Theoretical and experimental studies of second-harmonic generation (SHG) in biological tissues was performed by use of ultrashort laser pulses (<1 ps). A simplified one-dimensional model for the generation and the propagation of frequency-doubled light inside tissue was developed. This model was tested <i>in vitro</i> against measurements of pig and chicken tissue and human tooth. The experimental results indicate that the intensity of SHG varies significantly among tissue types and between test sites in individual tissue. Possibilities of using this nonlinear tissue property in imaging and diagnostics are discussed.
© 1999 Optical Society of America
(140.7090) Lasers and laser optics : Ultrafast lasers
(170.6930) Medical optics and biotechnology : Tissue
(190.4160) Nonlinear optics : Multiharmonic generation
(190.7110) Nonlinear optics : Ultrafast nonlinear optics
Beop-Min Kim, Jürgen Eichler, and Luiz B. Da Silva, "Frequency Doubling of Ultrashort Laser Pulses in Biological Tissues," Appl. Opt. 38, 7145-7150 (1999)