Noise analysis in THz time-domain spectroscopy and accuracy enhancement of optical constant determination

Lionel Duvillaret; Frederic Garet; Jean-Louis Coutaz

doi:10.1117/12.347129

29 April 1999 Noise analysis in THz time-domain spectroscopy and accuracy enhancement of optical constant determination

Lionel Duvillaret, Frederic Garet, Jean-Louis Coutaz

Proceedings Volume 3617, Terahertz Spectroscopy and Applications; (1999) https://doi.org/10.1117/12.347129
Event: Optoelectronics '99 - Integrated Optoelectronic Devices, 1999, San Jose, CA, United States

Abstract

THz time-domain spectroscopy is a powerful and fast technique for measuring the optical constants of materials over a wide frequency range. In this paper, we analyze the weight of the different error terms on the optical constants determination. The different sources of noise are taken into account in a phenomenological way and the noise power can be expressed as a second order polynomial function of the complex transmission coefficient modulus (rho) of the sample under test. Then, for given experimental conditions, the accuracy on the optical constants determination depends on (rho) . In the case of optically thick sample, the echoes of the THz pulse, caused by multiple reflections into the sample, are temporally well separated and can be time- windowed. For each echo, (rho) can be measured and it depends on the echo number. We demonstrate that the precision on the optical constants is greatly enhanced using the p^th echo, the value of p depending on the material refractive index and absorption. Moreover, as the coefficients of the polynomial function can be easily experimentally evaluated, quantitative information on the sources of noise is deduced.

Citation Download Citation

Lionel Duvillaret, Frederic Garet, and Jean-Louis Coutaz "Noise analysis in THz time-domain spectroscopy and accuracy enhancement of optical constant determination", Proc. SPIE 3617, Terahertz Spectroscopy and Applications, (29 April 1999); https://doi.org/10.1117/12.347129

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