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Quantitative Polarization‐Resolved Second‐Harmonic‐Generation Microscopy of Glycine Microneedles
Author(s) -
Gleeson Matthew,
O'Dwyer Kevin,
Guerin Sarah,
Rice Daragh,
Thompson Damien,
Tofail Syed A. M.,
Silien Christophe,
Liu Ning
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202002873
Subject(s) - second harmonic generation , materials science , birefringence , second harmonic imaging microscopy , microscopy , polarization (electrochemistry) , characterization (materials science) , nonlinear optics , optics , nonlinear system , sum frequency generation , nanotechnology , optoelectronics , chemistry , laser , physics , quantum mechanics
Second‐harmonic generation (SHG) is a nonlinear optical process that can provide disease diagnosis through characterization of biological building blocks such as amino acids, peptides, and proteins. The second‐order nonlinear susceptibility tensor χ (2) of a material characterizes its tendency to cause SHG. Here, a method for finding the χ (2) elements from polarization‐resolved SHG microscopy in transmission mode is presented. The quantitative framework and analytical approach that corrects for micrometer‐scale morphology and birefringence enable the determination and comparison of the SHG susceptibility tensors of β‐ and γ‐phase glycine microneedles. The maximum nonlinear susceptibility coefficients are d 33 = 15 pm V −1 for the β and d 33 = 5.9 pm V −1 for the γ phase. The results demonstrate glycine as a useful biocompatible nonlinear material. This combination of the analytical model and polarization‐resolved SHG transmission microscopy is broadly applicable for quantitative SHG material characterization and diagnostic imaging.