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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Optical Society of Korea
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Journal DOI :
Optical Society of Korea
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Volume & Issues
Volume 19, Issue 6 - Dec 2015
Volume 19, Issue 5 - Oct 2015
Volume 19, Issue 4 - Aug 2015
Volume 19, Issue 3 - Jun 2015
Volume 19, Issue 2 - Apr 2015
Volume 19, Issue 1 - Feb 2015
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Laser Assisted Fabrication of Micro-lensed Single-mode Optical Fiber
Choi, Hun-Kook ; Yoo, Dongyoon ; Sohn, Ik-Bu ; Noh, Young-Chul ; Sung, Jae-Hee ; Lee, Seong-Ku ; Jeong, Tae-Moon ; Ahsan, Md. Shamim ; Kim, Jin-Tae ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 327~333
DOI : 10.3807/JOSK.2015.19.4.327
This paper reports the fabrication of various micro-lensed single-mode optical fibers through the use of an enhanced peak power
laser beam. The end faces of the optical fibers are exposed to the
laser beam to form convex, concave, and conical shape optical fiber tips. Peak power of the
laser beam was varied from 0.8 W to 1.5 W depending on the shape of the optical fiber tip. We also discover the dependence of the angle of the optical fiber tip on the rotation angle and the number of
laser irradiations. The angle shows an increasing trend with both these parameters. We achieve a wide range of lenticular fibers with end face angle varying from
. Furthermore, we investigate the emission pattern of light from the developed micro-lensed fibers. The proposed
laser based optical fiber reshaping technique shows great consistency, and thus is suitable for commercial applications.
Terabit-Per-Second Optical Super-Channel Receiver Models for Partial Demultiplexing of an OFDM Spectrum
Reza, Ahmed Galib ; Rhee, June-Koo Kevin ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 334~339
DOI : 10.3807/JOSK.2015.19.4.334
Terabit-per-second (Tb/s) transmission capacity for the next generation of long-haul communication networks can be achieved using multicarrier optical super-channel technology. In an elastic orthogonal frequency division multiplexing (OFDM) super-channel transmission system, demultiplexing a portion of an entire spectrum in the form of a subband with minimum power is critically required. A major obstacle to achieving this goal is the analog-to-digital converter (ADC), which is power-hungry and extremely expensive. Without a proper ADC that can work with low power, it is unrealistic to design a 100G coherent receiver suitable for a commercially deployable optical network. Discrete Fourier transform (DFT) is often seen as a primary technique for understanding partial demultiplexing, which can be attained either optically or electronically. If fairly comparable performance can be achieved with an all-optical DFT circuit, then a solution independent of data rate and modulation format can be obtained. In this paper, we investigate two distinct OFDM super-channel receiver models, based on electronic and all-optical DFT-technologies, for partial carrier demultiplexing in a multi-Tb/s transmission system. The performance comparison of the receivers is discussed in terms of bit-error-rate (BER) performance.
Application-Centric, Energy-Efficient Network Architecture ACTION, Based on Virtual Optical Slice Core and Deterministic Optical Access Network
Ashizawa, Kunitaka ; Okamoto, Satoru ; Yamanaka, Naoaki ; Oki, Eiji ; Fumagalli, Andrea ; Veeraraghavan, Malathi ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 340~345
DOI : 10.3807/JOSK.2015.19.4.340
The Internet traffic is forecasted to grow at a compound annual rate of 21 % from 2013 to 2018, according to surveys carried out by Cisco . Network resources are significantly over-provisioned in today's networks, and it is quite common to see link utilization in the 30-40% range . Additionally, the multi-media services have widely divergent bandwidth and Quality of Experience (QoE) requirements. Unfortunately, the huge transmission capacity will increase the power consumption of network equipment . Applications Coordinated with Transport, Internet Protocol and Optical Networks (ACTION)  has been proposed to realize a multi-QoE, application-centric, and highly energy-efficient network that leverages flexible elastic optical network technologies [5-7]. This paper provides key network technologies for realizing the ACTION, which are a virtual optical slice core network and a Time Division Multiplexing (TDM)-based deterministic active optical access network.
Measurement of Effective Refractive Index of Nematic Liquid Crystal in Fabry-Perot Etalon
Ko, Myeong Ock ; Kim, Sung-Jo ; Kim, Jong-Hyun ; Lee, Bong Wan ; Jeon, Min Yong ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 346~350
DOI : 10.3807/JOSK.2015.19.4.346
We report a measurement of the effective refractive index of a nematic liquid crystal (NLC) inside a Fabry-Perot (FP) etalon according to the applied electric fields. The effective refractive index of the NLC depends on the intensity of the applied electric field. A wavelength-swept laser with a polygon-scanner-based wavelength filter is used as a wide-band optical source to measure the effective refractive index of the NLC. The bandwidth of the optical source is greater than 90 nm around 1300 nm. The fabricated NLC FP etalon consists of glass substrates, gold layers as the electrodes with highly reflective surfaces, polyimide layers as the planar alignment layers, and an LC layer. Furthermore, we measured the Freedericksz transition voltages for three types of NLC FP etalons having thicknesses of
. The Freedericksz transition voltages in the three cases are nearly equal. The measured effective refractive indices in the three cases decreased from 1.67 to 1.51 as the applied electric field intensity was increased. Beyond the threshold electric field, the effective refractive indices quickly decreased and eventually saturated at a value of 1.51 for all cases.
Efficient Cross-Room Switch Mechanism for Indoor Room-Division-Multiplexing Based Visible Light Communication Network
Huang, Zhitong ; Xiong, Jieqing ; Li, Jianfeng ; Ji, Yuefeng ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 351~356
DOI : 10.3807/JOSK.2015.19.4.351
Visible light communication (VLC) is considered to be an attractive scheme to realize the broadband wireless communication for an indoor environment. We present a room division multiplexing (RDM) mechanism for an indoor multi-room VLC network, which utilizes the spatial position of the LED lamp in different rooms as a novel dimension of network resource for multiplexing, and thus the network capacity is increased. In such a network, the service interruption caused by user cross-room movement is an important problem, and we propose a double-area-positioning based cross-room switch solution. An experimental platform demonstrates the RDM-deployed VLC network, and validates the performance of the presented switch mechanism.
Improvement of a Pound-Drever-Hall Technique to Measure Precisely the Free Spectral Range of a Fabry-Perot Etalon
Seo, Dong-Sun ; Park, Chongdae ; Leaird, Daniel E. ; Weiner, Andrew M. ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 357~362
DOI : 10.3807/JOSK.2015.19.4.357
We examine the principle of a modified Pound-Drever-Hall (PDH) technique to measure the free spectral range of a Fabry-Perot etalon (FPE). The FPE's periodic transmission of phase-modulated light allows us to adopt a sampling theorem to develop a new relationship for the PDH error signal. This leads us to find the key parameters governing the measurement accuracy: the phase modulation index
and the FPE finesse. Without any additional complexity for background noise reduction, we achieve a measurement accuracy of 0.5 ppm. The improvement is mainly attributed to the wide-band phase modulation approaching
, and partly to the use of both reflected and transmitted light from the FPE and good FPE finesse.
The Waveform Model of Laser Altimeter System with Flattened Gaussian Laser
Ma, Yue ; Wang, Mingwei ; Yang, Fanlin ; Li, Song ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 363~370
DOI : 10.3807/JOSK.2015.19.4.363
The current waveform model of a laser altimeter is based on a Gaussian laser beam of fundamental mode, while the flattened Gaussian beam has many advantages such as nearly constant energy distribution on the center of the cross-section. Following the theory of the flattened Gaussian beam and the waveform theory of the laser altimeter, some of the primary parameters of the received waveform were derived, and a laser altimetry waveform simulator and waveform processing software were programmed and improved under the circumstance of a flattened Gaussian beam. The result showed that the bias between theoretical and simulated waveforms was less than 3% for every order mode, the waveform width and range error would increase as target slope or order number rose. Under higher order mode, the shapes of the received waveforms were no longer Gaussian, and could be fitted more precisely as a generalized Gaussian function with power bigger than 2. The flattened beam got much better performance for a multi-surface target, especially when the small surface is far from the center of the laser footprint. This article provides the waveform theoretical basis for the use of a flattened Gaussian beam in a laser altimeter.
Equivalent Optical Bandwidth of Reflective Electro-Absorption Modulator Based Optical Source with a Broadband Seed Light for a 2.5 Gb/s and Beyond Signal Transmission
Kim, Chul Han ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 371~375
DOI : 10.3807/JOSK.2015.19.4.371
The impact of equivalent optical bandwidth on the performance of a system using a reflective electroabsorption modulator (R-EAM) based optical source has been experimentally evaluated with signals operating at 2.5 Gb/s and beyond. The equivalent optical bandwidth of our source with a broadband seed light was simply adjusted by using a bandwidth tunable optical filter. From the measurements, we have estimated the required equivalent optical bandwidth of our source for an error-free transmission (@ bit-error-rate of
) and a forward error correction (FEC) threshold of
Transmission Characteristics of Long-Period Fiber Gratings Using Periodically Corroded Single-Mode Fibers
Lee, Jonghwan ; Bang, Ngac An ; Han, Young-Geun ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 376~381
DOI : 10.3807/JOSK.2015.19.4.376
Transmission characteristics of long-period fiber gratings (LPFGs) fabricated by periodically etching a conventional single-mode fiber (SMF) are investigated. After coating the SMF with photoresist, the cladding of the SMF is symmetrically and periodically removed by using a wet etching technique resulting in the formation of the LPFG. Tensile strain reinforces the coupling strength between the core and the cladding mode based on the photoelastic effect. The extinction ratio of the SMF-based LPFG at a wavelength of 1550.8 nm is measured to be -15.1 dB when the applied strain is
. The ascent of ambient index shifts the resonant wavelength to shorter wavelength because of the increase of the effective refractive index of the cladding mode. The extinction ratio is diminished by increase in the ambient index because of the induction of the optical attenuation of the cladding mode. The transmission characteristics of the proposed LPFG with variations in torsion are also measured. The photoelastic effect based on torsion changes the extinction ratio and the resonant wavelength of the proposed SMF-based LPFG. The polarization-dependent loss of the LPFG is also increased by torsion because of the torsion-induced birefringence. The polarization-dependent loss of the LPFG at torsion of 8.5 rad/m is measured to be 3.9 dB.
Motility Contrast Imaging for Drug Screening Applications
Jeong, Kwan ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 382~389
DOI : 10.3807/JOSK.2015.19.4.382
Motility contrast imaging is a coherence-domain imaging technique that uses cellular motility as a fully endogenous imaging contrast agent. Motility is measured inside tissue using a digital holographic coherence gate that extracts dynamic speckle from fixed depths. The dynamic speckle arises from the normal organelle motion inside cells, and from the movement of the cellular membranes driven by the cytoskeleton. It measures cellular activity and the effects of temperature and osmolarity. Motion is sensitive to cytoskeletal drugs, such as the antimitotic drugs used for cancer chemotherapy, and the effects of drug combinations also can be monitored. Motility contrast imaging is a potential tissue-based assay platform for highthroughput screening of pharmaceuticals.
Neighboring Elemental Image Exemplar Based Inpainting for Computational Integral Imaging Reconstruction with Partial Occlusion
Ko, Bumseok ; Lee, Byung-Gook ; Lee, Sukho ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 390~396
DOI : 10.3807/JOSK.2015.19.4.390
We propose a partial occlusion removal method for computational integral imaging reconstruction (CIIR) based on the usage of the exemplar based inpainting technique. The proposed method is an improved version of the original linear inpainting based CIIR (LI-CIIR), which uses the inpainting technique to fill in the data missing region. The LI-CIIR shows good results for images which contain objects with smooth surfaces. However, if the object has a textured surface, the result of the LI-CIIR deteriorates, since the linear inpainting cannot recover the textured data in the data missing region well. In this work, we utilize the exemplar based inpainting to fill in the textured data in the data missing region. We call the proposed method the neighboring elemental image exemplar based inpainting (NEI-exemplar inpainting) method, since it uses sources from neighboring elemental images to fill in the data missing region. Furthermore, we also propose an automatic occluding region extraction method based on the use of the mutual constraint using depth estimation (MC-DE) and the level set based bimodal segmentation. Experimental results show the validity of the proposed system.
Calibration of Measurement of Multiple Polarization Singularities
Yu, Renlong ; Xin, Yu ; Zhao, Shuan ; Zhao, Qi ; Chen, Yanru ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 397~402
DOI : 10.3807/JOSK.2015.19.4.397
In this paper, we propose a method used to measure the polarization state of a field with multiple polarization singularities (PSs), such as an array of PSs and PSs in vector speckle. A checkerboard is used to construct characteristic points, which makes it possible to calibrate the mismatches between pictures obtained during the rotation of a quarter-wave plate and a polarizer. Using this method a field with an array of PSs is measured. The experimental result is compared with the numerical simulation. We also carry out some data analysis. The comparison and analysis emphasize the necessity and feasibility of this method to measure the PSs.
Simulation of the Through-Focus Modulation Transfer Functions According to the Change of Spherical Aberration in Pseudophakic Eyes
Kim, Jae-hyung ; Kim, Myoung Joon ; Yoon, Geunyoung ; Kim, Jae Yong ; Tchah, Hungwon ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 403~408
DOI : 10.3807/JOSK.2015.19.4.403
To evaluate the effects of spherical aberration (SA) correction on optical quality in pseudophakic eyes, we simulated the optical quality of the human eye by computation of the modulation transfer function (MTF). We reviewed the medical records of patients who underwent cataract surgery in Asan Medical Center, retrospectively. A Zywave aberrometer was used to measure optical aberrations at 1-12 postoperative months in patients with AR40e intraocular lens implants. The MTF was calculated for a 5 mm pupil from measured wavefront aberrations. The area under the MTF curve (aMTF) was analyzed and the maximal aMTF was calculated while changing the SA (
) and the defocus (-2.0 ~ +2.0 D). Sixty-four eyes in 51 patients were examined. The maximal aMTF was
at a defocus of
with innate SA, and
at a defocus of
when the SA was 0 (full correction of SA). With full SA correction, the aMTF increased in 47 eyes (73.4%; Group 1) and decreased in 17 eyes (26.6%; Group 2). There were statistically significant differences in Z(3, -1) (vertical coma; P = 0.01) and Z(4, 4) (tetrafoil; P = 0.04) between the groups. The maximal aMTF was obtained at an SA of
in Group 1 and an SA of
in Group 2. Optical quality can be improved by full correction of SA in most pseudophakic eyes. However, residual SA might provide benefits in eyes with significant radially asymmetric aberrations.
Optical Design of Multimedia-Embedded LED Dental Astral Lighting using the Reverse Dual Reflector Method
Kwon, Young Hoon ; Hwang, Hyo Chang ; Jun, Hwa Joon ; Kwon, Jin Hyuk ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 409~414
DOI : 10.3807/JOSK.2015.19.4.409
Light-emitting diodes (LED) have many advantages for dental astral lighting because of their high color rendering index (CRI), low power consumption, light weight and longer life. A dental astral lamp is specially designed and simulated for securing the extra space for installing a multimedia display that will be helpful for treating young patients. The optical system using the reverse dual reflection method consisted of four illumination modules disposed at the four corners of the dental astral lamp, and each module comprises a high power LED, an elliptical mirror, and a multifacet reflector assembly using eight cylindrical mirrors. It is shown that the required illuminance, illumination pattern, and the illumination uniformity are well satisfied.
A Novel Calibration Method Research of the Scale Factor for the All-optical Atomic Spin Inertial Measurement Device
Zou, Sheng ; Zhang, Hong ; Chen, Xi-yuan ; Chen, Yao ; Fang, Jian-cheng ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 415~420
DOI : 10.3807/JOSK.2015.19.4.415
A novel method to measure the scale factor for the all-optical atomic spin inertial measurement device (ASIMD) is demonstrated in this paper. The method can realize the calibration of the scale factor by a self-consistent method with small errors in the quiescent state. At first, the matured IMU (inertial measurement unit) device was fixed on an optical platform together with the ASIMD, and it has been used to calibrate the scale factor for the ASIMD. The results show that there were some errors causing the inaccuracy of the experiment. By the comparative analysis of theory and experiment, the ASIMD was unable to keep pace with the IMU. Considering the characteristics of the ASIMD, the mismatch between the driven frequency of the optical platform and the bandwidth of the ASIMD was the major reason. An all-optical atomic spin magnetometer was set up at first. The sensitivity of the magnetometer is ultra-high, and it can be used to detect the magnetization of spin-polarized noble gas. The gyromagnetic ratio of the noble gas is a physical constant, and it has already been measured accurately. So a novel calibration method for scale factor based on the gyromagnetic ratio has been presented. The relevant theoretical analysis and experiments have been implemented. The results showed that the scale factor of the device was
by multi-group experiments with the maximum error value 0.49%.
Design and Verification of Hybrid Optical System for LED Surgical Light
Kwon, Young-Hoon ; Ahn, Sun-Su ; Lee, Seung-Jin ; Kwon, Ki-Jin ;
Journal of the Optical Society of Korea, volume 19, issue 4, 2015, Pages 421~426
DOI : 10.3807/JOSK.2015.19.4.421
This paper presents a hybrid single optical system for an LED surgical light that combines the advantages of both lens- and reflector-type single optical systems. The proposed hybrid single optical system includes a lens in the center and the LED light originating from the lens is redirected using a reflector to achieve a high beam spread. Iterative optical software simulations are used to provide data for the design of the lens and reflector for a single optical system, and for a complex optical system for the LED light assembly. The resulting data is also used to fabricate a prototype system. Experiments using the prototype of the hybrid single optical system and a mock-up LED surgical light confirm the system's shadow dilution performance and its applicability to surgical operations.