KR100785046B1 - Wavelength spacing tunable multichannel filter based on superimposed chirped fiber bragg gratings - Google Patents

Wavelength spacing tunable multichannel filter based on superimposed chirped fiber bragg gratings Download PDF

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KR100785046B1
KR100785046B1 KR1020060066793A KR20060066793A KR100785046B1 KR 100785046 B1 KR100785046 B1 KR 100785046B1 KR 1020060066793 A KR1020060066793 A KR 1020060066793A KR 20060066793 A KR20060066793 A KR 20060066793A KR 100785046 B1 KR100785046 B1 KR 100785046B1
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chirp
optical fiber
fiber grating
superimposed
wavelength
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Korean (ko)
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한영근
이주한
이상배
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한국과학기술연구원
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1828—Diffraction gratings having means for producing variable diffraction
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0005—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being of the fibre type
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/27—Optical coupling means with polarisation selective and adjusting means
    • G02B6/2726—Optical coupling means with polarisation selective and adjusting means in or on light guides, e.g. polarisation means assembled in a light guide
    • G02B6/274—Optical coupling means with polarisation selective and adjusting means in or on light guides, e.g. polarisation means assembled in a light guide based on light guide birefringence, e.g. due to coupling between light guides
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
    • G02B6/29395—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device configurable, e.g. tunable or reconfigurable
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/011—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  in optical waveguides, not otherwise provided for in this subclass
    • G02F1/0115—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  in optical waveguides, not otherwise provided for in this subclass in optical fibres
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Light Control Or Optical Switches (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

A wavelength spacing tunable multichannel filter is provided to freely increase or decrease a channel width by symmetrically changing a chirp ratio of superimposed chirped fiber Bragg gratings. A wavelength spacing tunable multichannel filter includes a first chirped fiber Bragg grating and a second chirped fiber Bragg grating. The second chirped fiber Bragg grating is formed to be superimposed on the first chirped fiber Bragg grating with an offset length between them. The multichannel filter includes a sampling chirped fiber Bragg grating having multichannel properties. A chirp ratio of the multichannel filter is adjusted to be symmetrical in a horizontal direction by using one of a bending, temperature-adjusting, and straining processes.

Description

중첩된 첩 광섬유 격자 기반 파장 간격 가변형 다채널 필터{Wavelength Spacing Tunable Multichannel Filter Based On Superimposed Chirped Fiber Bragg Gratings}Wavelength spacing tunable multichannel filter based on superimposed chirped fiber bragg gratings

도 1은 본 발명의 실시예에 따른 중첩된 첩 광섬유 격자 기반 다채널 필터에 관한 구성도이다.1 is a block diagram of a superposed chirped optical fiber grating based multichannel filter according to an embodiment of the present invention.

도 2는 도 1의 중첩된 첩 광섬유 격자의 중앙을 중심으로 S-자 형태의 구부림을 인가하여 첩 비율을 증가시키는 실험예이다.FIG. 2 is an experimental example of increasing the chirp ratio by applying an S-shaped bend around the center of the superposed chirp optical fiber grating of FIG. 1.

도 3은 도 2의 실험예에 따라 첩 비율 증가에 따른 파장 간격 증가를 나타낸 결과도이다.FIG. 3 is a result diagram illustrating an increase in a wavelength interval according to an increase of a chirp ratio according to the experimental example of FIG. 2.

도 4는 도 2의 실험예에 따라 첩 비율 증가에 따른 채널 간격 증가를 나타낸 결과도이다.FIG. 4 is a result diagram illustrating an increase in channel spacing according to an increase of a chirp ratio according to the experimental example of FIG. 2.

도 5는 도 1의 중첩된 첩 광섬유 격자의 중앙을 중심으로 도 2와 반대 방향으로 S-자 형태의 구부림을 인가하여 첩 비율을 감소시키는 실험예이다.FIG. 5 is an experimental example of reducing the chirp ratio by applying an S-shaped bend in a direction opposite to that of FIG. 2 with respect to the center of the superposed chirp optical fiber grating of FIG. 1.

도 6은 도 5의 실험예에 따라 첩 비율 감소에 따른 파장 간격 감소를 나타낸 결과도이다.FIG. 6 is a result diagram showing a wavelength interval decrease according to a decrease of a chirp ratio according to the experimental example of FIG. 5.

도 7은 도 5의 실험예에 따라 첩 비율 감소에 따른 채널 간격 감소를 나타낸 결과도이다.FIG. 7 is a diagram illustrating a channel spacing decrease according to a reduction of a chirp ratio according to the experimental example of FIG. 5.

본 발명은 중첩된(superimposed) 첩 광섬유 격자 기반 파장 간격 가변형 다채널 필터에 관한 것으로서, 구체적으로는 두 개의 첩 광섬유 격자를 일정한 오프셋(offset) 길이만큼 간격을 두고 겹쳐서 다채널에서 공진파장을 얻을 수 있는 다채널 필터를 구현한 후, 첩 비율을 좌우 대칭적으로 변화시킴으로써 입력 편광 상태에 영향을 받지 않고 공진 파장이 변하지 않으면서 다채널의 파장 간격을 자유롭게 조절할 수 있는 중첩된(superimposed) 첩 광섬유 격자 기반 파장 간격 가변형 다채널 필터에 관한 것이다.BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superimposed chirp optical fiber grating based wavelength spacing variable multichannel filter. Specifically, two chirp optical fiber gratings can be overlapped by a certain offset length to obtain resonant wavelengths in multiple channels. After implementing a multichannel filter, a superimposed chirp fiber grating can freely adjust the wavelength spacing of the multichannels without being affected by the input polarization state by changing the chirp ratio symmetrically. The present invention relates to a variable wavelength spacing multichannel filter.

종래의 다채널 필터는 광섬유 격자 필터, Mach-Zehnder 간섭계, 도파로 격자(arrayed waveguide grating) 등이 있다. Conventional multichannel filters include optical fiber grating filters, Mach-Zehnder interferometers, arrayed waveguide gratings, and the like.

일반적인 광섬유 격자 필터의 경우에는 각각의 파장에 일치하는 여러 개의 격자들을 연결하여 다채널 필터를 구현하는 것으로 가격이 비싸고 파장 가변을 위해서는 각각의 격자 필터를 조절해야 하므로 어려움이 있다. 파장 위치는 각각의 격자 필터를 조절하여 변화시킬 수 있지만 채널 간격을 일정하게 조절하기도 어려우며 상품화할 경우에 부피가 커질 가능성이 있다.In the case of a general optical fiber grating filter, it is expensive to implement a multi-channel filter by connecting a plurality of gratings matching the respective wavelengths, and it is difficult because each grating filter has to be adjusted for the variable wavelength. The wavelength position can be changed by adjusting each grating filter, but it is difficult to adjust the channel spacing constantly, and the volume may be large when commercialized.

Mach-Zehnder 간섭계의 경우에는 위상 변화를 정확하게 일치시켜야 다채널 필터 특성을 가질 수 있는데 위상 변화를 일치하는 것이 외부 온도, 진동, 스트레 인 등의 변화에 아주 민감하게 반응하므로 성능을 안정화하기가 아주 어렵다는 단점을 가지고 있다. 또한, 파장 위치 및 채널 간격을 조절하기도 어렵다.In the case of Mach-Zehnder interferometer, it is necessary to match the phase change accurately in order to have multi-channel filter characteristics. Matching the phase change is very sensitive to changes in external temperature, vibration, strain, etc. It has the disadvantage of being difficult. It is also difficult to adjust the wavelength position and channel spacing.

도파로 격자를 이용하는 경우에는 각각의 도파로의 위상을 정확하게 맞추야 하며 원하는 채널을 선택하기가 어려우며 상품화하였을 경우 부피가 커진다는 단점이 있다. 온도에 따라서 파장 위치의 가변은 용이하나 채널 간격 조절은 어렵다. In the case of using the waveguide grating, it is necessary to accurately match the phase of each waveguide, it is difficult to select a desired channel, and when it is commercialized, there is a disadvantage that the volume becomes large. It is easy to change the wavelength position according to the temperature, but it is difficult to adjust the channel spacing.

상술한 종래의 다채널 필터는 모두 입력신호의 편광 변화에 민감하게 반응하기 때문에 편광 의존도 억제가 필요하다.Since all of the above-described conventional multichannel filters are sensitive to the polarization change of the input signal, it is necessary to suppress the polarization dependence.

상술한 문제점을 해결하기 위한 본 발명의 목적은 채널 간격이 용이하게 조절되는 가변 다채널 필터를 구현하는데 있다.An object of the present invention for solving the above problems is to implement a variable multi-channel filter that can be easily adjusted channel spacing.

또한, 본 발명의 목적은 공진 파장의 변화를 억제한 기능성 다채널 필터를 구현하는데 있다.In addition, an object of the present invention is to implement a functional multi-channel filter suppressing the change in the resonance wavelength.

본 발명의 다른 목적은 입력신호의 편광 상태 변화에 무관한 다채널 필터를 구현하는데 있다.Another object of the present invention is to implement a multi-channel filter irrespective of the change in polarization state of an input signal.

또한, 본 발명의 목적은 제작 단가가 저렴하고 부피가 적은 다채널 필터를 구현하는데 있다.In addition, an object of the present invention is to implement a multi-channel filter with a low manufacturing cost and a small volume.

상기 목적을 달성하기 위한 본 발명의 중첩된(superimposed) 첩 광섬유 격자 기반 파장 간격 가변형 다채널 필터는 제 1 첩 광섬유 격자; 및 상기 제 1 첩 광섬유 격자와 오프셋(offset) 길이만큼 간격을 두고 겹쳐지게 형성되는 제 2 첩 광섬유 격자를 포함하는 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터를 형성하며, 상기 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터의 첩 비율을 좌우 대칭되게 조절하여 파장 간격을 가변시키는 것을 특징으로 한다.The superimposed chirp optical fiber grating based wavelength spacing variable multichannel filter of the present invention for achieving the above object comprises a first chirp optical fiber grating; And a superimposed chirp optical fiber grating based multichannel filter including a second chirp optical fiber grating formed to overlap with the first chirp optical fiber grating at an offset length. ) The chirp ratio of the optical fiber grating-based multichannel filter is laterally symmetrical to vary the wavelength spacing.

한편, 상기 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터의 첩 비율이 증가됨에 따라 파장 간격은 증가하고, 상기 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터의 첩 비율이 감소됨에 따라 파장 간격은 감소하는 것을 특징으로 한다.Meanwhile, as the chirp ratio of the superimposed chirp optical fiber grating based multichannel filter increases, the wavelength spacing increases, and as the chirp ratio of the superimposed chirp optical fiber grating based multichannel filter decreases, the wavelength spacing increases. Is characterized by decreasing.

여기서, 상기 첩 비율의 조절 방법은 구부림, 온도 조절 및 스트레인(strain) 중 어느 하나의 방법인 것을 특징으로 한다.Here, the method of adjusting the chirp ratio is characterized in that any one of bending, temperature control and strain (strain).

여기서, 상기 중첩된(superimposed) 첩 광섬유 격자 기반 파장 간격 가변형 다채널 필터는 샘플링 첩 광섬유 격자 구조를 포함하는 것을 특징으로 한다.The superimposed chirp optical fiber grating based wavelength spacing variable multichannel filter may include a sampling chirp optical fiber grating structure.

또한, 상기 목적은 제 1 첩 광섬유 격자; 및 상기 제 1 첩 광섬유 격자와 오프셋(offset) 길이만큼 간격을 두고 겹쳐지게 형성되는 제 2 첩 광섬유 격자를 포함하는 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터에 의해서도 달성될 수 있다.In addition, the object is a first chirp optical fiber grating; And a superimposed chirp optical fiber grating based multichannel filter including a second chirp optical fiber grating formed to overlap with the first chirp optical fiber grating at an offset length.

여기서, 상기 오프셋(offset) 길이 간격이 길면 파장 간격이 줄어들고, 상기 오프셋 길이 간격이 짧으면 파장 간격이 증가하는 것을 특징으로 한다.Here, when the offset length interval is long, the wavelength interval is reduced, and when the offset length interval is short, the wavelength interval is increased.

한편, 상기 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터의 첩 비 율을 좌우 대칭되게 조절하여 파장 간격을 가변시키는 것을 특징으로 한다.On the other hand, it is characterized by varying the wavelength interval by adjusting the superposition ratio of the superimposed chirp optical fiber grid-based multi-channel filter symmetrically.

여기서, 상기 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터의 첩 비율이 증가됨에 따라 파장 간격은 증가하고, 상기 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터의 첩 비율이 감소됨에 따라 파장 간격은 감소하는 것을 특징으로 한다.Here, the wavelength interval increases as the chirp ratio of the superimposed chirp optical fiber grating based multichannel filter increases, and the wavelength interval increases as the chirp ratio of the superimposed chirp optical fiber grating based multichannel filter decreases. Is characterized by decreasing.

이하, 본 발명의 바람직한 실시예를 첨부한 도면을 참조하여 상세히 설명한다.Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

자외선 레이저에 광섬유 격자를 노출시키면 게르마늄(Ge)이 첨가된 광섬유 코어 부분의 굴절률이 변하게 된다. 광섬유 격자는 광섬유 코어 내에 규칙적인 굴절률 변화를 유도하여 제조하는 것으로 위상 정합 조건(λp=2Λneff, Λ=격자 주기, neff=유효 굴절률)을 만족하는 파장에서 반사가 일어나는 한 개의 공진 파장을 갖는 광섬유 필터이다. 첩(chirped) 광섬유 격자는 격자 주기가 일정하지 않고 일정한 비율로 변하는 것으로 일반적인 광섬유 격자보다 넓은 파장 대역을 갖는다. Exposing the optical fiber grating to the ultraviolet laser changes the refractive index of the optical fiber core portion to which germanium (Ge) is added. Fiber gratings are fabricated by inducing regular refractive index changes in the fiber core, and they produce a single resonant wavelength where reflection occurs at wavelengths that satisfy the phase matching conditions (λ p = 2Λn eff , Λ = lattice period, n eff = effective refractive index). It is an optical fiber filter having. Chirped fiber gratings have a wider wavelength band than regular fiber gratings, where the grating periods are not constant but vary at a constant rate.

도 1은 본 발명의 실시예에 따른 중첩된 첩 광섬유 격자 기반 다채널 필터에 관한 구성도이다.1 is a block diagram of a superposed chirped optical fiber grating based multichannel filter according to an embodiment of the present invention.

도 1을 참조하면, 두 개의 첩 광섬유 격자를 일정한 오프셋(offset) 길이(d) 만큼 간격을 두고 겹쳐서 제조하면 중첩된(superimposed) 첩 광섬유 격자를 제조할 수 있다. 여기서, 오프셋(offset) 길이는 임계적 의미가 있는 것은 아니고 간섭 현 상을 일으키기 위해 필요한 길이를 말하며, 초기 파장 간격을 결정하는 변수이다. 따라서, 오프셋(offset) 길이가 길수록 파장 간격이 줄어들고 오프셋(offset) 길이가 작을수록 파장 간격이 증가한다.Referring to FIG. 1, superimposed chirped optical fiber gratings may be manufactured by overlapping two chirped optical fiber gratings by a predetermined offset length d. Here, the offset length does not have a critical meaning, but refers to a length necessary to cause an interference phenomenon, and is a variable for determining an initial wavelength interval. Therefore, the longer the offset length, the smaller the wavelength gap, and the smaller the offset length, the larger the wavelength gap.

다시 설명하면, 첩 광섬유 격자는 일반 광섬유 격자와 달리 격자의 주기가 일정한 비율로 변하는데(이를, "첩 비율"이라 한다), 제 1 첩 광섬유 격자와 제 2 첩 광섬유 격자를 일정한 오프셋(offset) 길이(d)만큼 간격을 두고 겹쳐 제조하면 광신호의 간섭을 유도할 수 있으므로 다수의 광섬유 격자 기반 공진기들이 구성된 것처럼 보이는 다채널 필터를 구현할 수 있다. In other words, the chirp fiber grating has a constant rate of change in the periodicity of the grating, which is referred to as a "chirp ratio", unlike a normal fiber grating, which provides a constant offset between the first and second chirp fiber gratings. Overlapping by the length (d) can induce interference of the optical signal, thereby realizing a multi-channel filter that appears to be composed of a plurality of fiber grating-based resonators.

여기서, 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터는 샘플링 첩 광섬유 격자 구조를 포함한다. 샘플링 첩 광섬유 격자는 두 개의 격자가 중첩되어 있지 않고 광섬유 격자 굴절률 변화에 포락선 변조(envelop modulation)가 되어 있는 구조로써 다채널 특성을 갖는 광섬유 격자이다.Here, the superimposed chirp fiber grating based multichannel filter includes a sampling chirp fiber grating structure. The sampling chief optical fiber grating is an optical fiber grating having a multi-channel characteristic in which two gratings do not overlap and envelop modulation is performed on the optical fiber grating refractive index change.

이때, 파장 간격(Δλ)은 다음 수학식 1과 같이 표현할 수 있다.In this case, the wavelength interval Δλ may be expressed by Equation 1 below.

Figure 112006050788626-pat00001
Figure 112006050788626-pat00001

여기서, λp는 첩 광섬유 격자의 중심 파장, B0는 첩 광섬유 격자의 초기 파장 대역폭, Δλ0는 중첩된(superimposed) 첩 광섬유 격자에서 초기 파장 간격, t는 중첩된(superimposed) 첩 광섬유 격자를 부착한 외팔보(cantilever beam)의 두께, L은 외팔보(cantilever beam)의 길이, ρe는 광탄성(photoelastic) 상수를 나타낸다.Where λ p is the center wavelength of the chirp fiber grating, B 0 is the initial wavelength bandwidth of the chirp fiber grating, Δλ 0 is the initial wavelength spacing in the superimposed chirp fiber grating, and t is the superimposed chirp fiber grating. The thickness of the cantilever beam attached, L is the length of the cantilever beam, ρ e represents the photoelastic constant.

상기 수학식 1에서 나타난 바와 같이, 구부림의 정도에 따라 파장 간격이 변함을 알 수 있다. 즉, 구부림이 증가함에 따라 x, y 축상의 성분 좌표가 변하므로 결국 구부림이 증가할수록 파장 간격이 증가함을 알 수 있다. 특히, 첩 광섬유 격자 자체가 넓은 파장 영역을 가지고 있으므로 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터의 파장 영역도 넓으며 다채널 특성을 가지고 있다.As shown in Equation 1, it can be seen that the wavelength interval changes according to the degree of bending. That is, as the bending increases, the component coordinates on the x and y axes change, and thus, the wavelength interval increases as the bending increases. In particular, since the chirp fiber grating itself has a wide wavelength region, the wavelength region of the superimposed chirp fiber grating based multichannel filter is also wide and has multichannel characteristics.

이러한 중첩된(superimposed) 첩 광섬유 격자를 이용하여 좌우 대칭적인 첩 비율 변화를 유도하면 다채널 파장 간격을 증가 또는 감소시킬 수 있는 파장 가변형 다채널 필터를 구현할 수 있다. The superimposed chirp fiber grating can be used to implement a tunable multichannel filter that can increase or decrease the multichannel wavelength spacing by inducing lateral symmetry of the chirp ratio.

도 2는 도 1의 중첩된 첩 광섬유 격자의 중앙을 중심으로 S-자 형태의 구부림을 인가하여 첩 비율을 증가시키는 실험예이다.FIG. 2 is an experimental example of increasing the chirp ratio by applying an S-shaped bend around the center of the superposed chirp optical fiber grating of FIG. 1.

도 2에 나타난 바와 같이, 중첩된(superimposed) 첩 광섬유 격자의 중앙을 중심으로 S-자 형태의 구부림을 인가하면 왼편에는 압축(compression)과 오른편에는 팽창(tension) 변형(strain)이 유도되어 격자 전체적으로 중첩된 첩 광섬유 격자 내부의 첩 비율이 증가하므로 파장 대역폭이 증가하면서 파장간격이 증가한다. As shown in FIG. 2, applying an S-shaped bend around the center of a superimposed chirped optical fiber grating induces compression on the left side and tension strain on the right side, thereby inducing the grating. As the overall rate of chirp inside the overlapped chirp fiber grating increases, the wavelength spacing increases as the wavelength bandwidth increases.

도 3 및 도 4는 도 2의 실험예에 따라 첩 비율 증가에 따른 파장 간격 및 채널 간격의 증가를 나타낸 결과도이다.3 and 4 are result diagrams showing the increase in the wavelength interval and the channel interval according to the increase of the chirp ratio according to the experimental example of FIG.

도 3 및 도 4를 참조하면, D는 구부림을 증가시키기 위한 도 2의 양쪽 블록(moving pivot)의 이동 거리로서 D의 값이 y축 방향으로 0mm, 3mm, 6mm, 9mm로 증가할수록 구부림이 증가되어 파장 대역폭이 증가하면서 파장 간격(Δλ)이 증가함을 알 수 있다. 특히, 좌우 대칭적으로 구부림을 인가하여 첩 비율의 대칭적인 변화를 유도함으로써 공진 파장의 이동은 억제되었음을 알 수 있다. Referring to FIGS. 3 and 4, D is a moving distance of both moving pivots of FIG. 2 to increase bending, and the bending increases as the value of D increases to 0 mm, 3 mm, 6 mm, and 9 mm in the y-axis direction. As the wavelength bandwidth increases, the wavelength interval Δλ increases. In particular, it can be seen that the shift of the resonant wavelength is suppressed by inducing symmetrical change in the chirp ratio by applying the symmetrical bending.

도 5는 도 1의 중첩된 첩 광섬유 격자의 중앙을 중심으로 도 2와 반대방향으로 S-자 형태의 구부림을 인가하여 첩 비율을 감소시키는 실험예이다.FIG. 5 is an experimental example of reducing the chirp ratio by applying an S-shaped bend in a direction opposite to FIG. 2 with respect to the center of the superposed chirp optical fiber grating of FIG. 1.

도 5에 나타난 바와 같이, 중첩된(superimposed) 첩 광섬유 격자의 중앙을 중심으로 왼편에는 팽창(tension)과 오른편에는 압축(compression) 변형(strain)이 유도되어 반대 방향으로 S-자 형태의 구부림을 인가하면 전체적으로 중첩된 첩 광섬유 격자 내부의 첩 비율이 감소하므로 파장 대역폭이 감소하면서 파장 간격이 감소한다. As shown in FIG. 5, an extension strain on the left side and a compression strain on the right side are induced around the center of the superimposed chirped optical fiber grating to form an S-shaped bend in the opposite direction. When applied, the percentage of chirp inside the overlapped chirp optical fiber grating is reduced, thereby reducing the wavelength spacing while reducing the wavelength spacing.

도 6 및 도 7은 도 5의 실험예에 따라 첩 비율 감소에 따른 파장 간격 및 채널 간격의 감소를 나타낸 결과도이다.6 and 7 are result diagrams showing the reduction of the wavelength interval and the channel interval according to the reduction of the chirp ratio according to the experimental example of FIG.

도 6 및 도 7을 참조하면, 도 5와 같이 반대방향으로 구부림이 증가함에 따라 즉, D의 값이 y축방향의 0mm, -5mm, -9mm로 반대로 증가됨에 따라 파장 대역폭이 감소하면서 파장 간격(Δλ)이 감소함을 알 수 있다. 구부림이 대칭적으로 가해지므로 공진 파장의 이동을 억제할 수 있을 뿐만 아니라 입력 편광 상태에도 무관한 기능성 가변 다채널 필터를 구현할 수 있다.Referring to FIGS. 6 and 7, as the bend increases in the opposite direction as shown in FIG. 5, that is, as the value of D increases inversely to 0 mm, -5 mm, and -9 mm in the y-axis direction, the wavelength bandwidth decreases and the wavelength interval is decreased. It can be seen that (Δλ) decreases. The bending is applied symmetrically, which not only suppresses the shift of the resonant wavelength but also enables the implementation of a functional variable multichannel filter independent of the input polarization state.

상술한 도 2 및 도 5에서는 첩 비율의 조절을 구부림에 의하여 조절하였지 만, 이에 한정되지 않으며 당업자의 선택에 의해 온도 조절 또는 스트레인(strain) 등의 방법에 의하여 첩 비율을 조절할 수도 있다.2 and 5 described above, the adjustment of the chirp ratio is controlled by bending, but is not limited thereto. The chirp ratio may be adjusted by a method such as temperature control or strain by a person skilled in the art.

본 발명은 중첩된 첩 광섬유 격자의 첩 비율을 좌우 대칭적으로 변화시킴으로써 채널 간격을 자유롭게 증가 및 감소시킬 수 있다.The present invention can freely increase and decrease the channel spacing by changing the chirp ratio of the superposed chirp fiber grating symmetrically.

또한, 본 발명은 종래의 다채널 필터의 단점인 공진 파장의 변화 및 입력신호의 편광 상태 의존도를 억제할 수 있다.In addition, the present invention can suppress the change in the resonance wavelength and the polarization state dependency of the input signal, which is a disadvantage of the conventional multichannel filter.

따라서, 본 발명은 다채널 스위치 소자, 신호 게이팅 소자, 인터리버(interleaver) 및 다파장 광섬유 레이저 구현에 용이하게 이용될 수 있다.Therefore, the present invention can be easily used for the implementation of a multichannel switch element, a signal gating element, an interleaver, and a multi-wavelength fiber laser.

Claims (8)

제 1 첩 광섬유 격자; 및First chief optical fiber grating; And 상기 제 1 첩 광섬유 격자와 오프셋(offset) 길이만큼 간격을 두고 겹쳐지게 형성되는 제 2 첩 광섬유 격자를 포함하여 다채널 필터를 형성하며,Forming a multi-channel filter including a second chirp optical fiber grating formed to overlap with the first chirp optical fiber grating at an offset length; 다채널 특성을 갖는 샘플링 첩 광섬유 격자의 구조를 포함하는 것을 특징으로 하는 중첩된(superimposed) 첩 광섬유 격자 기반 파장 간격 가변형 다채널 필터.A superimposed chirp optical fiber grating based wavelength spacing variable multichannel filter comprising the structure of a sampling chirp optical fiber grating having multichannel characteristics. 삭제delete 제 1 항에 있어서,The method of claim 1, 상기 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터의 첩 비율은 구부림, 온도 조절 및 스트레인(strain) 중 어느 하나의 방법으로 좌우 대칭되게 조절되는 것을 특징으로 하는 중첩된(superimposed) 첩 광섬유 격자 기반 파장 간격 가변형 다채널 필터.The superimposed chirp fiber optic grating base is characterized in that the chirp ratio of the superimposed chirp fiber grating based multichannel filter is symmetrically adjusted by any one of bending, temperature control, and strain. Wavelength-variable multichannel filter. 삭제delete 제 1 첩 광섬유 격자; 및First chief optical fiber grating; And 상기 제 1 첩 광섬유 격자와 오프셋(offset) 길이만큼 간격을 두고 겹쳐지게 형성되는 제 2 첩 광섬유 격자를 포함하고,A second chirp optical fiber grating formed to overlap with the first chirp optical fiber grating at an offset length; 상기 제 1 첩 광섬유 격자 및 제 2 첩 광섬유 격자는 외팔보에 부착되고, 상기 제 1 첩 광섬유 격자 및 제 2 첩 광섬유 격자의 중앙을 중심으로 S-자 형태의 구부림이 인가된 것을 특징으로 하는 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터.The first and second chirp optical fiber gratings are attached to the cantilever beam, and an S-shaped bend is applied around the center of the first and second chirp optical fiber gratings. (superimposed) Photorealistic grating based multichannel filter. 제 5 항에 있어서,The method of claim 5, 상기 오프셋(offset) 길이 간격이 길면 다채널의 파장 간격이 줄어들고, 상기 오프셋 길이 간격이 짧으면 다채널의 파장 간격이 증가하는 것을 특징으로 하는 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터.The superimposed chirped fiber grating based multichannel filter according to claim 1, wherein the offset length interval is reduced, the wavelength interval of the multichannel is reduced, and when the offset length interval is short, the wavelength interval of the multichannel is increased. 제 6 항에 있어서,The method of claim 6, 상기 중첩된(superimposed) 첩 광섬유 격자 기반 다채널 필터의 첩 비율은 구부림, 온도 조절 및 스트레인(strain) 중 어느 하나의 방법으로 좌우 대칭되게 조절되는 것을 특징으로 하는 중첩된(superimposed) 첩 광섬유 격자 기반 파장 간격 가변형 다채널 필터.The superimposed chirp fiber optic grating base is characterized in that the superposition ratio of the superimposed chirp optical fiber grating based multichannel filter is symmetrically adjusted by any one of bending, temperature control and strain. Wavelength-variable multichannel filter. 삭제delete
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