Dual-comb spectroscopic ellipsometry

• Published in: Nature communications Vol. 8; no. 1; pp. 610 - 8
• Main Authors: Minamikawa, Takeo, Hsieh, Yi-Da, Shibuya, Kyuki, Hase, Eiji, Kaneoka, Yoshiki, Okubo, Sho, Inaba, Hajime, Mizutani, Yasuhiro, Yamamoto, Hirotsugu, Iwata, Tetsuo, Yasui, Takeshi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 20.09.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/1107/527/1989; 639/624/1111/1112; Glass & glassware industry; Humanities and Social Sciences; multidisciplinary; Noise sensitivity; Optical properties; Phase shift; Polarization; Polarization modulation; Polarized light; Science; Science (multidisciplinary); Spectra; Spectral resolution; Spectroellipsometry; Spectroscopy; Spectrum analysis; Stability analysis; Surface mount technology; Thermal instability; Thin films
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-017-00709-y

Spectroscopic ellipsometry is a means of investigating optical and dielectric material responses. Conventional spectroscopic ellipsometry is subject to trade-offs between spectral accuracy, resolution, and measurement time. Polarization modulation has afforded poor performance because of its sensitivity to mechanical vibrational noise, thermal instability, and polarization-wavelength dependency. We combine spectroscopic ellipsometry with dual-comb spectroscopy, namely, dual-comb spectroscopic ellipsometry. Dual-comb spectroscopic ellipsometry (DCSE). DCSE directly and simultaneously obtains the ellipsometric parameters of the amplitude ratio and phase difference between s-polarized and p-polarized light signals with ultra-high spectral resolution and no polarization modulation, beyond the conventional limit. Ellipsometric evaluation without polarization modulation also enhances the stability and robustness of the system. In this study, we construct a polarization-modulation-free DCSE system with a spectral resolution of up to 1.2 × 10 −5  nm throughout the spectral range of 1514–1595 nm and achieved an accuracy of 38.4 nm and a precision of 3.3 nm in the measurement of thin-film samples. Spectroscopic ellipsometry is an established technique to characterize the optical properties of a material. Here, Minamikawa et al. combine the method with dual-comb spectroscopy, which allows them to obtain ellipsometric parameters including the phase difference between s-polarized and p-polarized light.