Attenuation coefficients of selected organic and inorganic solvents in the mid-infrared spectral domain

Abstract

Knowledge of the light attenuation by a material is essential for any photonic device, while liquids are insufficiently quantified, especially in the mid-infrared range. Here, we present a quantitative spectroscopic study reporting concrete attenuation values of the regions of low attenuation of selected organic and inorganic solvents up to 20 µm that is useful for light transport and nonlinear frequency conversion. In addition to prominent liquids, the study presents CBrCl3 as a promising candidate for optofluidics. Our study uncovers the potential of these solvents for waveguiding applications at long wavelengths and highlights the importance of careful liquid selection.

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“…The challenge in measuring liquids with such high transparency lies in finding an appropriate method that allows accurate, spectrally broadband referencing as well as light propagation through meter-long samples. Kedenburg et al (and similar work [44][45][46] ) used cuvettes and long tubes (up to 1 m length) sealed with 1 mm thick silica windows. [43] The transmitted spectrum of the tube was measured using a broadband white-light source (e.g., Yokogawa AQ4305, or NKT SuperK) and a fiber-coupled spectrometer at the output.…”

“…[53][54][55] This research focus has provided a solid database that made these liquids the most important candidates for integrated nonlinear optofluidics today. In contrast, other promising candidates (e.g., C 2 Cl 4 [46] and CBrCl 3 [45] ) were disregarded. In particular, the seminal works by Samoc et al [56] and Kedenburg et al [43] have provided a solid basis for dispersion data that enabled a new generation of dispersion models for a variety of common, optics-friendly liquids.…”

“…Only a few works exist where transmission along centimeters of propagation through low‐loss liquids was measured so that attenuation values in application‐ready units (e.g., dB cm −1 ) could be given. [ 43–45 ] Moreover, most loss studies exclude the domain between 1.7 and 3 $$\umu$$m due to the sensitivity limits of the used spectrometers or spectrophotometers.…”

“…Kedenburg et al. (and similar work [ 44–46 ] ) used cuvettes and long tubes (up to 1 m length) sealed with 1 mm thick silica windows. [ 43 ] The transmitted spectrum of the tube was measured using a broadband white‐light source (e.g., Yokogawa AQ4305, or NKT SuperK) and a fiber‐coupled spectrometer at the output.…”

“…Attenuation spectra in the MIR of a) carbon disulfide, b) tetrachloroethylene,and c) carbon tetrachloride, and d) bromoform. Reproduced with permission [45]. Copyright 2022, Optica Publishing Group.…”