• Title, Summary, Keyword: Chalcogenide

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The properties of diffraction efficiency in polarization holography using the chalcogenide thin films by the electric field effects. (칼코게나이드 박막에서 전계효과에 의한 편광 홀로그래피 회절효율 특성)

  • 장선주;여철호;박정일;정홍배
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.9
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    • pp.791-795
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    • 2000
  • Amorphous chalcogenide glasses have a wide variety of light-induced effects. In this study, we have investigated the diffraction efficiency of chalcogenide. As$_{40}$ Ge$_{10}$ Se$_{15}$ S$_{35}$ thin films by the various applied electric fields. The holographic grating in these thin films has been formed using a linearly polarized He-Ne laser light (633nm). The diffraction efficiency was investigated the two method of applied electric field in the perpendicular and parallel to the direction of inducing beam. We obtained that properties of diffraction efficiency in the two methods of applied electric field. The result is shown that the diffraction efficiency of parallel electric field is 285% increase, η=1.1$\times$10$^{-3}$ and the diffraction efficiency of perpendicular electric field is 80% decrease, η=9.83$\times$10$^{-5}$ . Also, we have investigated the anisotropy property on chalcogenide thin films by the electric field effects.

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Preparation and Characterization of $Ge_{20}As_{20}Se_{60}$ Amorphous Chalcogenide Thin Film by Spin Coating (Spin-coating에 의한 $Ge_{20}As_{20}Se_{60}$ 비정질 chalcogenide 박막의 제조 및 광특성 분석)

  • 이강구;최세영
    • Journal of the Korean Ceramic Society
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    • v.37 no.3
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    • pp.219-226
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    • 2000
  • Amorphous Ge20As20Se60 chalcogenide thin films were prepared by spin coating technique from mixed solutions of As40Se60 and Ge40Se60 dissolved in ethylenediamine. Films were prepared at a roating speed of 3500 rpm and spinning time was 10 second and heat-treateed at 27$0^{\circ}C$ for 1 hour. The resulting film thickness and RMS roughness were approximately 340 nm and 15$\AA$. Photostructure changes were investigated with 514.5nm Ar+ laser irradiation and heat-treatment. After Ar+ laser irradiation, transmittance and transmission efficiency decreased respectively up to 24.9% at 2.43 eV and 67.5% at 3.27 eV, and absorption edge shifted toward long wavelength. Optical bandgap changed from 2.03 to 1.83 eV, and absoprtion coefficient and absorption efficiency increased up to 0.33$\times$105cm-1 at 3.37eV and 88.3% at 1.31 eV, respectively. These photodarkening state were recovered reversibly by heat-treatment at 27$0^{\circ}C$ for 1 hour. Photodarkening and thermal bleaching effects by laser irradiation and heat-treatment revealed reversible amorphous-to-amorphous transition varying only coordination number.

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Analysis of noise rejection of stored holographic digital data on the chalcogenide thin film (칼코게나이드 박막에 저장된 홀로그래픽 디지털 정보의 잡음 제거에 관한 연구)

  • Lim, Byoung-Rock;Lee, Woo-Sung;Ahn, Kwang-Seop;Yeo, Cheol-Ho;Chung, Hong-Bay
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.479-480
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    • 2005
  • The Analog data is impossible to perfect reconstruct original data at a hologram data storage because of noise such as cross talk. So it is necessary that data can be stored by digital signal unavoidably. Therefore this work deals with experiments from this point of view through writing & reading of digital data. We stored 256bit digital data at one point on As-Ge-Se-S chalcogenide thin film and we reconstruct original data of 100% through the specified algorithm such as the histogram equalization, the interactive correction, etc. This result shows that the data is able to reconstruct under relative low diffraction efficiency. As the result, we expect the possibility of chalcogenide thin film for HDDS as the analysis of the effective resolution refer to reconstruction rate and diffraction efficiency.

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Holographic Data Grating formation of Ag/AsGeSeS thin films (Ag/AsGeSeS 박막의 홀로그래픽 데이터 격자 형성)

  • Yeo, Cheol-Ho;Lee, Ki-Nam;Kyoung, Shin;Lee, Young-Jong;Chung, Hong-Bay
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.92-95
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    • 2005
  • The silver photodoping effect in amorphous AsGeSeS chalcogenide thin films for holographic recording has been investigated using a HeNe laser ($\lambda$=632.8 nm). The chalcogenide films prepared in this work were thinner in comparison with the penetration depth of recording light ($d_p$=1.66 mm). The variation of the diffraction efficiency $(\eta)$ in amorphous chalcogende films exhibits a tendency, independently of the Ag photodoping. That is, n increases relatively rapidly at the beginning of the recording process, reaches the maximum $({\eta}_{max})$ and slowly decreases. In addition, the value of ${\eta}_{max}$ depends strongly on chalcogenide film thickness(d) and its peak among the films with d = 40, 80, 150, 300, and 633 nm is observed at d = 150 nm (approximately 1/2n), where n is refractive index of the chalcogenide (n=2.0). The ${\eta}$ is largely enhanced by Ag photodoping into the chalcogenides. In particular, the value of hmax in a bilayer of 10-nm-thick Ag/150-nm-thick AsGeSeS film is about 1.6%, which corresponds to ~20 times in comparison with that of the AsGeSeS film (without Ag).

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The Photoinduced Birefringence of Chalcogenide Thin Film by the Ag Polarized-photodoping (Ag 편광-광도핑에 의한 칼코게이나이드 박막의 광유기 복굴절)

  • 장선주;박종화;박정일;정홍배
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.2
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    • pp.139-144
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    • 2001
  • In this study, we have investigated the photoinduced birefringence of Ag plarized-photodoping in double-layer of Ag doped chalcognide thin films and dependence of polarization states in chalcogenide thin films. Also, we have investigated the polarization dependence of photoinduced birefringence and the anisotropy of absorption in an amorphous As$\sub$40/Ge$\sub$10/Se$\sub$15/S$\sub$35/ chalcogenide thin films using two 632.8nm He-Ne lasers, which have a smaller energy than the optical energy gap (E$\sub$OP/) of the film, i.e., an exposure of sub-bandgap light (hν$\sub$op/). The photoinduced phenomena of Ag polarized-photodooping increasing the linear dichroism(d), about 84% and birefringence(Δn), about 23%. It will offer lots of information for the photodoping mechanism and analysis of chalcogenide thin films.

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Controlled Crystallization and its Effects on Some Properties of Ge-Se-Te Chalcogenide Glass (Ge-Se-Te계 Chalcogenide 유리의 결정화 및 결정화가 물성에 미치는 영향)

  • 송순모;최세영;이용근
    • Journal of the Korean Ceramic Society
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    • v.33 no.8
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    • pp.855-862
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    • 1996
  • The nucleation and the crystal growth rates of Ge-Se-Te chalcogenide glass by two step heat-treatment and its effect on the mechanical optical properties and water-resistance were determined. The maximum nuclea-tion and crystal growth rate were 2.1$\times$103/mm3 .min at 28$0^{\circ}C$ and 0.4${\mu}{\textrm}{m}$/min at 33$0^{\circ}C$ respectively. When the crystal volume fraction with crystal size $1.5mutextrm{m}$ was about 4% the (hardness and fracture toughness were about 117kg/mm2 and 6.0 MPa.mm1/2)respectively. The weight loss of crystallized glass in water was lower than parent glass($25^{\circ}C$ for 32 hrs : 0.03% 8$0^{\circ}C$ for 16 hrs : 0.1%) as 0.01% at $25^{\circ}C$, 0.03% at 8$0^{\circ}C$ for 16 hrs : 0.1%) at $25^{\circ}C$ 0.03% at 8$0^{\circ}C$ respectively. The IR-transmittance decreased with increasing crystal size and crystal volume fraction. The IR-transmittance of crystallized glass with the crystal size of $1.5mutextrm{m}$ (crystal volume fraction : 4%) presented 56% which was about 4% lower than that of parent glass.

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Molding and Evaluation of Ultra-Precision Chalcogenide-Glass Lens for Thermal Imaging Camera Using Thermal Deformation Compensation (열변형 보정을 통한 열화상카메라용 초정밀 칼코지나이드 유리렌즈 몰드성형 및 특성 평가)

  • Cha, Du Hwan;Kim, Jeong-Ho;Kim, Hye-Jeong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.2
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    • pp.91-96
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    • 2014
  • Aspheric lenses used in the thermal imaging are typically fabricated using expensive single-crystal materials (Ge and ZnS, etc.) by the costly single point diamond turning (SPDT) process. As a potential solution to reduce cost, compression molding method using chalcogenide glass has been attracted to fabricate IR optic. Thermal deformation of a molded lens should be compensated to fabricate chalcogenide aspheric lens with form accuracy of the submicron-order. The thermal deformation phenomenon of molded lens was analyzed ant then compensation using mold iteration process is followed to fabricate the high accuracy optic. Consequently, it is obvious that compensation of thermal deformation is critical and useful enough to be adopted to fabricate the lens by molding method.