We present a practical method to determine femtosecond laser induced refractive index changes in transparent materials. Based on an iterative Fourier transform algorithm, this technique spatially resolves the refractive index of complex structures by combining the dimensions of the modified region with the corresponding phase change extracted from far-field intensity measurements. This approach is used to characterize optical waveguides written by a femtosecond laser in borosilicate glass.
© 2012 Optical Society of America
Lasers and Laser Optics
Original Manuscript: March 30, 2012
Revised Manuscript: June 1, 2012
Manuscript Accepted: June 1, 2012
Published: July 13, 2012
René Berlich, Jiyeon Choi, Clarisse Mazuir, Winston V. Schoenfeld, Stefan Nolte, and Martin Richardson, "Spatially resolved measurement of femtosecond laser induced refractive index changes in transparent materials," Opt. Lett. 37, 3003-3005 (2012)