Abstract

To clarify the mechanism of second harmonic generation (SHG) in Ge-doped optical fibers, it is very important to know what leads to formation of permanent X(2) grating. Some of the reports [1-3] considered strong internal de fields to be the main reason for writing such gratings. In other papers [4-6] a lot of attention is paid to formation and orientation of color centers and permanent defects. In this great role can play UV-radiation due to simultaneous generation of the third or fourth harmonics.

© 1991 Optical Society of America