Pub Date : 2016-12-25DOI: 10.3807/KJOP.2016.27.6.212
Bup-Joong Kim, J. Ryoo, Kyoungrok Cho
In connection-oriented data-transport services, data loss can occur when the service experiences a problem on its end-to-end path. To promptly resolve this problem, the data-switching systems providing the service should quickly modify their internal configurations distributed among different places in each system. This is performed through a sequence of problem (event) recognition, sharing, and handling procedures among multiple control processors in the system. This paper proposes a method for event sharing and messaging between control processors, to improve the time determinacy of event processing. This method simplifies runtime event sharing and minimizes the time variability caused by the event data, resulting in a decrease in the latency time in processing global events. The proposed method lessens the latency time of global event processing by about 40%, compared to general methods, for 738 internal path changes.
{"title":"Time-Deterministic Event Processing in Terabit Optical-Circuit-Packet Converged Switching Systems","authors":"Bup-Joong Kim, J. Ryoo, Kyoungrok Cho","doi":"10.3807/KJOP.2016.27.6.212","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.6.212","url":null,"abstract":"In connection-oriented data-transport services, data loss can occur when the service experiences a problem on its end-to-end path. To promptly resolve this problem, the data-switching systems providing the service should quickly modify their internal configurations distributed among different places in each system. This is performed through a sequence of problem (event) recognition, sharing, and handling procedures among multiple control processors in the system. This paper proposes a method for event sharing and messaging between control processors, to improve the time determinacy of event processing. This method simplifies runtime event sharing and minimizes the time variability caused by the event data, resulting in a decrease in the latency time in processing global events. The proposed method lessens the latency time of global event processing by about 40%, compared to general methods, for 738 internal path changes.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"212-217"},"PeriodicalIF":0.1,"publicationDate":"2016-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-12-25DOI: 10.3807/KJOP.2016.27.6.218
Byeong-Gwan Ji, Seung-Gol Lee, Se-Guen Park, O. Beom-hoan
레이저 다이오드 TO 패키지 내부의 주요 부분과 히트싱크 구조의 열전달 특성을 전산모사를 통해 분석하고, 개선구조의 효율적 적용방안을 제안하였다. 열 병목 현상을 개선하기 위해, 레이저 다이오드 상부에 열 우회를 도모할 수 있는 방열구조물을 설치하는 것을 제안하였고, 열저항 단순모델 기대치와 비교하여 그 우회...
{"title":"Thermal Characteristics of a Heat Sink with Bypass Structure for GaN-based Laser Diode","authors":"Byeong-Gwan Ji, Seung-Gol Lee, Se-Guen Park, O. Beom-hoan","doi":"10.3807/KJOP.2016.27.6.218","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.6.218","url":null,"abstract":"레이저 다이오드 TO 패키지 내부의 주요 부분과 히트싱크 구조의 열전달 특성을 전산모사를 통해 분석하고, 개선구조의 효율적 적용방안을 제안하였다. 열 병목 현상을 개선하기 위해, 레이저 다이오드 상부에 열 우회를 도모할 수 있는 방열구조물을 설치하는 것을 제안하였고, 열저항 단순모델 기대치와 비교하여 그 우회...","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"218-222"},"PeriodicalIF":0.1,"publicationDate":"2016-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-12-25DOI: 10.3807/KJOP.2016.27.6.223
S. Y. Kim
The birefringence of distributed, uniaxially anisotropic molecules like liquid crystals is calculated as the degree of ordering is varied. The relation between the normalized birefringence and the orientational order parameter is investigated. The distribution function, which enables one to monitor the degree of ordering of liquid crystals including randomly distributed ones, is introduced. Using this distribution function, a series of distributed liquid crystals with order parameters ranging from 0 to 1 are generated, and and of the correspondingly distributed liquid crystals are calculated. Based on the calculated data, it is revealed that and satisfy the quasi-linear relation of , where can be approximated as . The anisotropy of molecular polarizability is also calculated, using the birefringence, and separately following Vuks’ method and Neugebauer’s method, and it is shown that the relations between and the molecular-polarizability anisotropy are also quasi-linear.
{"title":"The Explicitly Quasi-linear Relation Between the Order Parameter and Normalized Birefringence of Aligned Uniaxially Anisotropic Molecules Determined Using a Numerical Method","authors":"S. Y. Kim","doi":"10.3807/KJOP.2016.27.6.223","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.6.223","url":null,"abstract":"The birefringence of distributed, uniaxially anisotropic molecules like liquid crystals is calculated as the degree of ordering is varied. The relation between the normalized birefringence and the orientational order parameter is investigated. The distribution function, which enables one to monitor the degree of ordering of liquid crystals including randomly distributed ones, is introduced. Using this distribution function, a series of distributed liquid crystals with order parameters ranging from 0 to 1 are generated, and and of the correspondingly distributed liquid crystals are calculated. Based on the calculated data, it is revealed that and satisfy the quasi-linear relation of , where can be approximated as . The anisotropy of molecular polarizability is also calculated, using the birefringence, and separately following Vuks’ method and Neugebauer’s method, and it is shown that the relations between and the molecular-polarizability anisotropy are also quasi-linear.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"223-228"},"PeriodicalIF":0.1,"publicationDate":"2016-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-12-25DOI: 10.3807/KJOP.2016.27.6.229
SaeJune Park, Ahn, Yeonghwan
Metamaterials operating in the terahertz frequency range show promising potential for use in highly sensitive microbial sensors that are capable of effectively detecting microorganisms in the ambient environment. We were able to detect extremely small numbers of microorganisms by measuring the differential transmission spectra (DTS) of the metamaterial resonances. This was possible because their sizes are on the same scale as the microgaps of the terahertz metamaterials. DTS depend critically on the number of microorganisms placed in the gap area, and their dielectric constant. In addition, these metamaterial microbial sensors are reusable, because the microorganisms can be completely removed by fungicide solution. Finite-difference time-domain simulations successfully reproduce our experimental data.
{"title":"Differential Transmission Spectra of Terahertz Metamaterial Resonances for Sensing Microorganisms","authors":"SaeJune Park, Ahn, Yeonghwan","doi":"10.3807/KJOP.2016.27.6.229","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.6.229","url":null,"abstract":"Metamaterials operating in the terahertz frequency range show promising potential for use in highly sensitive microbial sensors that are capable of effectively detecting microorganisms in the ambient environment. We were able to detect extremely small numbers of microorganisms by measuring the differential transmission spectra (DTS) of the metamaterial resonances. This was possible because their sizes are on the same scale as the microgaps of the terahertz metamaterials. DTS depend critically on the number of microorganisms placed in the gap area, and their dielectric constant. In addition, these metamaterial microbial sensors are reusable, because the microorganisms can be completely removed by fungicide solution. Finite-difference time-domain simulations successfully reproduce our experimental data.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"229-232"},"PeriodicalIF":0.1,"publicationDate":"2016-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-12-25DOI: 10.3807/KJOP.2016.27.6.203
J. Youn, K. Im
We have studied the hybrid method for reconstructing apodized chirped fiber Bragg gratings, using both an analytic estimation of grating parameters and an optimization algorithm. The Hilbert transform of the reflection spectrum was utilized to estimate grating parameters, and then the layer-peeling algorithm was used to obtain refined parameter values by the differential-evolution optimization process. Calculations for a fiber Bragg grating with wavelength chirp rate 2 nm/cm were obtained with an accuracy of 6 × 10 -5 nm/cm for the chirp rate and 3 × 10 -9 for the index modulation, with much improved calculation speed and high reliability.
{"title":"Hybrid Optimization Method for the Reconstruction of Apodized Chirped Fiber Bragg Gratings","authors":"J. Youn, K. Im","doi":"10.3807/KJOP.2016.27.6.203","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.6.203","url":null,"abstract":"We have studied the hybrid method for reconstructing apodized chirped fiber Bragg gratings, using both an analytic estimation of grating parameters and an optimization algorithm. The Hilbert transform of the reflection spectrum was utilized to estimate grating parameters, and then the layer-peeling algorithm was used to obtain refined parameter values by the differential-evolution optimization process. Calculations for a fiber Bragg grating with wavelength chirp rate 2 nm/cm were obtained with an accuracy of 6 × 10 -5 nm/cm for the chirp rate and 3 × 10 -9 for the index modulation, with much improved calculation speed and high reliability.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"203-211"},"PeriodicalIF":0.1,"publicationDate":"2016-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-10-25DOI: 10.3807/KJOP.2016.27.5.181
Jin-Woong Lee, Jung Woo Lee, Younghoon Kim, K. Hyun
We report on the parameter-dependent optical characteristics of the unidirectional single-mode lasing square ring cavities. Using the taper-step section in the square cavities, the resonant direction can be selected and we characterize the optical losses by changing the taper lengths. Various kinds of square ring cavities are fabricated, based on InGaAsP/InGaAs multiple quantum well semiconductor materials. From the experimental results we obtain the optimized taper length for a given device structure, while maintaining unidirectional single-mode lasing.
{"title":"Optical Characteristics of Unidirectional Single-mode Lasing Square Ring Cavities","authors":"Jin-Woong Lee, Jung Woo Lee, Younghoon Kim, K. Hyun","doi":"10.3807/KJOP.2016.27.5.181","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.5.181","url":null,"abstract":"We report on the parameter-dependent optical characteristics of the unidirectional single-mode lasing square ring cavities. Using the taper-step section in the square cavities, the resonant direction can be selected and we characterize the optical losses by changing the taper lengths. Various kinds of square ring cavities are fabricated, based on InGaAsP/InGaAs multiple quantum well semiconductor materials. From the experimental results we obtain the optimized taper length for a given device structure, while maintaining unidirectional single-mode lasing.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"181-187"},"PeriodicalIF":0.1,"publicationDate":"2016-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-10-25DOI: 10.3807/KJOP.2016.27.5.174
Kyoung-Soo Kim, H. Moon, Youngchul Chung
A tunable optical delay line is designed, fabricated, and characterized. The tunable delay line consists of four polymer-ring add/drop filters with delay waveguides between adjacent ones. The polymer waveguide is a buried structure, designed to be square with core width and height of 1.8 μm. The refractive indices of the core and cladding polymer are 1.48 and 1.37 respectively. The large index difference and small cross section of the waveguide enable us to realize a compact device using a small radius of curvature. Four pairs of electrodes are evaporated above the add/drop filters to provide heating currents for thermal tuning. In measurements we can identify variable time delays of 110, 225, and 330 ps in proportion to the number of delay lines.
{"title":"Tunable Optical Delay Line Based on Polymer Single-Ring Add/Drop Filters and Delay Waveguides","authors":"Kyoung-Soo Kim, H. Moon, Youngchul Chung","doi":"10.3807/KJOP.2016.27.5.174","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.5.174","url":null,"abstract":"A tunable optical delay line is designed, fabricated, and characterized. The tunable delay line consists of four polymer-ring add/drop filters with delay waveguides between adjacent ones. The polymer waveguide is a buried structure, designed to be square with core width and height of 1.8 μm. The refractive indices of the core and cladding polymer are 1.48 and 1.37 respectively. The large index difference and small cross section of the waveguide enable us to realize a compact device using a small radius of curvature. Four pairs of electrodes are evaporated above the add/drop filters to provide heating currents for thermal tuning. In measurements we can identify variable time delays of 110, 225, and 330 ps in proportion to the number of delay lines.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"174-180"},"PeriodicalIF":0.1,"publicationDate":"2016-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-10-25DOI: 10.3807/KJOP.2016.27.5.165
Sang-Hu Heo, Chung-Ghiu Lee
{"title":"Three-dimensional Geometrical Scanning System Using Two Line Lasers","authors":"Sang-Hu Heo, Chung-Ghiu Lee","doi":"10.3807/KJOP.2016.27.5.165","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.5.165","url":null,"abstract":"","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"165-173"},"PeriodicalIF":0.1,"publicationDate":"2016-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-08-25DOI: 10.3807/KJOP.2016.27.4.133
Gunzung Kim, Yongwan Park
본 논문에서는 DS-OCDMA(direct sequence optical code division multiple access)와 스캐닝 방식의 MEMS (microelectromechanical system) 거울을 이용하여 픽셀별로 스캐닝하는 라이다 시스템(light detection and ranging, LIDAR)의 설계와 시뮬레이션 결과를 기술한다. 제안하는 라이다는 $848{times}480$ 해상도의 ...
本文由DS-OCDMA(direct sequence optical code division multiple access)和扫描系统microelectromechanical system (microelectromechanical system)利用镜子对像素进行扫描的照明系统(light detection and ranging)。(LIDAR)的设计和模拟结果。提议的莱达$848{times}480分辨率…
{"title":"Long Distance and High Resolution Three-Dimensional Scanning LIDAR with Coded Laser Pulse Waves","authors":"Gunzung Kim, Yongwan Park","doi":"10.3807/KJOP.2016.27.4.133","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.4.133","url":null,"abstract":"본 논문에서는 DS-OCDMA(direct sequence optical code division multiple access)와 스캐닝 방식의 MEMS (microelectromechanical system) 거울을 이용하여 픽셀별로 스캐닝하는 라이다 시스템(light detection and ranging, LIDAR)의 설계와 시뮬레이션 결과를 기술한다. 제안하는 라이다는 $848{times}480$ 해상도의 ...","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"133-142"},"PeriodicalIF":0.1,"publicationDate":"2016-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-08-25DOI: 10.3807/KJOP.2016.27.4.143
H. Cho, Jun-Yeon Won, Young-Gyu Jeong, B. Woo, Junho Yoon, C. Hwangbo
The thickness of each layer in a multilayered system is determined by a Fourier-transform method using spectroscopic reflectance measurements. To verify this method, we first generate theoretical reflectance spectra for three layers, and these are fast-Fourier-transformed using our own Matlab program. Each peak of the Fourier-transformed delta function denotes the optical thickness of each layer, and these are transformed to physical thicknesses. The relative thickness error of the theoretical model is less than 1.0% while a layer’s optical thickness is greater than 730 nm. A PI-(thin SiO 2 )-PImultilayeredstructure produced by the bar-coating method was analyzed, and the thickness errors compared to SEM measurements. Even though this Fourier-transform method requires knowing the film order and the refractive index of each layer prior to analysis, it is a fast and nondestructive method for the analysis of multilayered structures.
{"title":"Determining the Thickness of a Trilayer Thin-Film Structure by Fourier-Transform Analysis","authors":"H. Cho, Jun-Yeon Won, Young-Gyu Jeong, B. Woo, Junho Yoon, C. Hwangbo","doi":"10.3807/KJOP.2016.27.4.143","DOIUrl":"https://doi.org/10.3807/KJOP.2016.27.4.143","url":null,"abstract":"The thickness of each layer in a multilayered system is determined by a Fourier-transform method using spectroscopic reflectance measurements. To verify this method, we first generate theoretical reflectance spectra for three layers, and these are fast-Fourier-transformed using our own Matlab program. Each peak of the Fourier-transformed delta function denotes the optical thickness of each layer, and these are transformed to physical thicknesses. The relative thickness error of the theoretical model is less than 1.0% while a layer’s optical thickness is greater than 730 nm. A PI-(thin SiO 2 )-PImultilayeredstructure produced by the bar-coating method was analyzed, and the thickness errors compared to SEM measurements. Even though this Fourier-transform method requires knowing the film order and the refractive index of each layer prior to analysis, it is a fast and nondestructive method for the analysis of multilayered structures.","PeriodicalId":42467,"journal":{"name":"Korean Journal of Optics and Photonics","volume":"27 1","pages":"143-150"},"PeriodicalIF":0.1,"publicationDate":"2016-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70159523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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