Electrically Poled, MNA-Microstructured Optical Fibers for Second Harmonic Generation

A hybrid, microstructured optical fiber (MOF) comprised of a silica glass, endlessly single mode optical fiber infiltrated with 2-methyl, 4-nitroaniline (MNA) is subjected to electric field poling for enhancing non-linear wavelength conversion properties. Different poling conditions (temperature, and electric field) are applied, resulting in significant changes manifested in the transmittance and second harmonic generation (SHG) behavior of this hybrid optical fiber. The origins of material and guidance changes induced by the electric poling are investigated by scanning electron microscopy, backscattered SHG microscopy and modal imaging as a function of the polarization state of a 1064 nm, pulsed laser pump. Results show that the improved crystallinity, induced by the poling of the MNA material infiltrated into the MOF capillaries surrounding the optical fiber core, play a dominant role in both SHG efficiency and the transmission performance of these hybrid optical fibers, opening new prospects in the development of in-fiber light switching and wavelength conversion devices.