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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 18, Issue 6 - Dec 2014
Volume 18, Issue 5 - Oct 2014
Volume 18, Issue 4 - Aug 2014
Volume 18, Issue 3 - Jun 2014
Volume 18, Issue 2 - Apr 2014
Volume 18, Issue 1 - Feb 2014
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Dynamics of a Bose-Einstein Condensate on Changing Speeds of an Atomchip Trap Potential
Kim, Seung Jin ; Noh, Jae June ; Kim, Min Seok ; Lee, Jin Seung ; Yu, Hoon ; Kim, Jung Bog ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 633~638
DOI : 10.3807/JOSK.2014.18.6.633
We report experimental behaviors of condensed
atoms responding to changes in the trap potential of the atomchip. The two-types of adiabatic and non-adiabatic overall changes were implemented by changing the ramp-down speed of the chip-wire current, which can dominantly modify the one-axis magnetic field gradient. Under the adiabatic process, a pure condensate stayed in the initial spin state and collectively oscillated with both monopole and dipole modes, while an atomic cloud above the critical temperature exhibited sound waves in a dense ultracold gas. On the other hand, Bose-Einstein condensate atoms with non-adiabatic perturbation were split into spatially different positions by spin states through spin-flip. We investigated the split ratio among spin states depending on final evaporation frequency. Potential changes, of course, cause collective oscillations regardless of the changing process.
Realization of High Speed All-Optical Half Adder and Half Subtractor Using SOA Based Logic Gates
Singh, Simranjit ; Kaler, Rajinder Singh ; Kaur, Rupinder ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 639~645
DOI : 10.3807/JOSK.2014.18.6.639
In this paper, the scheme of a single module for simultaneous operation of all-optical computing circuits, namely half adder and half subtractor, are realized using semiconductor optical amplifier (SOA) based logic gates. Optical XOR gate by employing a SOA based Mach-Zehnder interferometer (MZI) configuration is used to get the sum and difference outputs. A carry signal is generated using a SOA-four wave mixing (FWM) based AND gate, whereas, the borrow is generated by employing the SOA-cross gain modulation (XGM) effect. The obtained results confirm the feasibility of our configuration by proving the good level of quality factor i.e. ~5.5, 9.95 and 12.51 for sum/difference, carry and borrow, respectively at 0 dBm of input power.
Relative Intensity Noise Suppression of Spectrum-Sliced Channels Using Polarization-Independent Optical Modulators
Kim, Hyung Hwan ; Manandhar, Dipen ; Lee, Jae Seung ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 646~649
DOI : 10.3807/JOSK.2014.18.6.646
Performances of spectrum-sliced channels are strongly affected by their relative intensity noise (RIN). We use polarization-independent optical modulators (PIOMs) for spectrum-sliced channels to suppress their RIN. The PIOM driven by a high sinusoidal voltage signal evenly redistributes optical frequency components in the spectral domain and reduces the RIN. It can be used at a broadband light source (BLS) output to produce spectrum-sliced channels having lower RIN values. Also, it can be used for each spectrum-sliced channel within each optical network unit (ONU). In our experiment, where 12.5-GHz-spaced spectrum-sliced channels are used in 1-GbE speed, the use of PIOM at the BLS output reduces the bit error rate (BER) of the spectrum-sliced channel by more than an order of magnitude. The use of PIOM within the ONU reduces the BER by approximately 3 orders of magnitude.
Rigorous Analysis on Ring-Doped-Core Fibers for Generating Cylindrical Vector Beams
Kim, Hyuntai ; Kwon, Youngchul ; Vazquez-Zuniga, Luis Alonso ; Lee, Seung Jong ; Park, Wonil ; Ham, Youngsu ; Song, Suhyung ; Yang, Joong-Hwan ; Jeong, Yoonchan ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 650~656
DOI : 10.3807/JOSK.2014.18.6.650
We propose a novel active fiber design for selectively generating cylindrical vector beams (CVBs) or cylindrical vector modes (CVMs) which can be applied to conventional fiber lasers. A fiber is designed to have a ring-shaped core refractive index profile which can lead to the best overlap between the active dopant distribution profile and the lowest-order CVM (LCVM) field profile. Therefore, the overlap factor (OVF) of the LCVM becomes even higher than that of the fundamental mode. We emphasize that this condition cannot be satisfied by a conventional step-index core fiber (SICF) but by the ring-doped core fiber (RDCF). Because the lasing threshold is inversely proportional to the OVF, the LCVM can predominantly be stimulated even without going through special procedures to impose extra loss mechanisms to the fundamental mode. We numerically verify that the OVF of the LCVM with the doped ions can significantly exceed that of the fundamental mode if the proposed fiber design is applied. In addition, an RDCF of the proposed fiber design can also operate in a regime containing no higher-order modes besides the LCVM, so that it can selectively and efficiently generate the LCVM without being disrupted by the parasitic lasing of the higher-order modes. We highlight that an optimized RDCF can lead to a >30 % higher OVF ratio than a SICF having the same doped area. The proposed model is expected to be useful for enhancing the efficiency of generating CVBs in an all-fiber format.
Simulation and Experimental Validation of Gain-Control Parallel Hybrid Fiber Amplifier
Ali, Mudhafar Hussein ; Abdullah, Fairuz ; Jamaludin, Md. Zaini ; Al-Mansoori, Mohammed Hayder ; Al-Mashhadani, Thamer Fahad ; Abass, Abdulla Khudiar ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 657~662
DOI : 10.3807/JOSK.2014.18.6.657
We demonstrate a simulation of a parallel hybrid fiber amplifier in the C+L-band with a gain controlling technique. A variable optical coupler is used to control the input signal power for both EDFA and RFA branches. The gain spectra of the C+L-band are flattened by optimizing the coupling ratio of the input signal power. In order to enhance the pump conversion efficiency, the EDFA branch was pumped by the residual Raman pump power. A gain bandwidth of 60 nm from 1530 nm to 1590 nm is obtained with large input signal power less than -5 dBm. The gain variation is about 1.06 dB at a small input signal power of -30 dBm, and it is reduced to 0.77 dB at the large input signal power of -5 dBm. The experimental results show close agreement with the simulation results.
Analysis of the LED Lamp Arrangement for Uniformity of Illumination in Indoor VLC System
Hao, Hong-Gang ; Zhang, Dan-Dan ; Tang, Shuai ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 663~671
DOI : 10.3807/JOSK.2014.18.6.663
LED lamp arrangement is a critical issue in indoor visible light communication (VLC) system. In this paper, we analyze the illumination distribution under the arrangement of
and propose a method to find the optimal lamp arrangement. The method, based on the MIMO (Multiple Input/Multiple Output) system model and taking the first order reflection into consideration, enables accurate analysis of the arrangement of the LED lamps for any room. The studies show that under the optimal arrangement the uniformity of illumination is improved from 0.55 to 0.86, which guarantees that users can get almost equal lighting effects, no matter where they locate themselves. At the same time, the RMS delay spread distribution which is used to evaluate the inter-signal-interference (ISI) is analyzed, and the simulation results indicate that the optimal arrangement also can improve the communication quality by reducing the fluctuation of the RMS delay spread.
Estimation of the 3-D Shape Surfaces with Specular Reflections
Kim, Jee Hong ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 672~678
DOI : 10.3807/JOSK.2014.18.6.672
We propose a method to estimate the 3-D shape of surfaces with specular reflection, using a model of the difference in appearance between images reflected from a flat surface and a curved surface. First, we analyze the geometry of spatial reflection from a specular surface and how reflected light varies due to a curved surface. This is used to estimate 3-D shape. The proposed method is shown to be effective in experiments using illumination from spatially distributed light sources and a camera capturing the reflected light from curved, specular surfaces.
Design of Wedge Projection System with Thin Slab Structure
Lee, Taewon ; Choi, Sungwon ; Yang, Yucheol ; Min, Sung-Wook ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 679~684
DOI : 10.3807/JOSK.2014.18.6.679
Enhanced analysis is performed to design a wedge projection system with a slab structure that increases the projected image size. The specification values of the system such as the length of the slab structure and the imaging region are calculated and investigated using an optical simulation tool. We also propose a split imaging region method to represent a large tiled scene using the thin wedge waveguide structure. Experiments are performed to verify the feasibility of the proposed method.
Fabrication of Microholographic Gratings on Al
Grown by Atomic Layer Deposition Using a Femtosecond Laser
Bang, Le Thanh ; Fauzi, Anas ; Heo, Kwan-Jun ; Kim, Sung-Jin ; Kim, Nam ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 685~690
DOI : 10.3807/JOSK.2014.18.6.685
Microholographic gratings were prepared on an aluminum oxide (
) surface using a 140-fs pulse at a center wavelength of 800 nm. The
was deposited on a silicon wafer and on indium tin oxide glass to a thickness of approximately 25 nm using an atomic layer deposition process. The silicon wafer substrate exhibited reflection-type gratings that were measured as a function of the incidence angle. The diffraction efficiency of the fabricated gratings was measured, with a maximum diffraction efficiency of 45% at an incidence angle of approximately
High-Resolution 3-D Refractive Index Tomography and 2-D Synthetic Aperture Imaging of Live Phytoplankton
Lee, SangYun ; Kim, Kyoohyun ; Mubarok, Adam ; Panduwirawan, Adisetyo ; Lee, KyeoReh ; Lee, Shinhwa ; Park, HyunJoo ; Park, YongKeun ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 691~697
DOI : 10.3807/JOSK.2014.18.6.691
Optical measurements of the morphological and biochemical imaging of phytoplankton are presented. Employing quantitative phase imaging techniques, 3-D refractive index maps and high-resolution 2-D quantitative phase images of individual live phytoplankton are simultaneously obtained without exogenous labeling agents. In addition, biochemical information of individual phytoplankton including volume, mass, and density of individual phytoplankton are also quantitatively obtained from the measured refractive index distributions. We expect the present method to become a powerful tool for the study of phytoplankton.
High-Performance Computer-Generated Hologram by Optimized Implementation of Parallel GPGPUs
Lee, Yoon-Hyuk ; Seo, Young-Ho ; Yoo, Ji-Sang ; Kim, Dong-Wook ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 698~705
DOI : 10.3807/JOSK.2014.18.6.698
We propose a new development for calculating a computer-generated hologram (CGH) through the use of multiple general-purpose graphics processing units (GPGPUs). For optimization of the implementation, CGH parallelization, object point tiling, memory selection for object point, hologram tiling, CGMA (compute to global memory access) ratio by block size, and memory mapping were considered. The proposed CGH was equipped with a digital holographic video system consisting of a camera system for capturing images (object points) and CPU/GPGPU software (S/W) for various image processing activities. The proposed system can generate about 37 full HD holograms per second using about 6K object points.
Advanced 360-Degree Integral-Floating Display Using a Hidden Point Removal Operator and a Hexagonal Lens Array
Erdenebat, Munkh-Uchral ; Kwon, Ki-Chul ; Dashdavaa, Erkhembaatar ; Piao, Yan-Ling ; Yoo, Kwan-Hee ; Baasantseren, Ganbat ; Kim, Youngmin ; Kim, Nam ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 706~713
DOI : 10.3807/JOSK.2014.18.6.706
An enhanced 360-degree integral-floating three-dimensional display system using a hexagonal lens array and a hidden point removal operator is proposed. Only the visible points of the chosen three-dimensional point cloud model are detected by the hidden point removal operator for each rotating step of the anamorphic optics system, and elemental image arrays are generated for the detected visible points from the corresponding viewpoint. Each elemental image of the elemental image array is generated by a hexagonal grid, due to being captured through a hexagonal lens array. The hidden point removal operator eliminates the overlap problem of points in front and behind, and the hexagonal lens array captures the elemental image arrays with more accurate approximation, so in the end the quality of the displayed image is improved. In an experiment, an anamorphic-optics-system-based 360-degree integral-floating display with improved image quality is demonstrated.
Projection-Type Integral Imaging Using a Pico-projector
Yang, Yucheol ; Min, Sung-Wook ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 714~719
DOI : 10.3807/JOSK.2014.18.6.714
A pico-projector is a compact and mobile projector that has an infinite focus. We apply the pico-projector to a projection-type integral imaging system, which can expand the image depth to form multiple central depth planes. In a projection-type integral imaging system, the image flipping problem arises because the expanded elemental images pass through a lens array. To solve this problem, we propose the ray tracing of a pico-projector at a central depth plane and compensate the elemental image using a pixel-mapping process. Experiments to verify the proposed method are performed, and the results are presented.
Tolerance Analysis and Compensation Method Using Zernike Polynomial Coefficients of Omni-directional and Fisheye Varifocal Lens
Kim, Jin Woo ; Ryu, Jae Myung ; Kim, Young-Joo ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 720~731
DOI : 10.3807/JOSK.2014.18.6.720
There are many kinds of optical systems to widen a field of view. Fisheye lenses with view angles of 180 degrees and omni-directional systems with the view angles of 360 degrees are recognized as proper systems to widen a field of view. In this study, we proposed a new optical system to overcome drawbacks of conventional omni-directional systems such as a limited field of view in the central area and difficulties in manufacturing. Thus we can eliminate the undesirable reflection components of the omni-directional system and solve the primary drawback of the conventional system. Finally, tolerance analysis using Zernike polynomial coefficients was performed to confirm the productivity of the new optical system. Furthermore, we established a method of optical axis alignment and compensation schemes for the proposed optical system as a result of tolerance analysis. In a sensitivity calculation, we investigated performance degradation due to manufacturing error using Code V(R) macro function. Consequently, we suggested compensation schemes using a lens group decentering. This paper gives a good guidance for the optical design and tolerance analysis including the compensation method in the extremely wide angle system.
Simulation Study on the Effect of the Emitter Orientation and Photonic Crystals on the Outcoupling Efficiency of Organic Light-Emitting Diodes
Lee, Ju Seob ; Ko, Jae-Hyeon ; Park, Jaehoon ; Lee, Jong Wan ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 732~738
DOI : 10.3807/JOSK.2014.18.6.732
Combined optical simulation of the ray-tracing technique and the finite difference time domain method was used to investigate the effect of the emitter orientation and the photonic crystal layer on the outcoupling efficiency (OCE) of bottom-emission type organic light emitting diodes (OLEDs). The OLED with a horizontal emitter exhibited an opposite interference effect to that of one with a vertical emitter, which suggested that the OCE would be very sensitive to the emitter orientation at a fixed emitter-cathode distance. The OLED with a horizontal emitter exhibited much larger OCE than that with a vertical emitter did, which was due to the substantial difference in the radiation pattern along with the different coupling with the surface plasmon excitation. The OCE with a horizontal emitter was increased by approximately 1.3 times by inserting a photonic crystal layer between the indium tin oxide layer and the glass substrate. The present study suggested that appropriate control of the emitter orientation and its combination to other outcoupling structures could be used to enhance the OCE of OLEDs substantially.
Integrated-Optic Electric-Field Sensor Utilizing a Ti:LiNbO
Y-fed Balanced-Bridge Mach-Zehnder Interferometric Modulator With a Segmented Dipole Antenna
Jung, Hongsik ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 739~745
DOI : 10.3807/JOSK.2014.18.6.739
We have demonstrated a
electro-optic electric-field sensor utilizing a
Y-fed balanced-bridge Mach-Zehnder interferometric (YBB-MZI) modulator, which uses a 3-dB directional coupler at the output and has two complementary output waveguides. A dc switching voltage of ~25 V and an extinction ratio of ~12.5 dB are observed at a wavelength of
. For a 20 dBm rf input power, the minimum detectable electric fields are ~8.21, 7.24, and ~13.3 V/m, corresponding to dynamic ranges of ~10, ~12, and ~7 dB at frequencies of 10, 30, and 50 MHz respectively. The sensors exhibit almost linear response for an applied electric-field intensity from 0.29 V/m to 29.8 V/m.
Novel Calibration Method for the Multi-Camera Measurement System
Wang, Xinlei ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 746~752
DOI : 10.3807/JOSK.2014.18.6.746
In a multi-camera measurement system, the determination of the external parameters is one of the vital tasks, referred to as the calibration of the system. In this paper, a new geometrical calibration method, which is based on the theory of the vanishing line, is proposed. Using a planar target with three equally spaced parallel lines, the normal vector of the target plane can be confirmed easily in every camera coordinate system of the measurement system. By moving the target into more than two different positions, the rotation matrix can be determined from related theory, i.e., the expression of the same vector in different coordinate systems. Moreover, the translation matrix can be derived from the known distance between the adjacent parallel lines. In this paper, the main factors effecting the calibration are analyzed. Simulations show that the proposed method achieves robustness and accuracy. Experimental results show that the calibration can reach 1.25 mm with the range about 0.5m. Furthermore, this calibration method also can be used for auto-calibration of the multi-camera mefasurement system as the feature of parallels exists widely.
Enhanced Adhesion and Transmittance Uniformity in Laminated Polymer-Dispersed Liquid Crystal Films
Yoo, Seong-Hyeon ; Park, Min-Kyu ; Park, Ji-Sub ; Kim, Hak-Rin ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 753~761
DOI : 10.3807/JOSK.2014.18.6.753
We propose a two-step UV irradiation procedure to fabricate polymer-dispersed liquid crystal (PDLC) films by lamination. During the first UV treatment, before lamination, the UV-curable monomers coated on one film substrate are solidified through photo-polymerization as the phase separation between the liquid crystals and the monomers. Introducing an adhesion-enhancement layer on the other plastic substrate and controlling the UV irradiation conditions ensure that UV-induced cross-linkable functional groups remain on the surfaces of the photo-polymerized layers. Thereby, the adhesion stability between the top and bottom films is much improved during a second (post-lamination) UV treatment by further UV-induced cross-linking at the interface. Because the adhesion-enhancement and PDLC layers prepared by the bar-coating process are solidified before lamination, the PDLC droplet distribution and the cell gap between the two plastic substrates remain uniform under the lamination pressure. This ensures that the voltage-controlled light transmittance is uniform across the entire sample.
Fabrication of Periodically Poled Lithium Niobate by Direct Laser-Writing and Its Poling Quality Evaluation
Dwivedi, Prashant Povel ; Cha, Myoungsik ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 762~765
DOI : 10.3807/JOSK.2014.18.6.762
We fabricated a periodically poled lithium niobate (PPLN) by direct laser-writing of a quasi-phase-matching (QPM) structure in photolithographic process. Because we do not need to prepare a photomask by electron-beam writing, the "maskless" process shortens the fabrication time and significantly reduces the cost. We evaluated the poling quality of the direct laser-written PPLN by measuring the diffraction noise from the surface relief pattern of the fabricated QPM grating and comparing the results to those from a conventional PPLN made with a photomask. The quality of the PPLN fabricated by direct laser-writing was shown to be equivalent to that fabricated by the conventional method.
Delay Measurement and Split-Step Time-Domain Analysis of Ring Resonator All-Pass Filters
Kim, Hyosuk ; Ko, Yoonyoung ; Moon, Hyunseung ; Kim, Jaeseong ; Chung, Youngchul ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 766~771
DOI : 10.3807/JOSK.2014.18.6.766
Single-ring all-pass filters with various coupling ratios are designed, fabricated, and characterized to assess the validity of the split-step time-domain modeling approach, which is considered for direct simulation of time-domain characteristics, such as optical delay, of various ring resonator devices. When the coupling ratio of the single-ring all-pass filter is 0.4 and 0.8, the delay time is measured to be about 145 and 42 ps respectively, which is comparable to the time-domain modeling results of 151 and 47 ps respectively. The measurements for two- and three-ring all-pass filters are also found to agree quite well with the simulation results. With these results it is confirmed that the split-step time-domain model could be efficiently incorporated into an optical-communication simulation module for ring resonator delay components in an all-optical packet switching system.
Numerical Simulations of the Light-Extraction Efficiency of LEDs on Sapphire Substrates Patterned with Various Polygonal Pyramids
Cui, Hao ; Park, Si-Hyun ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 772~776
DOI : 10.3807/JOSK.2014.18.6.772
We report a numerical analysis of the light-extraction efficiency (LEE) of light-emitting diodes (LEDs) on patterned sapphire substrates (PSSs). We considered various n-sided, regular convex pyramids, where n is an integer and
. We then considered four cross sections: extruded, subtracted, truncated-extruded, and truncated-subtracted. Ray-tracing simulations were carried out with these polygonal pyramid patterns, and the dimensions of the patterns were systematically varied. Optimized pattern shapes were determined for large LEE. An extruded circular pyramid with a slant angle of
was found to be the optimal patterned shape.
An RGB to RGBY Color Conversion Algorithm for Liquid Crystal Display Using RGW Pixel with Two-Field Sequential Driving Method
Hong, Sung-Jin ; Kwon, Oh-Kyong ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 777~782
DOI : 10.3807/JOSK.2014.18.6.777
This paper proposes an RGB to RGBY color conversion algorithm for liquid crystal display (LCD) using RGW pixel structure with two-field (yellow and blue) sequential driving method. The proposed algorithm preserves the hue and saturation of the original color by maintaining the RGB ratio, and it increases the luminance. The performance of the proposed RGBY conversion algorithm is verified using the MATLAB simulation with 24 images of Kodak lossless true color image suite. The simulation results of average color difference CIEDE2000 (
) and scaling factor are 0.99 and 1.89, respectively. These results indicate that the average brightness is increased 1.89 times compared to LCD using conventional RGB pixel structure, without increasing the power consumption and degrading the image quality.
Improved Vertically-Aligned Nematic Mode for High Performance Displays
Jhun, Chul Gyu ; Gwag, Jin Seog ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 783~787
DOI : 10.3807/JOSK.2014.18.6.783
This paper presents an improved vertical alignment nematic liquid crystal mode characterized by the protrusions or slits of the top substrate and additional stripe type common electrodes with polarity switching of the bottom substrate to improve multi-domain vertically aligned (MVA) and patterned vertically aligned (PVA) nematic modes. MVA and PVA modes have disadvantages such as an LC disclination in the vicinity of the middle region of electrodes between the top and bottom protrusions in MVA mode or the top and bottom slits in PVA mode. Therefore, the stripe type common electrode generating a horizontal electric field and the protrusion or slit producing some pretilt of liquid crystals (LCs) were used to improve the LC disclination, which influences the transmittance and response speed. The simulation results showed that the proposed VA mode has higher transmittance than the MVA and PVA modes. As a result, the proposed VA mode can improve the response speed and transmittance remarkably, which makes it useful for upgrading the LCD display quality.
Sub-Micrometer-Sized Spectrometer by Using Plasmonic Tapered Channel-Waveguide
Lee, Da Eun ; Lee, Tae-Woo ; Kwon, Soon-Hong ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 788~792
DOI : 10.3807/JOSK.2014.18.6.788
It has been a critical issue to reduce the size of spectrometers in many fields such as on-chip chemical and biological sensing. The proposed plasmonic channel-waveguide with a sub-micrometer width has a cutoff frequency which enables us to control wavelength dependent propagation properties. We focused on the capability of the waveguide for spectral-to-spatial mapping when the waveguide width changes gradually. In this paper, we propose a plasmonic tapered channel-waveguide structure as a compact spectrometer with a physical size of
. The scattering point just above the tapered waveguide moves linearly depending on the wavelength of the injecting light. The spectral-to-spatial mapping can be improved by increasing the tapered length.
Holographic Reconstruction of Finite Airy Beams with Self-Healed and Multiplexed Features
Choi, Dawoon ; Hong, Keehoon ; Kim, Kyoung-Youm ; Lee, Kyookeun ; Lee, Il-Min ; Lee, Byoungho ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 793~798
DOI : 10.3807/JOSK.2014.18.6.793
To generate finite-power Airy beams, a novel holographic method is proposed. We record the interference pattern between an Airy beam (signal beam) and plane wave (reference beam) on a photopolymer, then decode the hologram by illuminating with the reference beam. The reconstructed beams still present the non-diffraction, acceleration, and self-healing features of optical Airy beams. In addition, angular multiplexing of two Airy beams with opposite acceleration directions is presented.
Directional Radiation of Surface Plasmon Polaritons at Visible Wavelengths through a Nanohole Dimer Optical Antenna Milled in a Gold Film
Janipour, Mohsen ; Hodjat-Kashani, Farrokh ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 799~808
DOI : 10.3807/JOSK.2014.18.6.799
The mechanism of optical interaction of two nanoholes, milled in an opaque gold film, by means of surface plasmon polariton (SPP) propagation is investigated. The interaction depends on the polarization direction of the incident light when the nanohole pair is illuminated through uniform single antenna excitations. It is shown that by illuminating one of the nanoholes, under single antenna excitation, the other nanohole can be excited indirectly via propagated SPPs from the excited nanohole. In addition, it is found that the spectrum of electromagnetic power above the surface of the metallic film at an arbitrary point along the axis of the nanohole pair presents two resonant peaks. These peaks are due to the optical interaction between nanoholes, where the short- and long-wavelength peaks can be assigned to in-phase and antiphase interactions of magnetic dipoles relative to each nanohole, respectively. The magnetic coupled dipole approximation (MCDA) method confirms the simulation results.
A Perceived Contrast Compensation Method Adaptive to Surround Luminance Variation for Mobile Phones
Yang, Cheng ; Zhang, Jianqi ; Zhao, Xiaoming ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 809~817
DOI : 10.3807/JOSK.2014.18.6.809
The loss in contrast-discrimination ability of the human visual system under high ambient illumination level can cause image quality degradation in mobile phones. In this paper, we propose a perceived contrast compensation method by processing the original displayed image. With consideration that the perceived contrast significantly varies across the image, this method extracts the local band contrast from the original image; it then compensates these contrast components to counteract the perceived contrast degradation. Experimental results demonstrate that this method can maintain most contrast details even in high ambient illumination levels.
Erratum : Spectral Reflectivity Recovery from Tristimulus Values using 3D Extrapolation with 3D Interpolation
Kim, Bog G. ; Werner, John S. ; Siminovitch, Michael ; Papamichael, Konstantinos ; Han, Jeongwon ; Park, Soobeen ;
Journal of the Optical Society of Korea, volume 18, issue 6, 2014, Pages 818~818
DOI : 10.3807/JOSK.2014.18.6.818