Optical Characteristics of a Hybrid Fiber Grating Based on a Surface Long-period Grating Incorporating a Fiber Bragg Grating

김현주,전나람,한영근 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.9

A hybrid grating based on a surface long-period grating (SLPG) incorporating a fiber Bragg grating (FBG) is proposed and its optical characteristics are experimentally investigated as external temperature and ambient refractive index are changed. For the fabrication of the hybrid grating, a FBG is firstly fabricated by using a beam scanning technique with a frequency doubled Ar<SUP>+</SUP> laser and then some portion of the cladding region without the FBG is removed by using a side polishing technique. The SLPG is formed on the flat surface of the side-polished fiber (D-shaped fiber) by using a standard contact lithography technique. The transmission spectrum of the hybrid grating is superimposed on those for the SLPG and the FBG. The variation of external refractive index and temperature can modify the transmission characteristics of the proposed hybrid grating. The ambient index sensitivity of the resonant peak induced by the SLPG was measured to be 880.7 nm/RIU while the resonant peak generated by the FBG was kept constant as the ambient index changed in an index range from 1.30 to 1.45. The temperature sensitivities of two resonant peaks for the SLPG and the FBG were measured to be -0.52 nm/°C and 0.01 nm/°C, respectively. Accordingly, we expect that it is possible to discriminate two concurrent sensitivities, such as external refractive index and temperature sensitivities by using the hybrid fiber grating.

Femtosecond-laser-assisted Fabrication of Double-layer Diffraction Gratings inside Fused Silica Glass

최훈국,손익부,노영철,이용택,김진태,Shamim Ahsan 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.1

We have fabricated double-layer diffraction gratings with a zigzag shape inside fused silica glass byusing a femtosecond laser, the intention of which is to overcome the hindrance of shortening grating’speriod. Our primary focus is to utilize double-layer gratings to achieve a diffraction pattern similarto that from a single-layer diffraction grating with the same period as the double-layer grating. Wefabricated two kinds of double-layer gratings, where the grating’s period was either 6 μm or 2 μmfor both layers. The first set of diffraction gratings was printed 70 μm inside the glass substrates. This layer was followed by the second layer grating engraved just below the first layer grating (Theshifted grating’s position was shifted to the right by 3 μm for the 6-μm-period grating and by 1 μmfor the 2-μm-period grating). By varying the layer gap, we have found the optimal position (layergap: 500 nm) to achieve a diffraction pattern similar to that of a single-layer diffraction gratingwith half the grating’s period of the double-layer gratings.

금속 그레이팅의 높이변화에 따른 최적치수 설계 및 안정성 해석

손인수 한국산업융합학회 2022 한국산업융합학회 논문집 Vol.25 No.3

In this study, in order to develop an non-slip metal grating, the stability of the grating according to the span of the grating and the gap and height of the bearing bar was evaluated. The optimal shape design of the grating was performed using the results of determining the stability of the grating. The purpose of this study is to determine the stability according to the spacing and height of the bearing bar by applying the design pressure at the design stage to develop the anti-skid grating, and to design the optimal shape for cost reduction. In the optimal design, the target variable was set as the mass, and the optimal design of the grating was performed based on about 20%. Regardless of the height of the bearing bar of the grating, the stress and deformation of the span and the grating showed a proportional tendency to each other, and it was found that the stress decreased as the height of the bearing bar increased. Based on the structural analysis results, an optimal design was performed using mass as the objective variable, and the existing 2mm thickness was changed to 1.6mm, reducing the mass by about 19%. The stress increased by about 4.4% compared to the maximum stress of the existing grating, but the minimum safety factor was 3.1, indicating that the optimally designed grating was stable.

고리형 위상 격자의 공간 주파수 필터 효과

김인길,고춘수,임성우,오용호,이재철 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.9

We studied the characteristics of annular phase gratings as spatial frequency filters. We first calculated the Fraunhofer diffraction patterns of annular gratings and then got the modulation transfer function (MTF) from the zeroth order Hankel transform of the intensity distribution function. Binaryphase annular grating shows higher diffraction efficiency than binary phase rectangular grating. But the MTF decreases linearly in the low-frequency region as that of rectangular grating does. The diffraction pattern of 4-phase annular grating is similar to that of 2-phase grating and hence MTFs of the two are much alike. For 8-phase annular grating, the 7th order diffracted beam is the lowest one next to the first. Consequently, the diffraction efficiency is very high and the MTF graph is curved upward. The diffracted beams except the first order are negligible and hence the MTF characteristics are more improved in the case of 16-phase grating. But the degree of improvement becomes lowered c(Impaled with 8-phase grating. We made a 16-phase annular grating and measured its MTF. The experimental result agrees well with the calculated one.

기계적으로 유도되는 장주기 광섬유 격자 배열 소자 및 센서 응용

이남권,송재원,박재희,Lee, Nam-Kwon,Song, Jae-Won,Park, Jea-Hee 한국광학회 2007 한국광학회지 Vol.18 No.2

기계적으로 유도되는 장주기 광섬유 격자 배열 소자를 제작하고 격자 배열소자의 광 투과 특성을 측정하였다. 격자 배열 소자는 표면에 $690{\mu}m$부터 $780{\mu}m$ 주기까지 $10{\mu}m$씩 주기가 증가되는 격자들이 만들어져 있는 45 cm 길이의 금속 막대와 고무덮개로 구성되어 있다. 외부 압력이 격자 배열 소자에 인가되면 압력이 인가된 지점에만 장주기 광섬유 격자가 형성되고 장주기 광섬유 격자의 공진 파장은 인가된 지점에 의존한다. 그리고 제작된 장주기 광섬유 격자 배열 소자의 특성측정 결과가 다양한 투과 특성을 갖는 광섬유 대역 제거 필터, 혹은 압력센서로 사용 가능함을 보여주고 있다. A mechanically induced long-period fiber grating array was fabricated and its transmission characteristics were measured. The grating away consisted of a rubber cover and a 45 cm metal bar with 10 grating groups. Each grating group was composed of 60 gratings. The period of the grating of the grating groups was increased by $10{\mu}m$ increments from $690{\mu}m$ to $780{\mu}m$. The long period fiber grating was induced when the pressure was applied on the long period grating array and the resonant wavelength depended on the position of applied pressure. The experimental results shows that this long period fiber grating away can be used as a various band rejection filter or a fiber optic sensor.

Non-resonant 3D Elliptical Vibration Cutting Induced Submicron Grating Coloring

Jianzhong Chen,Mingming Lu,Jieqiong Lin,Jiakang Zhou,Xifeng Fu,Xiaoqin Zhou 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.4

Surface Submicron grating manufacturing has broad application prospects, which has also been the subject of intensive research and development by scholars with many eff orts. In this paper, a grating coloring manufacturing method is proposed based on three-dimensional elliptical vibration cutting and non-resonant piezoelectric actuator. Based on the mechanism of elliptical motion, an effective cutting depth model was established. Nonlinear interaction of machining parameters (overlap rate, nominal cutting speed, vibration frequency) on the geometry of the grating were analyzed and controllable modulation model of grating geometry was established. The geometrical dimensions of the grating were predicted and grooved experiments were performed on brass and aluminum surfaces. A set of angle-adjustable detection device was designed independently to check the diffraction quality of the grating. The quantitative experimental results show that grating distances of copper and aluminum rods are 752 nm and 684 nm, respectively. The average width of the aluminum rod overall grating is 764 nm, the accuracy error is 9.25%. In addition, aluminum rod gratings can diffractred light at non-specific angles, which is more effective at viewing angle of 70°. The experimental results are in agreement with the theory which have positive significance for expanding the functional surface.

광변조기의 양방향 변조를 이용한 chirped fiber grating의 시간지연 측정법

전금수,이용구,반재경,허현,Jeon, Geum-Soo,Lee, Yong-Gu,Ban, Jae-Kyung,Heo, Hyun 한국광학회 2002 한국광학회지 Vol.13 No.6

본 논문에서는 Mach-Zehnder변조기 양방향 변조를 이용하여 chirped fiber grating의 시간지연을 측정할 수 있는 간단한 시스템을 제안하였다. 시간차를 두고 양방향 변조된 광신호는 RF영역에서 주기적인 간섭무늬를 만들게 된다. 이러한 광파장에 따라 변하는 간섭무늬의 주기를 측정하여 chirped fiber grating의 시간지연을 측정할 수 있다 5cm의 chirp과3.16nm의 대역폭을 갖는 chi ed fiber grating의 시간지연을 측정하였으며 측정된 시간지연의 평균 기울기는 183ps/nm이고 고1.7%보다 작은 오차 범위에서 측정되었다. A simple method for a time delay measurement of a chirped fiber grating by using bidirectional modulation of a Mach-Zehnder modulator has been proposed. The bidirectionally modulated light with time difference makes an interference fringe in the RF domain. The time delay of a chirped fiber grating can be obtained by measuring the period of the RF interference fringe for different wavelengths. We have measured the time delay of a chirped fiber grating with a chirped length of 5 cm and a bandwidth of 3.16 nm. The average slope of the time delay has been measured to be 183 ps/nm and its uncertainty has been less than $\pm$1.7%.

2-Dimensional Holographic Grating Formation in Chalcogenide Thin Films

Jung-Tae Lee,정홍배,Choel-Ho Yeo 한국전기전자재료학회 2004 Transactions on Electrical and Electronic Material Vol.5 No.1

Amorphous chalcogenide thin films, especially a-(Se, S) based films, exhibit a number of photo-induced phenomena. In this study, we make the As40Ge10Se15S35/Ag thin film and then we measure the holographic diffraction efficiency according to thickness of Ag. And we form the two-dimensional holographic grating. At first, we formed one-dimensional grating and then we form two-dimensional grating by rotate the sample. We found out the most suitable thickness of Ag and in case of As40Ge10Se15S35/Ag(600Å), the diffraction efficiency was more higher than other samples. The holographic grating was formed by He-Ne laser(λ=632.8nm). The intensity of incident beam was 2.5mW and incident angle was 20°. We confirm the two-dimensional holographic grating by the pattern of diffracted beam and AFM(Atomic Force Microscope) image. We perform the etching process using by 0.26N NaOH in order to confirm clearly two-dimensional grating.

미끄럼 방지용 금속 그레이팅의 구조적 안정성 평가

손인수 ( In-soo Son ) 한국산업융합학회 2021 한국산업융합학회 논문집 Vol.24 No.4

In this study, In order to prevent the safety accidents caused by the sliding, to develop the non-slip grating, the stability judgment based on the span length of the grating and the gap of the bearing bar is performed. The structural analysis of Grating was carried out in accordance with the provisions set out in Grating’s load-bearing test conditions. As the span length increases, the deflection increases and the stress and span length tend to be proportional to each other. It was shown that the larger the span, the linear increase in stress and exponential increase in deformation of grating. The maximum stress of grating was approximately 58.2 MPa, indicating a very stable safety rate of about 4.3 compared to the yield strength of the grating material. Based on these results, it will be able to be utilized as the basic data for determining the optimal dimensions of non-slip grading by performing optimal designs in the future.

2-Dimensional Holographic Grating Formation in Chalcogenide Thin Films

Lee, Jung-Tae,Yeo, Choel-Ho,Chung, Hong-Bay The Korean Institute of Electrical and Electronic 2004 Transactions on Electrical and Electronic Material Vol.5 No.1

Amorphous chalcogenide thin films, especially a-(Se, S) based films, exhibit a number of photo-induced phenomena. In this study, we make the As$\_$40/Ge$\_$10/Se$\_$15/S$\_$35//Ag thin film and then we measure the holographic diffraction efficiency according to thickness of Ag. And we form the two-dimensional holographic grating. At first, we formed one-dimensional grating and then we form two-dimensional grating by rotate the sample. We found out the most suitable thickness of Ag and in case of As$\_$40/Ge$\_$10/Se$\_$15/S$\_$35//Ag(600${\AA}$), the diffraction efficiency was more higher than other samples. The holographic grating was formed by He-Ne laser(λ=632.8nm). The intensity of incident beam was 2.5mW and incident angle was 20$^{\circ}$. We confirm. the two-dimensional holographic grating by the pattern of diffracted beam and AFM(Atomic Force Microscope) image. We perform the etching process using by 0.26N NaOH in order to confirm clearly two-dimensional grating.