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Thin film display based on polymer waveguides.
Park, Suntak,Park, Bong Je,Yun, Sungryul,Nam, Saekwang,Park, Seung Koo,Kyung, Ki-Uk Optical Society of America 2014 Optics express Vol.22 No.19
<P>This paper reports thin, transparent, and soft displays based on polymer waveguides that are compliant with curvilinear interfaces. In order to prove a feasibility of optical waveguide for a flexible display, we suggest the waveguide fabricated by a multi-step lithography process using two photo-curable pre-polymers with different refractive index. The displays are composed of light sources, polymer waveguides, and scatter patterns. The light signal propagating through the waveguides forms images of the scatter patterns by deflecting the light signals to outer surface. The scatter patterns are configured to a seven-segment. The seven-segment design with a switching methodology of the light sources contributes to selectively representing all decimal numbers from 0 to 9 by combination of activated segments. For a large area display based on the proposed methodology, a single light source interconnected to multi-waveguide section is integrated with a QWERTY key pad design. The display shows high transparency and flexibility without visual distortion.</P>
A variation in wrinkle structures of UV-cured films with chemical structures of prepolymers
Park, Seung Koo,Kwark, Young-Je,Nam, Saekwang,Moon, Jaehyun,Kim, Dong Wook,Park, Suntak,Park, Bongje,Yun, Sungryul,Lee, Jeong-Ik,Yu, Byounggon,Kyung, Ki-Uk Elsevier 2017 Materials letters Vol.199 No.-
<P>Spontaneously wrinkled films can be easily obtained from UV-crosslinkable liquid prepolymers under special UV-curing conditions. They vary wrinkle structures of the UV-cured films and, however, cannot be precisely controlled. Here, five different UV-crosslinkable prepolymers are synthesized to study the chemical structure effect of prepolymers on wrinkle formation and modulation of the UV-cured films irrespective of the UV-curing conditions. Both wavelength and amplitude of the wrinkles are tuned with the different liquid prepolymers from 4.10 to 5.63 mu m and from 1.00 to 1.66 mu m, respectively. The wrinkle structures of the UV-cured films are faded by adding a solid prepolymer to a liquid prepolymer due to interference from it in the shrinkage of the liquid prepolymer layer. The wrinkles completely disappear in the UV-cured films fabricated from the formulated prepolymers containing over 50 wt% of the solid prepolymer. (C) 2017 Elsevier B.V. All rights reserved.</P>
Sub-dB/cm propagation loss in silver stripe waveguides
Park, Suntak,Ju, Jung Jin,Kim, Jin Tae,Kim, Min-su,Park, Seung Koo,Lee, Jong-Moo,Lee, Wook-Jae,Lee, Myung-Hyun The Optical Society 2009 Optics express Vol.17 No.2
<P>We demonstrate sub-dB/cm propagation losses in polymer-based silver stripe waveguides at the wavelength of 1.31 microm. The silver stripe waveguides were fabricated in a low-loss fluorinated polymer clad. To form uniform metal stripe patterns, which are essential for reducing propagation loss, we developed a lift-off process using double layers of photoresist and SiNx. A propagation loss of less than 1.0 dB/cm was obtained with the 11- nm-thick silver stripes in the width range of 1.5 - 4.5 microm. A coupling loss of approximately 1.0 dB with a polarization maintaining single mode fiber was achieved for a width of 4.5 microm. For a width of 2.0 microm, we recorded a minimum propagation loss of 0.4 dB/cm, which is comparable with that of dielectric multi-mode waveguides.</P>
Grating-Assisted Emission of Surface Plasmons
Suntak Park,Seok Ho Song,오차환,Gwansu Lee,Hyong Sik Won,Pill-Soo Kim 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.2
We investigate the coupling of surface plasmons with diraction grating structures. As a diffraction theory to analyze the coupling characteristics, a rigorous coupled-wave theory is introduced. The emission of surface plasmons from dielectric grating structures is evaluated in detail by varying the thickness of the grating layer and the metal layer, as well as the period of the grating layer. Calculations show that the diffraction eciency could be larger than 55 % and that the conversion eciency of the diffracted light from surface plasmons could reach 80 %. We also fnd that the incident angle for a re ection minimum is different from the angle for a diraction maximum.
박선택(Suntak Park),김필수(Pill Soo Kim),오차환(Cha Hwan Oh),송석호(Seok Ho Song) 한국광학회 1997 한국광학회지 Vol.8 No.2
푸리에 변환의 일반형인 분수차 푸리에 변환(fractional Fourier transform : FRT)을 근간으로 하는 분수차 상관기는 입력패턴의 위치나 모양에 따라 상관결과치가 변하는 공간 가변 특성을 갖는다. 이러한 특성을 갖는 분수차 상관기를 푸리에 변환을 이용하는 기존의 상관기와 비교하였고, 분수차에 따른 상관결과치의 변화를 분석하였다. 정확한 분수차 상관함수의 계산을 위하여 광학부품들의 정렬에 있어서 고도의 정확도와 안정도를 갖는 평판 집적 광학계를 구성하였으며, 실험결과와 계산결과를 비교함으로써 평판 집적 광학계에 의한 분수차 상관기의 구현이 매우 정확히 수행될 수 있음을 검증하였다. On the base of the fractional Fourier transform(FRT) which is known as a generalized form of the conventional Fourier transform, the fractional correlation has been implemented. Shift-variance property of the fraction correlation has been evaluated and compared with the shift-invariance of the conventional correlation. The fractional correlation operation has been implemented by using a planar optics configuration which integrates all of the optical components on a single glass substrate. A good agreement between the experimental and calculated results has been obtained.
Polymer-Based Flexible Visuo-Haptic Display
Sungryul Yun,Suntak Park,Bongjae Park,Seung Koo Park,Prahlad, Harsha,Von Guggenberg, Philip,Ki-Uk Kyung IEEE 2014 IEEE/ASME transactions on mechatronics Vol.19 No.4
<P>We report a flexible visuo-haptic display that allows for interactive haptic feedback on the visual display. The visuo-haptic display is fabricated by integrating a dielectric elastomer (DE) based thin film actuator array into a flexible display and pressure sensors. The DE actuator array consists of nine active cells, which generate thickness-mode deformation in response to voltage signal. The flexible display presents images of the aligned three alphabet characters at each section in 3 × 3 matrix during light propagation via optical multiwaveguide. The pressure sensors are placed on the bottom of the DE actuator array for haptic feedback. The performance of the DE actuators is proved to be capable of realizing sufficient vibro-tactile sensation in the perceivable range of human touch sense. The integrated system enables the visual display to provide interactive haptic feedback such as key pressing, contact vibration sensations, etc., in accordance with user input.</P>
Ju, Jung Jin,Park, Suntak,Kim, Min-su,Kim, Jin Tae,Park, Seung Koo,Park, Yoon Jung,Lee, Myung-Hyun IEEE 2008 Journal of lightwave technology Vol.26 No.11
<P> We present characteristics of very thin Au strip waveguides based on long-range surface plasmon polaritons (LR-SPPs) along thin Au strips embedded in polymers. We also report a 10 Gbps optical signal transmission via LR-SPPs with the pig-tailed Au strip waveguide at a telecommunication wavelength of 1.55 <TEX>$\mu{\hbox {m}}$</TEX>. We limited the thickness, width, and length up to <TEX>$\sim$</TEX>20nm, <TEX>$\sim {\hbox {10}}\ \mu{\hbox {m}}$</TEX>, and <TEX>$\sim$</TEX>5 cm, respectively, for practical applications. At 1.55 <TEX>$\mu{\hbox {m}}$</TEX>, loss properties of the Au strip waveguides were theoretically and experimentally evaluated with thickness, width and cladding material. The lowest propagation loss of <TEX>$\sim$</TEX>1.4dB/cm was experimentally obtained with the 14-nm-thick and 2- <TEX>$\mu{\hbox {m}}$</TEX>-wide Au strip. With a single-mode fiber, the lowest coupling loss of less than 0.1 dB/facet was achieved with the 14-nm-thick and 7.5-<TEX>$\mu{\hbox {m}}$</TEX>-wide Au strip. The lowest insertion loss was obtained 7.7dB with the 14-nm-thick, 5-<TEX>$\mu{\hbox {m}}$</TEX>-wide, and 1.5-cm-long Au strip. The propagation loss was improved approximately 30% for the 17-nm-thick Au strip with lowering the refractive index of the cladding polymer by 0.01. In the 10 Gbps optical signal transmission experiment, the LR-SPP waveguide exhibits an excellent eye opening and a 2.2 dB power penalty at <TEX>$10^{-12}$</TEX> bit error rate. These all results indicate that the LR-SPP waveguide is a potential transmission line for optical interconnects to overcome inherent problems in electric interconnects. </P>