• Journal of Korean Vacuum Science & Technology
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• 제6권2호
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• pp.97-100
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• 2002

NaEr(WO$_4$)$_2$ is a new laser material. The planar optical waveguide was formed in NaEr(WO$_4$)$_2$ crystal by 2.6 MeV He$^{+}$ ion implantation at doses of 1.0-1.5 $\times$ 10$^{16}$ ions/cm$^2$ at room temperature. The effective refractive indices of the dark modes were measured using the prism coupling method. foul n modes and five TM modes were observed in the waveguide. The refractive index profiles were analyzed using the reflectivity calculation method (RCM). The influence of heat treatment at moderate temperature on the refractive index profiles of the waveguide was also investigated. We used the TRIM'98 (Transport of ton in Matter) code to simulate the damage profile in the NaEr(WO$_4$) crystal by 2.6 MeV He$^{+}$ion implantation which is helpful for a better understanding of the waveguide formation.ion.

• 대한화학회지
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• 제56권4호
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• pp.424-430
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• 2012

Densities, viscosities, refractive indices and speed of sounds of the binary mixtures of Acetophenone with Ethylchloroacetate were measured over the entire mole fractions at (303.15, 313.15 and 323.15) K. From these experimental results, excess molar volume $V^E$, viscosity deviation ${\Delta}{\eta}$, refractive index deviation ${\Delta}n_D$, deviations in speed of sound ${\Delta}u$, deviations in isentropic compressibility ${\Delta}k_s$ and excess intermolecular free length ${\Delta}L_f$ were calculated. The viscosity data have been correlated with the equations of Grunberg and Nissan, Hind et al., Tamura and Kurata, Katti and Chaudri, Sedgwick, Krishnan-Laddha and McAllister. The thermo physical properties under study were fit to the Jouyban-Acree model. The excess values were correlated using Redlich-Kister polynomial equation to obtain their coefficients and standard deviations. It was found that in all cases, the data obtained fitted with the values correlated by the corresponding models very well. The results are interpreted in terms of molecular interactions occurring in the solution.

• Macromolecular Research
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• 제11권4호
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• pp.236-240
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• 2003

Fabrication of a graded index profile was possible via photochemical reaction of cinnamoyl groups with 350 nm wavelength UV light to form crosslinked structures. Such structural change may induce the change in the refractive index. In order to generate graded index profile in the PMMA polymer optical fiber (POF) with cinnamoyl groups by photochemistry, a methyl methacrylate monomer containing a cinnamoyl functional group in the side chain were prepared. This monomer was then copolymerized with methyl methacrylate with various compositions not only to utilize advantages of poly(methyl methacrylate) but also to overcome the drawbacks of the cinnamate homopolymer. Changes of refractive indices were investigated with various contents of cinnamoyl group and varying irradiation time. Large change in the refractive index (${\Delta}{\approx}0.01$) and its proper profile shape ($g{\approx}2.2$) can be obtained by changing irradiation time.

• 통합자연과학논문집
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• 제2권1호
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• pp.45-49
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• 2009

Electrochemical etching of heavily doped p-type silicon wafers (boron doped, <100> orientation, resistivity; $0.8-1.2m{\Omega}/cm$) with different current density resulting two different refractive indices resulted in DBR (Distributed Bragg Reflectors) porous silicon, which exhibited strong in-plane anisotropy of refractive index (birefringence). Dielectric stacks of birefringent porous silicon acting as distributed Bragg reflectors have two distinct reflection bands depending on the polarization of the incident linearly polarized light. This effect is caused by a three-dimensional (in plane and in depth) variation of the refraction index. Optical characteristics of DBR porous silicon were investigated.

• 한국세라믹학회지
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• 제31권6호
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• pp.601-608
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• 1994

Aluminum oxide thin films were deposited on p-type(100) silicon substrates by electron cyclotron resonance plasma enhanced CVD(ECR-PECVD) using TMA[Al(CH3)3] and oxygen as reactant gases at 16$0^{\circ}C$ or lower temperatures. The aluminum oxide films deposited by ECR-PECVD have the amorphous structure with the refractive index of 1.62~1.64 and the O/Al ratio of 1.6~1.7. Oxygen flow rate necessary for the stable deposition of the aluminum oxide films increases as the deposition temperature increases. It was found from the OES analysis that the ECR plasma had les cooling effect by introducing the TMA reactant gas in comparison with the RF plasma. The properties of aluminum oxide films prepared by ECR-PECVD were compared with those prepared by RF-PECVD. The ECR-PECVD aluminum oxide films have the higher refractive indices, the lower contents of impurities (H and C) and the stronger wet etch resistance than those deposited by RF-PECVD.

• Journal of Information Display
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• 제10권2호
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• pp.72-75
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• 2009

The Brillouin spectrum of 4'-n-pentyl-4-cyano-biphenyl (5CB) liquid crystals homogeneously confined in a planar liquid crystal (LC) cell was measured using a 6-pass tandem Fabry-Perot interferometer. By adopting a special right-angle scattering geometry, the sound velocity of 5CB was estimated from the Brillouin shift without knowing the refractive index. The sound velocity of the longitudinal wave propagating along the direction of the directors aligned parallel to the glass plates of the LC cell was 1784${\pm}$7 m/s at 300 K. The attenuation coefficient $\alpha$ was estimated to be approximately $1.9{\times}10^6m^{-1}$, which is about twice as large as that of the longitudinal sound wave propagating along the direction perpendicular to the directors. The present method may be very useful in the evaluation of the elastic properties of the materials used in display devices, whose refractive indices are not known.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.146-149
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• 1996

Polymerization rate, transmittance, refractive index, and extinction coefficient of plasma polymerized tetramethydisiloxane (TMD) have been investigated. The rate of polymerization of TMD films increased nonlinearly with the discharge lower. The refractive indices of thin films varied from 1.40 to 1.43 and they also increased with increasing discharge power. Also, the extinction coefficient was about 0.2 and is independent of photon energy.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.440-440
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• 2012

The optical characteristics of transparent electrode with various kind of materials and thickness to be used for organic photovoltaic cells were studied by simulation methodology. It demonstrated that the transmittance varies with the kinds of materials, the number of layers and change in the thickness of each layer. In the case of the structure composed of dielectric/Ag/dielectric, optimized transmittance was higher than 90% at 550 nm and the thickness of the Ag layer was ~10nm. Top and bottom dielectric materials can be changed with different refractive index and extinction coefficient. The relation between the optical transmittance of device and transparent electrode with different refractive indices was discussed as well. By processing numerical simulations, an optimized optical transmittance can be obtained by tunning the thickness and materials of transparent electrode.

• 전자공학회논문지D
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• 제34D권6호
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• pp.50-57
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• 1997

TiO$_{2}$ tin films have been grown by MOCVD and their cahracteristics of crystallization and microstructures ahve been invetigated. Envelope mehtods are applied to the analysis of the transmission spectra to obtain the optical constants such as refractive indices and extinction coefficients for the TiO$_{2}$ thin films. The envelope methods are proved to be accurate by simulatin gthe transmission spectra. TiO$_{2}$ thin films start to crystallize at 350.deg.C and then crystallize fully into anatase phase at 400.deg.C or higher temperatures. Activation energies are obtained by plotting the deposition rate with varying the substrate temperature. It is 17.8 kcal/mol for the reaction limited regions. The refractive index and the extinction coefficient of the TiO$_{2}$ thin film at .gamma.=632.8 nm increases from 2.19 to 2.32 and decreases from 0.021 to 0.007, respectively, as the substrate temperature increases from 400 to 600.deg. C.

• 한국표면공학회지
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• 제43권2호
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• pp.97-104
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• 2010

In this paper, we conducted MATLAB simulation using the reflectance formula and the Planck's black body radiation principle, for the purpose of identifying the opimum material and thickness of anti-reflective coating from double layered structures. We found that the optimum condition was obtained when refractive index of upper layer is 1.44 and that of lower layer is 2.29. As materials close to these refractive indices, $MgF_2$ as the upper layer and $HfO_2$, ZnS, $TiO_2$ as the lower layer were suggested. The best result in an average reflectance of 2.759% was obtained from a double layered structure of $MgF_2$ 94 nm/ZnS 55 nm.