Investigation of the Light Reflection from Dielectric Thin Films Coated on Substrates

Deok Woo Kim, Jiung Kim, Byoung Joo Kim, Myoungsik Cha

doi:10.3807/KJOP.2020.31.6.321

All Issue

2020 Vol.31, Issue 6 Preview Page Next Page

Regular Paper

Investigation of the Light Reflection from Dielectric Thin Films Coated on Substrates 기판 위에 입혀진 유전체 박막의 빛 반사에 관한 연구

25 December 2020. pp. 321-327

PDF XML

Abstract

기판 위에 코팅된 박막의 빛 반사 특성에 대해 연구하였다. 입사 매질로 굴절률이 큰 프리즘을 사용하여 박막/기판 계의 내부 전반사 현상과 공기/박막/기판 계가 이루는 도파로로 빛이 결합되어 들어가는 현상을 종합적으로 비교, 연구하였다. 박막의 굴절률이 기판의 굴절률보다 큰 경우에는 빛의 입사각을 증가시켜 나가면 먼저 기판에 의한 전반사가 일어나고, 그 이후 도파로 모드를 맞추는 좁은 각 영역에서 반사율이 떨어지는 현상을 볼 수 있으며, 이것을 이용하여 박막의 굴절률과 두께를 정확히 측정할 수 있다. 반면에 박막의 굴절률이 기판의 굴절률보다 작은 경우에는 도파로 모드가 존재하지 않는다. 이 경우 덩어리 매질에서처럼 뚜렷하지는 않지만 박막에 의한 전반사가 간섭무늬를 동반하여 나타난다. 본 연구에서는 프리즘/박막/기판 구조에서 일어나는 반사 현상을 전반적으로 관측하고 분석하여, 두 경우 모두 박막의 굴절률을 측정할 수 있는 가능성을 조사하였다.

키워드

박막

내부 전반사

간섭무늬

We investigated the light reflection from thin films coated on substrates. Using a prism with a high refractive index as the incident medium, the phenomena of the total internal reflection (TIR) of the prism/film/substrate system and the light coupling into the optical waveguide formed by the air/film/substrate system were comprehensively studied and compared. If the refractive index of the thin film is greater than that of the substrate, within the TIR region of the substrate, sharp reflection minima occur at specific angles where the waveguide modes are excited, that can be used to accurately measure the refractive index and thickness of a thin film. On the other hand, if the refractive index of the thin film is smaller than that of the substrate, such waveguide modes do not exist. In this case, although not so distinct as a bulk medium, the TIR effect of the thin film is still observable, accompanied by an interference pattern. In this study we analyzed the overall reflection phenomena occurring from prism/film/substrate structures, to investigate the possibility of measuring the refractive index of a thin film in both cases.

Keywords

Thin film

Total internal reflection

Interference fringe

References

T. Tamir, Integrated Optics (Topics in Applied Physics Series Vol. 7), 2nd ed. (Springer, Berlin, Germany, 1979), pp. 83-93.

H. Osterberg and L. W. Smith, "Transmission of optical energy along surfaces: Part I, homogeneous Media," J. Opt. Soc. Am. 54, 1073-1078 (1964). 10.1364/JOSA.54.001073

R. Ulrich and R. Torge, "Measurement of thin film parameters with a prism coupler," Appl. Opt. 12, 2901-2908 (1973). 10.1364/AO.12.00290120125894

M. L. Dakss, L. Kuhn, P. F. Heidrich, and B. A. Scott, "Grating coupler for efficient excitation of optical guided waves in thin films," Appl. Phys. Lett. 16, 523-525 (1970). 10.1063/1.1653091

J. D. Jackson, Classical Electrodynamics, 3rd ed. (John Wiley & Sons, 1998), Chapter 7.

J. Kim, "Enhanced third harmonic generation in organic multilayers," Ph. D. Thesis, Department of Physics, Pusan National University (2019), Chapter 4. 10.1364/CLEOPR.2018.W2B.6

F. L. McCrackin, E. Passaglia, R. R. Stromberg, and H. L. Steinberg, "Measurement of the thickness and refractive index of very thin films and the optical properties of surfaces by ellipsometry," J. Res. Natl. Bur. Stand. A. Phys. Chem. 67A, 363-377 (1963). 10.6028/jres.067A.04031580576

H. J. Choi, "Measurement of refractive index of wafer-type medium and generation of optical third harmonic," Master Thesis, Department of Physics, Pusan National University (2010), Chapter 4.

R. A. Paselk, The Evolution of the Abbe Refractometer (Humboldt, Published Date: Sep. 1999), https://www2.humboldt.edu/scimus/Essays/EvolAbbeRef/EvolAbbeRef.htm (Accessed Date: 3 Nov. 2020)

R. E. Anderson and A. J. Lightman, "Measurements of the refractive-index variations with temperature of a photomonomer," Appl. Opt. 30, 3792-3793 (1991). 10.1364/AO.30.00379220706462

Q. W. Song, C.-Y. Ku, C. Zhang, R. B. Gross, R. R. Birge, and R. Michalak, "Modified critical angle method for measuring the refractive index of bio-optical materials and its application to bacteriorhodopsin," J. Opt. Soc. Am. B 12, 797-803 (1995). 10.1364/JOSAB.12.000797

H. Li and S. Xie, "Measurement method of the refractive index of biotissue by total internal reflection," Appl. Opt. 35, 1793-1795 (1996). 10.1364/AO.35.00179321085303

P. D. Maker, R. W. Terhune, M, Nisenoff, and M. Savage, "Effects of dispersion and focusing on the production of optical harmonics," Phys. Rev. Lett. 8, 21-22 (1962). 10.1103/PhysRevLett.8.21

J. Kim, C. S. S. P. Kumar, M. Cha, H. Choi, K.-J. Kim, and N. Peyghambarian, "Quasi-phase-matched third harmonic generation in organic multilayers," Sci. Rep. 8, 16419 (2018). 10.1038/s41598-018-34788-830401913

F. L. Pedrotti and L. S. Pedrotti, Introduction to Optics, 2nd ed. (Prentice-Hall International, NJ, USA. 1993), pp. 184-188.

O. S. Heavens, "Optical properties of thin films," Rep. Prog. Phys. 23, 1 (1960). 10.1088/0034-4885/23/1/301

B. Son, H. Choi, J. E. Park, and M. Cha, "A study of the phase relations between the reflected and transmitted light waves at a beam splitter and their application to interferometers," Korean J. Opt. Photon. 26, 103-109 (2015). 10.3807/KJOP.2015.26.2.103

M. S. Kwon, "Measurement of refractive index of flat optical material by critical angle method," Master Thesis, Department of Physics, Pusan National University (2008), Chapter 3.

J. A. Stone and J. H. Zimmerman, Index of Refraction of Air (Engineering Metrology Toolbox), https://emtoolbox.nist.gov/Wavelength/Edlen.asp (Accessed Date: 3 Nov. 2020)

Information

Publisher :Optical Society of Korea
Publisher(Ko) :한국광학회
Journal Title :Korean Journal of Optics and Photonics
Journal Title(Ko) :한국광학회지
Volume : 31
No :6
Pages :321-327
Received Date :2020. 09. 25
Revised Date :2020. 10. 19
Accepted Date : 2020. 10. 19
DOI :https://doi.org/10.3807/KJOP.2020.31.6.321

Korean Journal of Optics and Photonics ISSN:1225-6285(Print) 2287-321X(Online) 한국광학회지

All Issue