Conclusion and outlook
Infrared dual-comb polarimetry was introduced as a new polarimetric
technique for studies of anisotropic samples in the mid-IR spectral
range. IR-DCP enables mid-IR polarimetric measurements of amplitudes and
absolute phases at high spectral resolution
(1.4 cm–1). The method was applied to characterize a
nanofiber scaffold with strong in‑plane anisotropy. Azimuthal images of
parallel- and cross-polarized dual-comb spectra were proven to be
applicable for direct inspection of anisotropic vibrational properties.
Having with a single polarizer configuration access to both amplitudes
and absolute phases offers new imaging prospects for cross-polarized
sample properties.
Furthermore, IR-DCP provides sub-millisecond measurement times of 275 µs
or less (potentially even sub-µs). The accessible integration times are
far below those achievable with conventional FTIR techniques, thus
enabling future applications regarding sub-ms resolved spectral
investigations of irreversible or non-cyclic variations of structural
sample properties. The superior time resolution of IR-DCP compared with
other IR approaches renders the method potentially interesting for many
applications in photonics such as process control in the fabrication of
waveguides and functional metasurfaces. In general, the novel
time-resolved polarimetric possibilities could have a high potential
scientific impact for previously unfeasible in situ andoperando studies of irreversible or noncyclic processes or sample
modifications. Further future applications of IR‑DCP will also become
available in other polarimetric measurement geometries.
In summary the developed IR dual-comb polarimetric method has high
potential for chemical and structural studies, e. g., of anisotropic
samples, protein dynamics, phase transitions, chemical modifications and
reactions, which is relevant for material science, catalysis,
biophysics, photonics, rheology and metrology.
Notes The authors declare no conflicts of interest.
Data availability statement The data that support the findings
of this study are available from the corresponding author upon
reasonable request.