2)

(2)

(3)

(3)

,

그리고

는 사분의 일 파장판(210), 패러데이 로테이터, 그리고 리플렉터를 존스 메트릭스로 나타낸 것이다.

와

는

와

의 역행렬이고 역방향에 대해 존스 메트릭스이다.

는 전류로 인해 유도된 패러데이 효과에 의해 발생된 위상지연이다. δ는 사분의 일 파장판(210)의 온도변화로 인해 발생된 지연 에러이다. 45°회전된 선편광의 입력편광에 대해, 출력편광의 fast and slow axis 성분 간 위상차는

로 나타낸다.[참고 문헌: G. Frosio, and R. Dandliker, "Reciprocal reflection interferometer for a fiber-optic Faraday current sensor," Appl. Optics, 33(25), 6111-6122 (1994)]

,

And

A quarter wave plate 210, a Faraday rotator, and a reflector in a Jones matrix.

Wow

The

Wow

And is a Jones matrix for the reverse direction.

Is the phase delay caused by the Faraday effect induced by the current. and delta is the delay error caused by the temperature change of the quarter wave plate 210. [ For the input polarized light of the 45 ° rotated linearly polarized light, the phase difference between the fast and slow axis components of the output polarized light is

[References: G. Frosio, and R. Dandliker, "Reciprocal reflection interferometer for a fiber-optic Faraday current sensor," Appl. Optics, 33 (25), 6111-6122 (1994)]

(4)

(4)

(5)

(5)

의 변화는 도2(a)에서 보여진다. 근사화된 출력 위상 지역 값은 δ값이 커질수록 증가한다. 판다 타입(Panda type)편광 유지 광섬유가 사분의 일 파장판(210)으로 사용될때, ΔT=100℃에 대해 δ눈 9.38°이고 계산에 사용된 판다 타입 편광유지 광섬유의 온도에 따른 복굴절 변화 값은

이다.
As the value of? increases

Is shown in Fig. 2 (a). The approximated output phase region values increase as the value of δ increases. When the Panda type polarization maintaining optical fiber is used as the quarter wave plate 210, the birefringence change value according to the temperature of the panda type polarization maintaining optical fiber used in the calculation is?

to be.

[참고문헌: P. Ma, N. Soung, J. Jin, J. Soung, X. Xu, “Birefringence sensitivity to temperature of polarization maintaining photonic crystal fibers,” Optics & Laser Technol., 44(6), 1829?1833 (2012).]를 가지고 ΔT=100℃에 대해 δ는 0.28°이다.
On the other hand, photonic crystal fiber

Optics & Laser Technol., 44 (6), 1829 (1986). [References] P. Ma, N. Soung, J. Jin, J. Soung, X. Xu, "Birefringence sensitivity to temperature- 1833 (2012).) And for delta T = 100 deg. C, delta is 0.28 deg.

The mirror 220 is attached to the end of the quarter wave plate 210 before being connected to the optical fiber coil 200 in order to confirm the temperature dependence of only the quarter wave plate 210 . The integrated fluorescent device is connected to the quarter wave plate 210. In this configuration, the phase modulator 120 is operated to obtain an interference signal generated due to? Of the quarter wave plate 210.

(7)

(7)

(8)

(8)

(9)

(9)

(10)

(10)

,

그리고

는 편광기(150), 위상변조기(120) 그리고 반 파장판을 존스 메트릭스로 나타낸 것이다.

는 위상변조시(120)로 인해 발생하는 위상 변화이다.

를 가지는 입력신호에 대해, 광전류센서의 최종 출력 신호는 다음과 같다.

,

And

A polarizer 150, a phase modulator 120, and a half-wave plate as a Jones matrix.

Is a phase change that occurs due to phase modulation 120.

The final output signal of the photocurrent sensor is as follows.

(11)

(11)

항은 SLED 광원(100)의 제한된 코히어런스로 인해 갑섭현상이 발생하지 않는 성분이다.

은 최대 출력신호를 만들기 위해 정확히 바이어스 될 때 신호의 크기는 도 2(b)와 같이 δ값에 의존한다. 따라서 온도에 의존하는 δ의 변화는 출력 신호의 크기 변화로 부터 확인된다.
In this formula

Is a component that does not cause a collapse due to the limited coherence of the SLED light source 100.

Is exactly biased to produce the maximum output signal, the magnitude of the signal depends on the value of delta as shown in Figure 2 (b). Therefore, the change of the temperature-dependent delta is confirmed from the change in the magnitude of the output signal.

FIG. 3 is a view illustrating a quarter wavelength plate manufacturing process using a polarization maintaining optical fiber according to a preferred embodiment of the present invention.

In order to compare the temperature dependency, two kinds of quarter wave plates 210 were fabricated by using Panda type polarization maintaining optical fiber (PMF) and photonic crystal polarization maintaining optical fiber (PCF), respectively. The quarter wave plate 210 is attached at an angle of 45 degrees to the optical axis of the polarization maintaining optical fiber as shown in FIG. The polarization maintaining optical fiber or the photonic crystal polarization maintaining optical fiber is cut to the exact length of the PM fiber to generate the half-wave phase retardation. The short-length single mode optical fiber is then attached to create the same effect of attaching the optical fiber coil 200. The length of the quarter wave plate 210 calculated from the birefringence is 0.92 mm and 1.00 mm for PMF-QWP and PCF-QWP, respectively. The performance of the quarter wave plate 210 is evaluated by measuring the polarization extinction ratio of the output light with respect to the linear input polarization. The stress is relaxed by the arc junction so that the length of the quarter wave plate 210 deviates from the design. PCF-QWP and PMF-QWP having lengths of 1.25 mm and 0.90 mm among the samples of the quartz wave plate 210 having different lengths exhibit the highest output polarization extinction ratio. The phase delay error of the two samples is only 2.0 to 2.6 degrees. The PCF-QWP has a length close to the design value because only one-third of the arc power applied to the PMF-QWP is applied to prevent air-hole breakage by the arc.

4 is a view illustrating a quarter wavelength plate configuration according to a preferred embodiment of the present invention.

4, a quarter wave plate (a) is composed of (a) a panda type polarization maintaining optical fiber (PMF) and a photonic crystal optical fiber, and (b) a photonic crystal fiber (PCF) FIG. (C) PMF, (d) PCF, and (e) spun PM fiber. Figure 4 shows the junction between PCF-QWP and PM fiber.

FIG. 5 is a flowchart illustrating a manufacturing process of an integrated optical device based on a polymer optical waveguide according to a preferred embodiment of the present invention.

이며 구조는 inverted rib이다. 표면 플라즈몬 흡수를 통해 TM 편광을 흡수하는 TE-pass polarizer를 삽입하기 위해 1.8 ㎛의 두께를 가지는 첫 번째 상부 클래딩 위에 길이 9 mm의 Cr-Au 금속 패턴을 제작한다. 두 번째 상부 클래딩 형성 이후 가열 전극은 광학 효과를 이용한 위상변조기로 제작된다. 이후 20 ㎛의 두께를 가지는 폴리이미드 반파장판을 삽입하기 위해 groove line은 다이싱 소우를 사용하여 형성한다. 이후 반파장판을 groove line에 삽입하고 UV 경화용 에폭시를 사용하여 고정 시킨다.
Referring to FIG. 5, the integrated optical device used for making an interference signal proportional to the Faraday effect is manufactured based on a well-established polymer optical waveguide technique. Fluorine-substituted low loss polymers supplied by Chem Optics are used to form core and cladding layers with refractive indices of 1.440 and 1.430, respectively. The core size of the optical waveguide is 6.0 x 5.8

And the structure is inverted rib. To insert a TE-pass polarizer that absorbs TM polarized light through surface plasmon absorption, a 9-mm long Cr-Au metal pattern is fabricated on the first upper cladding with a thickness of 1.8 μm. After forming the second upper cladding, the heating electrode is fabricated with a phase modulator using an optical effect. A groove line is then formed using a dicing saw to insert a polyimide half-wave plate having a thickness of 20 μm. The half-wave plate is then inserted into the groove line and fixed with UV curing epoxy.

6 is a graph showing the relationship between the output signal magnitudes due to the phase delay error due to the temperature change of each quarter wavelength plate 210 made of the photonic crystal polarization maintaining optical fiber and the panda type polarization maintaining optical fiber according to the preferred embodiment of the present invention FIG. 7 is a graph comparing the temperature dependency of the PMF-QWP, the annealed fiber coil, the PCF-QWP and the spun PM fiber according to the preferred embodiment of the present invention. 8 is a diagram illustrating output characteristics of an integrated photocurrent sensor fabricated using a PCF-QWP and a spun PM fiber according to a preferred embodiment of the present invention.

In order to measure the temperature dependence of the quarter wave plate 210, the optical fiber mirror 220 is attached to the end of the single mode optical fiber and the PM fiber is bonded to the integrated optical device. The phase delay error of the quarter wave plate 210 can be evaluated by applying the modulation signal in the phase modulator 120 as described above. The mirror 220 and attached quarter wave plate 210 are positioned in a temperature controlled oven and the magnitude of the output signal is measured as shown in FIG. 6 while changing the temperature to 25-80 ° C.

The PMF-QWP exhibited an amplitude change of 1.8% of the output signal, and the change in birefringence with temperature was 0.085 ° / ° C, which was close to 0.098 ° / ° C as the design result. For PCF-QWP, the amplitude of the output signal is limited to within ± 0.3% during temperature changes due to the birefringence change due to the low temperature of 0.003 ° / ° C of PCF.

In order to complete the sensor head subassembly, the two quarter wave plates 210 are bonded to the respective optical fiber coil 200 and attached to the mirror 220 at the other end. The PCF-spun fiber sensor with PCF-QWP and HI-BI spun fiber and the PMF-annealed fiber sensor with PMF-QWP and annealed fiber coil were used for temperature dependence experiments. The PMF-QWP is bonded to the heat-treated fiber-optic coil as a reference sensor while the PCF-QWP is bonded to the fiber-optic coil fabricated from a Hi-Bi spun fiber with a circular beat length (@ 1550 nm) of 72 mm and a spin spacing of 4.8 mm do.

이다 [참고 문헌: K. Bohnert, P. Gabus, J. Nehring, and H. Brandle, “Temperature and vibration insensitive fiber-optic current sensor,” J. Lightwave Technol. 20(2), 267-276 (2002)]. 의존성의 나머지는 PCF-QWP의 위상 지연 오차와 열처리된 광섬유 코일의 잔여 복굴절에 의해 나타난다. PCF-spun fiber sensor는 78°C 까지 온도를 증가 시키더라도 ±1% 이내에서 신호 변화 나타나는 것을 알 수 있고 이 변화는 PMF-annealed fiber sensor의 1/7정도로 작게 나타남을 볼 수 있다.
The diameter of the optical fiber coil used to confirm the temperature dependency was 90 mm and the optical fiber was wound 10.5 turns. The sensor head is placed in an oven that controls the temperature of the body through which the 480 Arms current flows through the fiber optic coil. The sensor signal amplitude for temperature changes above 70 ° C appears as in Fig. The PMF-annealed fiber sensor exhibits a 7.60% output signal amplitude change, of which 0.35% is due to a change in the Verdet constant. The temperature dependent coefficient of the Verdet constant is

K. Bohnert, P. Gabus, J. Nehring, and H. Brandle, "Temperature and vibration insensitive fiber-optic current sensor," J. Lightwave Technol. 20 (2), 267-276 (2002)]. The remainder of the dependence is due to the phase retardation error of PCF-QWP and the residual birefringence of the annealed fiber optic coil. It can be seen that the PCF-spun fiber sensor shows signal changes within ± 1% even when the temperature is increased to 78 ° C, which is smaller than 1/7 of the PMF-annealed fiber sensor.

A PCF-spun fiber sensor was fabricated using an optical fiber coil (5.5 turns) with a diameter of 1160 mm to install a photocurrent sensor surrounding the large-diameter conductor. The toroidal type current loop was used to amplify the magnetic field and the sensor signal according to the applied current in the range of 500 Arms to 12 kArms was measured as shown in FIG. Two points of black and blank points are measured at increasing and decreasing applied currents. The relative error of the output of the sensor according to the applied current is within ± 0.1%, and this result satisfies the presentation condition based on 0.5 accuracy class (IEC 60044-8).

According to the photocurrent sensor using the photonic crystal fiber and the manufacturing method thereof, the temperature dependency of the photocurrent sensor is solved by improving the QWP component and the optical fiber sensing coil, which are two factors that increase the temperature dependency in the photocurrent sensor, A photocurrent sensor having the same response characteristics without changing its characteristics can be realized.

In place of the basic polarization maintaining optical fiber, a QWP part is fabricated using a photonic crystal optical fiber, and a sensing coil part is fabricated by using a spun PM fiber fabricated by rotating an optical axis instead of annealing a general optical fiber The temperature dependence of the sensor can be improved, the accuracy of the sensor can be improved, the manufacturing time can be shortened and the yield of the tube current sensor can be widened due to the high yield.

Although the photocurrent sensor using the photonic crystal fiber according to the preferred embodiment of the present invention and the method of fabricating the photocurrent sensor according to the present invention have been described above with reference to the drawings and the drawings, the present invention is merely illustrative and not limitative of the present invention. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention.

100: light source 110: photodetector
120: phase modulator 130: polymer optical waveguide
140: optical interferometer 150: polarizer
160: polarization converter 170: optical power splitter
180: optical coupler 190: polarization maintaining optical fiber
200: Optical fiber coil 210: Quarter wavelength plate
220: mirror 230: wire

Claims (5)

An optical integrated circuit integrated on a substrate and fabricated by integration; And
And an optical fiber coil part which is converted into circularly polarized light through a quarter wave plate (QWP) provided on one side of the sensor head part,
Wherein the photonic crystal fiber is a photonic crystal fiber that changes the linearly polarized light to the circularly polarized light to lower the temperature dependency.
The method according to claim 1,
Wherein the optical integrated circuit comprises a photonic crystal fiber comprising a photocoupler, a phase modulator, a polarization converter, an optical interferometer, an optical power splitter, and a polarizer.
The method according to claim 1,
Wherein the quarter wave plate is in contact with the optical axis of the photonic crystal optical fiber so that the optical axis of the polarization maintaining optical fiber is shifted by 45 占.
A splicing step of making the optical axis of the photonic crystal optical fiber and the optical axis of the polarization maintaining optical fiber are shifted by 45 占; Wow
A cutting step of cutting the photonic crystal optical fiber according to a position where the length of the photonic crystal fiber reaches a difference in phase by a quarter wavelength; And
Attaching a polarization maintaining optical fiber fabricated by rotating an optical axis which is another optical fiber used as a sensing coil at a cut position after the cutting step; Including,
Wherein the photonic crystal fiber is a photonic crystal fiber that changes linearly polarized light to circularly polarized light to lower the temperature dependency.
5. The method of claim 4,
Wherein the optical axis of the photonic crystal fiber and the optical axis of the polarization maintaining optical fiber are shifted by 45 占 to change the linearly polarized light to circularly polarized light.

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