Optical and Structural Properties of a Circular Polarization Handedness Inverter Prepared by Using Glancing Angle Deposition

Yong Jun Park,K. M. A. Sobahan,Chang Kwon Hwangbo 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.3

In this paper, we report the optical and the structural properties of a circular polarization handedness inverter consisting of a half-wave plate and a Bragg reflector. The half-wave plate with a zigzag structure and the Bragg reflector with a helical structure were fabricated by using a glancing angle deposition (GLAD) technique. The thin-film half-wave plate with a zigzag structure was found to have the same properties as those of a conventional half-wave plate. The circular polarization handedness inverter was observed to change the circular polarized state of the incident light into the opposite state at the output The structure and the surface morphology of these devices were also investigated by using a scanning electron microscope (SEM). In this paper, we report the optical and the structural properties of a circular polarization handedness inverter consisting of a half-wave plate and a Bragg reflector. The half-wave plate with a zigzag structure and the Bragg reflector with a helical structure were fabricated by using a glancing angle deposition (GLAD) technique. The thin-film half-wave plate with a zigzag structure was found to have the same properties as those of a conventional half-wave plate. The circular polarization handedness inverter was observed to change the circular polarized state of the incident light into the opposite state at the output The structure and the surface morphology of these devices were also investigated by using a scanning electron microscope (SEM).

Effect of Deposition Angle on the Optical and the Structural Properties of Ta2O5 Thin Films Fabricated by Using Glancing Angle Deposition

K. M. A. Sobahan,Yong Jun Park,Chang Kwon Hwangbo 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.3

In this paper, the effect of deposition angle on the optical and the structural properties of Ta2O5 thin films fabricated by using electron beam evaporation with a glancing angle deposition (GLAD) technique is reported. The refractive index and the porosity at various deposition angles are studied. We see that the refractive index decreases and the porosity increases with increasing deposition angle. The calculated in-plane birefringence of GLAD Ta2O5 films shows a maximum value of 0.04 at a deposition angle of 70. The microstructure and the morphology are also investigated by using scanning electron microscope (SEM). The cross-sectional SEM images illustrate a highly oriented microstructure composed of slanted columns and voids due to the shadowing effect and limited adatom diffusion. Therefore, the glancing angle deposition technique is an original way to control the columnar microstructure with an enhanced birefringence. In this paper, the effect of deposition angle on the optical and the structural properties of Ta2O5 thin films fabricated by using electron beam evaporation with a glancing angle deposition (GLAD) technique is reported. The refractive index and the porosity at various deposition angles are studied. We see that the refractive index decreases and the porosity increases with increasing deposition angle. The calculated in-plane birefringence of GLAD Ta2O5 films shows a maximum value of 0.04 at a deposition angle of 70. The microstructure and the morphology are also investigated by using scanning electron microscope (SEM). The cross-sectional SEM images illustrate a highly oriented microstructure composed of slanted columns and voids due to the shadowing effect and limited adatom diffusion. Therefore, the glancing angle deposition technique is an original way to control the columnar microstructure with an enhanced birefringence.

Antireflection Coatings with Helical SiO2 Films Prepared by Using Glancing Angle Deposition

황보창권,박용준,김진주,K. M. A. Sobahan 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.6

We present the optical and the structural properties of helical SiO2 films fabricated by using a glancing angle deposition (GLAD) technique. The relationships among the refractive index, the porosity, the glancing angle, and the substrate rotation speeds of the helical SiO2 films deposited by using GLAD are studied. The results show that the refractive index decreases and the porosity increases with increasing of glancing angle. The refractive index also depends on the substrate’s rotation speed, and it increases as the substrate rotation speed is increased. The minimum refractive index is found to be 1.32 for the helical SiO2 film deposited at a glancing angle of 85˚ with a substrate rotation speed of 0.07 rpm. As an application, a single layer-antireflection (AR) coating is fabricated with a helical SiO2 film based on the deposition conditions in which minimum refractive index was obtained. We found that the average reflectance of the AR coating in the wavelength range of 400 nm to 800 nm was 1.24 %. The structural and surface morphology of these samples were also investigated by using a scanning electron microscope. We present the optical and the structural properties of helical SiO2 films fabricated by using a glancing angle deposition (GLAD) technique. The relationships among the refractive index, the porosity, the glancing angle, and the substrate rotation speeds of the helical SiO2 films deposited by using GLAD are studied. The results show that the refractive index decreases and the porosity increases with increasing of glancing angle. The refractive index also depends on the substrate’s rotation speed, and it increases as the substrate rotation speed is increased. The minimum refractive index is found to be 1.32 for the helical SiO2 film deposited at a glancing angle of 85˚ with a substrate rotation speed of 0.07 rpm. As an application, a single layer-antireflection (AR) coating is fabricated with a helical SiO2 film based on the deposition conditions in which minimum refractive index was obtained. We found that the average reflectance of the AR coating in the wavelength range of 400 nm to 800 nm was 1.24 %. The structural and surface morphology of these samples were also investigated by using a scanning electron microscope.

Influence of Deposition Angle on the Properties of ZrO2 Thin Films Fabricated by Using Oblique Angle Deposition

황보창권,박용준,K M A. Sobahan 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.4

We report the influence of deposition angle on the optical and the structural properties of ZrO2thin films deposited by using electron beam evaporation with oblique angle deposition (OAD). We found that the as-deposited and annealed ZrO2 films grown at an angle of 70。 were all amorphous in nature, which was different from that deposited at normal incidence. The relationships among the refractive index, porosity, and deposition angle were studied. The refractive index was seen to decrease and the porosity to increase with increasing deposition angle. The calculated in-plane birefringence of OAD ZrO2 films had a maximum value of 0.04 at a deposition angle of 70. The microstructure was also investigated by using a scanning electron microscope (SEM).

Optical and Structural Properties of ZnO Thin Films Fabricated by Using Oblique Angle Deposition

박용준,K. M. A. Sobahan,남현정,김진주,황보창권 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.61

In this paper, we report the optical and the structural properties of ZnO thin films deposited by using radio-frequency magnetron sputtering with an oblique angle deposition (OAD) technique. The effect of deposition angle on the refractive index and the in-plane birefringence were studied. With increasing deposition angle, the refractive index decreases, and the in-plane birefringence increases. The in-plane birefringence reaches its maximum value of 0.061 at a deposition angle of 60˚ and then decreases with further increase of the deposition angle. The microstructure and the morphology were also investigated by using a scanning electron microscope (SEM).

Wideband Antireflection Coatings of Porous MgF2 Films by Using Glancing Angle Deposition

Seouk-Hoon Woo,Chang Kwon Hwangbo,Dae-Ho Chang,K. M. A. Sobahan,Yong Jun Park 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.II

In this paper, a new method to design and fabricate a wideband antireflection (AR) coating with a porous MgF$_2$ film by using glancing angle deposition (GLAD) is proposed. Various glancing angles and substrate rotations in GLAD were employed to control the refractive indices and the microstructures of MgF$_2$ films. The relationship between the refractive index and the glancing angle of MgF$_2$ films deposited by using GLAD is investigated. The results show that as the glancing angle is increased from 0$^\circ$ to 80$^\circ$, the porosity of MgF$_2$ films increases due to the shadow effects, and the effective refractive index of MgF$_2$ films drastically decreases from 1.378 to 1.185 at 550 nm. Two-layer wideband AR coatings with porous and dense MgF$_2$ films were also deposited by using GLAD. The results show that the two-layer AR coating has low and wideband reflection for wavelengths between 400 and 1200 nm and that the average reflectance is 0.38 \%. We found that porous MgF$_2$ films deposited by using GLAD at high glancing angles provide very low refractive indices, and so are very useful for wideband AR coatings.

Optical and Structural Properties of ZrO2 Thin Films Fabricated by Using Glancing Angle Deposition

황보창권,박용준,K. M. A. Sobahan 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

In this paper, the optical and the structural properties of ZrO2 thin lms deposited by using electron beam evaporation with a glancing angle deposition (GLAD) technique are presented. The films prepared by using the glancing angle deposition technique were highly oriented structures composed of slanted columns and voids due to the shadow effect and limited adatom diffusion. The relationships among the refractive index, the porosity and the deposition angle were studied. The results show that the refractive index decreases and the porosity increases with increasing deposition angle. The in-plane birefringence of the ZrO2 thin lms was measured and it reached a maximum value of 0.038 at a deposition angle of 70˚. The microstructure and the morphology were also investigated by using a scanning electron microscope (SEM). We found that the optical anisotropy and the microstructure of the ZrO2 thin lms could be controlled by the GLAD technique.

Wavelength-Selective Polarizer Prepared by Using Glancing Angle Deposition

황보창권,박용준,Dae-Ho Chang,K. M. A. Sobahan 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.3

In this paper, the optical and the structural properties of a wavelength-selective polarizer made of narrow band pass filters (NBPFs) are presented. Anisotropic spacer layers were deposited in the NBPFs by using electron beam evaporation with a glancing angle deposition (GLAD) technique while mirror layers were deposited by a conventional evaporation method. TiO2, Ta2O5 and ZrO2 lms deposited by the GLAD technique at various oblique incident angles were investigated to select the right material for the spacer layer. The effects of TiO2 spacer layers with tilted, zigzag and helical structures on the wavelength-selective polarizer were also investigated. It is found that the maximum transmittance peak of the wavelength-selective polarizer with TiO2 zigzag spacer deposited by the GLAD technique is separated by 6 nm due to its birefringence.

Optical and Structural Properties of Helical TiO₂ Films Deposited by Glancing Angle Deposition Technique Technique.

Yong Jun Park,Chang Kwon Hwangbo,K. M. A. Sobahan 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.-

Helical films exhibit the circular Bragg phenomenon and therefore are capable of discriminating between incident plane waves of different circular polarization states. In this paper, optical and structural properties of helical TiO₂ films deposited by glancing angle deposition (GLAD) are presented. The effects of turn numbers, structural handedness, and porosity on the helical TiO₂ films are investigated. It is seen that the selective transmittance of theses films increases as the number of turns increases and the transmittance spectra shift toward longer wavelengths from vacuum to air for both structural handednesses. A helical TiO₂ film with three sections, each of three turns with different pitch thickness, is studied. It shows three Bragg peaks at different wavelengths. The microstructures of these films are also studied by using scanning-electron microscopy. Helical films exhibit the circular Bragg phenomenon and therefore are capable of discriminating between incident plane waves of different circular polarization states. In this paper, optical and structural properties of helical TiO₂ films deposited by glancing angle deposition (GLAD) are presented. The effects of turn numbers, structural handedness, and porosity on the helical TiO₂ films are investigated. It is seen that the selective transmittance of theses films increases as the number of turns increases and the transmittance spectra shift toward longer wavelengths from vacuum to air for both structural handednesses. A helical TiO₂ film with three sections, each of three turns with different pitch thickness, is studied. It shows three Bragg peaks at different wavelengths. The microstructures of these films are also studied by using scanning-electron microscopy.

경사입사 증착방법의 지그재그와 나선형구조를 이용한 편광방향 변환기의 광학적, 물리적 특성

박용준,K M A Sobahan,황보창권 한국진공학회 2008 한국진공학회 학술발표회초록집 Vol.2008 No.8