• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.8
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• pp.736-739
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• 2003

We prepared the chalcogenide As$\_$40/Ge$\_$10/Se$\_$15/S$\_$35/, Se$\_$75/Ge$\_$25/ thin film. Holographic grating was formed by the He-Ne laser( λ =633 nm). Annealing at 100$^{\circ}C$ and 200$^{\circ}C$ has been used to change the optical property of chalcogenide thin films for holographic grating formation. As the results, large variation of the optical property was generated at the As$\_$40/Ge$\_$10/Se$\_$15/S$\_$35/ chalcogenide film. Diffraction efficiency of the As$\_$40/Ge$\_$10/Se$\_$15/S$\_$35/ film has been enhanced about three times

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.312-315
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• 2000

In this study, we have investigated the holography recording and reconstruction of the polarization state in chalcogenide $A_{s40}Ge_{10}Se_{15}S_{35}4 thin films using a He-Ne laser light(633nm). The thickness of thin films is a 8677${\AA}$ and 9093${\AA}$. A He-Ne laser used to probe and record of the grating. Also the polarization state of object beam modulated with a $\lambda/4$ wave plate. The polarization state of the +lst order diffracted beam generated by readout of the grating with a linearly polarized reference beam. It was the same-handed polarization state as the polarization state of the recording beam. The diffraction efficiency of circularly polarized recording represented higher than other polarization state.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.47-50
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• 1987

There are various holographic recording materials, such as Dichromated Gelatin, Silver Halide, Thermoplastic, Photoresist. In this paper especially, we used Photoresist to make the phase holographic grating. Deep-groove diffractive grating formed in relatively thin holographic recording material is to express high diffraction efficiency. Phase holographic grating recorded In photoresist can be used very practical because it has the high diffraction efficiency, and it is possible to make a replication easily. So, it has the merit in recording the optical holographic grating than any other materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.820-823
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• 2000

In this study, we have investigated the holography recording and reconstruction of the polarization state in chalcogenide $As_{40}$$Ge_{10}$$Se_{15}$$S_{35}$ thin films using a He-Ne laser light(633nm). The thickness of thin films is a 8677${\AA}$ and 9093${\AA}$. A He-Ne laser used to probe and record of the grating. Also the, polarization state of object beam modulated with a $\lambda/4$ wave plate. The polarization state of the +1st order diffracted beam generated by readout of the grating with a linearly polarized reference beam. It was the same-handed polarization state as the polarization state of the recording beam. The diffraction efficiency of circularly polarized recording represented higher than other polarization state.

• Macromolecular Research
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• v.17 no.11
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• pp.874-878
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• 2009

Photorefractive polymer composites were synthesized based on poly (N-vinylcazbazole) (PVK) doped with liquid nonlinear optical chromophores and a sensitizer $C_{60}$. PVK/liquid NLO chromophores/$C_{60}$ devices showed no signs of phase separation and did not require a plasticizer, such as ethylcarbazole. The composites showed 69% diffraction efficiency (C3) and a rapid response time of 46 ms (C1) in four-wave mixing experiments at a light intensity of $60\;mW/cm^2$ and a wavelength of 633 nm.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.279-280
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• 2007

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.939-942
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• 2002

The optically addressed and electrically addressed spatial phase only light modulators without pixelized structures have been developed. A sufficient phase modulation capability and a high diffraction efficiency of these devices are useful for practical applications.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.76-77
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• 2004

• Journal of Broadcast Engineering
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• v.20 no.6
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• pp.807-817
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• 2015

This paper is to propose an encryption method for only an allowed user to see the content for a digital hologram, that is a high value-added content. This paper uses a characteristic of Fresnel transform that the object region is concentrated to a relatively small part of the diffraction plane. By encrypting the concentrated part only the region to be encrypted and in turn the amount of data to be encrypted is reduced a lot, which results in an high efficiency with low encryption rate. As the methodology, a digital hologram is first Fresnel transformed for reconstruction and the result is secondly Fresnel transformed to concentrate the energy into the center of the diffraction plane to encrypt the concentrated region only. For the 2nd transform, energy concentration degree is determined by adjusting the diffraction distance and encryption strength is determined by adjusting the scaling factor. For this we analyze the optimal encryption area according to the diffraction distance and the scaling factor. When applying the proposed method with diffraction distance of 20m the object information was visually unrecognizable with the encryption ratio only 0.005% ~ 0.02%.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.163.1-163.1
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• 2016

Lead halide perovskites CH3NH3PbX3 (X=Cl, Br, I) have received great interest in the past few years because of their excellent photoelectronic properties as well as their low-cost solution process. Their theoretical efficiency limit of the solar cell devices was predicted around 31% by a detailed balance model for the reason that exceptional light-harvesting and superior carrier transport properties. Additionally, these excellent properties contribute to the applications of optoelectronic devices such as LASERs, LEDs, and photodetectors. Since these devices are mainly using perovskite thin film, one of the most important factor to decide the efficiency of these applications is the quality of the film. Even though, optoelectrical devices are composed of polycrystalline thin film in general, not a single crystalline form which has longer carrier diffusion length and lower trap density. For these reasons, monodomain perovskite thin films have potential to elicit an optimized device efficiency. In this study, we analyzed the crystallography of the in-plane aligned perovskite thin film by X-ray diffraction (XRD) and selected area electron diffraction (SAED). Also the basic optic properties of perovskites were checked using scanning electron microscopy (SEM) and UV-Vis spectrum. From this work, the perovskite which is aligned in all directions both of out-of-plane and in-plane was fabricated and analyzed.