2 research outputs found
Midâinfrared dualâcomb polarimetry of anisotropic samples
Abstract The midâinfrared (midâIR) anisotropic optical response of a material probes vibrational fingerprints and absorption bands sensitive to order, structure, and directionâdependent stimuli. Such anisotropic properties play a fundamental role in catalysis, optoelectronic, photonic, polymer and biomedical research and applications. Infrared dualâcomb polarimetry (IRâDCP) is introduced as a powerful new spectroscopic method for the analysis of complex dielectric functions and anisotropic samples in the midâIR range. IRâDCP enables novel hyperspectral and timeâresolved applications far beyond the technical possibilities of classical Fourierâtransform IR approaches. The method unravels structureâspectra relations at high spectral bandwidth up to 90Â cmâ1 and short integration times of 65Â ÎŒs, with previously unattainable time resolutions for spectral IR polarimetric measurements for potential studies of noncyclic and irreversible processes. The polarimetric capabilities of IRâDCP are demonstrated by investigating an anisotropic inhomogeneous freestanding nanofiber scaffold for neural tissue applications. Polarization sensitive multiâangle dualâcomb transmission amplitude and absolute phase measurements (separately for ssâ, ppâ, psâ, and spâpolarized light) allow the inâdepth probing of the samplesâ orientationâdependent vibrational absorption properties. MidâIR anisotropies can quickly be identified by crossâpolarized IRâDCP polarimetry. Key points A novel dualâcomb laserâbased technique is established for polarizationâdependent midâinfrared spectroscopy. Independent measurements of spectral sâ and pâpolarized transmission amplitudes and phases in the ÎŒs range. Visualization of the anisotropy of nanofiber scaffolds as used for neural tissue applications