Polarization-resolved four-wave mixing microscopy for structural imaging in thick tissues

Abstract

We present a polarimetric analysis of the four-wave mixing (FWM) signal emitted by thick tissues, in order to extract structural information on molecular order and orientation. A careful analysis of the polarization distortions introduced by the birefringence of the sample is conducted for the proper interpretation of the results. FWM, compared to other well-known nonlinear optical methods such as second-harmonic generation, gives access to additional information on the symmetry of the molecular distribution. Furthermore, it brings the advantage of being generated in any kind of sample, even when centrosymmetry is present. The model developed here is applied to thick rat-tail tendon samples, composed essentially of collagen fibers. We show that, once the birefringence of the sample is completely characterized, it is possible to retrieve the even-order components of the molecular orientational distribution up to the fourth order of symmetry.

Structure of molecular packing probed by polarization-resolved nonlinear four-wave mixing and coherent anti-Stokes Raman-scattering microscopy

“…[9,10]. Briefly, the pump and Stokes excitation beams come from two synchronized optical parametric oscillators (5 ps, 80 MHz) with a fixed λ p = 735-nm pump wavelength and a Stokes wavelength set at λ s = 884 nm (FWM nonresonant conditions, 2303 cm −1 ), 869 nm (CARS, CD 2 stretching band in the MLV, 2100 cm −1 ), or 929 nm (CARS, CH 2 -stretching band in myelin, 2845 cm −1 ).…”

“…Whereas, polarization-sensitive second-harmonic generation microscopy is restricted to the analysis of noncentrosymmetric assemblies, such as collagen [4][5][6][7] and third-harmonic generation (THG) microscopy is specific to interfaces [8], polarization-resolved four-wave mixing (FWM) microscopy [9] and coherent anti-Stokes Raman-scattering (CARS) microscopy [10,11] potentially are applicable to any kind of molecular assemblies' geometry. Another remarkable property of these contrasts is their high order of nonlinear interaction, making them sensitive to molecular angular distribution features up to the fourth order of symmetry [9,10,12].…”

“…Another remarkable property of these contrasts is their high order of nonlinear interaction, making them sensitive to molecular angular distribution features up to the fourth order of symmetry [9,10,12]. This level of detail, which is a unique way to approach complex molecular organizations, so far, however, has not been used as functional information in bioimaging.…”

Connection of Jones and Mueller Tensors in Second Harmonic Generation and Multi-Photon Fluorescence Measurements

“…Brasselet and co-workers have extensively considered the influence of depolarization and birefringence in nonlinear optical imaging, 43,44 and more recently nicely demonstrated the use of four-wave mixing as a polarization-dependent guide-star signal for characterizing birefringence and depolarization effects in nonlinear optical imaging of biological tissues, although not based on the Mueller formalism. 43,45 Stokes ellipsometry 46–49 and Stokes polarimetry 50 have both been developed for polarization analysis in SHG measurements but not explicitly incorporating a Mueller tensor formalism. By integrating >MHz polarization modulation, Dow et al, have demonstrated full nonlinear optical Stokes ellipsometric microscopy at each pixel in a 512 × 512 image at video rate, 51 potentially enabling in vivo analysis.…”

Contrast in coherent Raman scattering microscopy

“…Nearly a decade and a half after the first collinear CARS microscopy a tremendous number of additional techniques have been introduced. The effects of adjusting every property of the input fields have been well studied: a small sample includes polarization [30][31][32][33][34][35][36][37]; temporal overlap [38][39][40][41][42]; focusing geometry [10,[43][44][45]; phase modulation [13,[46][47][48]; spectral phase [49][50][51][52]; and frequency modulation [53,54].…”