Nonlinear chiroptics for biological microscopy

Chirality, or molecular “handedness”, is a defining feature of biomolecules. However, most light-matter interactions are insensitive to molecular chirality, accessing chiral information only through relatively weak high-order magnetic dipole/electric quadrupole interactions. Fortunately, orientational ordering changes the symmetry of chiroptical processes, producing fully electric dipole-allowed chiral observables in both linear and nonlinear optical microscopy. In this work, chiroptical spectroscopy and microscopy based on these interactions are shown to yield spatially resolved contrast uniquely dependent on aligned but unoriented microstructures.