Thickness dependence of optical second harmonic generation in collagen fibrils.
Shi-Wei Chu, Shih-Peng Tai, Ming-Che Chan, Chi-Kuang Sun, I-Ching Hsiao, Chi-Hung Lin, Yung-Chih Chen, Bai-Ling Lin
Optics Express | Published : 2007
Simultaneous backward and forward second harmonic generations from isolated type-I collagen matrix are observed. Optical interference behaviors of these nonlinear optical signals are studied with accurately determined fibril thickness by an atomic force microscope. The nonlinear emission directions are strongly dependent on the coherent interaction within and between collagen fibrils. A linear relationship is obtained to estimate collagen fibril thickness with nanometer precision noninvasively by evaluating the forward/backward second harmonic generation ratio.